Refereed publications

@inproceedings{HT106,
   title = {Goal-based design improves interaction dependability},
   author = {Harold Thimbleby and Abigail Cauchi and Andy Gimblett and Paul Cairns and Anna Cox},
   year = {in press},
   booktitle = {Digital Engagement 2011},
   location = {Newcastle}
}

@article{jen-iwc,
   title = {The {Digital Reading Desk}: A Lightweight Approach to Digital Note-taking},
   author = {Harold Thimbleby and {\main{Jennifer Pearson}} and George Buchanan},
   year = {in press},
   journal = {Interacting with Computers}
}

@inproceedings{HT36,
   title = {Co-Reading: Investigating Collaborative Group Reading},
   author = {Harold Thimbleby and {\main{J. Pearson}} and George Buchanan},
   year = {in press},
   booktitle = {12th {ACM+IEEE} Joint Conference on Digital Libraries, {JCDL}}
}

@inproceedings{HT37,
   title = {Simulation to evaluate alternative approaches to blocking use errors},
   author = {Harold Thimbleby and Abigail Cauchi and Andy Gimblett},
   year = {2012},
   booktitle = {Proceedings Design of Medical Devices Conference}
}

Quantitative analysis of data log files from infusion pumps used in a large acute NHS hospital.

@inproceedings{HT105,
   title = {Are Prescribed Infusions Running as Intended?},
   author = {Harold Thimbleby and Paul Lee and Carlo {Monroy Aceves} and Patrick Oladimeji},
   abstract = {Quantitative analysis of data log files from infusion pumps used in a large acute NHS hospital.},
   year = {2012},
   booktitle = {Third National Infusion and Vascular Access Society Conference},
   location = {London}
}

@article{HT1,
   title = {Analysis of Infusion Pump Error Logs and Their Significance for Healthcare},
   author = {Harold Thimbleby and Paul Lee and Frankie Thompson},
   year = {2012},
   pages = {S12-ÐS22},
   journal = {British Journal of Nursing},
   volume = {21},
   number = {8}
}

Software should be correct and robust. This paper suggests that we need forthright words for the failure of not being robust — heedless and heedlessness — and of recursively creating software (such as a compiler or virtual machine) that itself does not support dependable software development. Heedless programming is common, particularly affecting “trivial” operations such as on numbers, and extends deep into programming language design and into the use of computers more widely, thus making robust, dependable applications of all sorts unnecessarily problematic. The paper defines the problem and presents a call to action to start addressing the problems identified.

@article{heedless-spae,
   title = {Heedless Programming: Ignoring Detectable Error is a Widespread Hazard},
   author = {Harold Thimbleby},
   abstract = {Software should be correct and robust. This paper suggests that we need forthright words for the failure of not being robust --- \emph{heedless\/} and \emph{heedlessness} --- and of recursively creating software (such as a compiler or virtual machine) that itself does not support dependable software development. Heedless programming is common, particularly affecting ``trivial'' operations such as on numbers, and extends deep into programming language design and into the use of computers more widely, thus making robust, dependable applications of all sorts unnecessarily problematic. The paper defines the problem and presents a call to action to start addressing the problems identified.},
   year = {2012},
   journal = {Software --- Practice {\&} Experience},
   doi = {10.1002/spe.1141}
}

Number entry is an ubiquitous task in medical devices, but is implemented in many different ways, from decimal keypads to seemingly simple up/down buttons. Operator manuals often do not give clear and complete explanations, and all approaches have subtle variations, with details varying from device to device. This paper explores the design issues, critiques designs, and shows that methods have advantages and disadvantages, particularly in terms of undetected error rates.

@inproceedings{HT41,
   title = {Towards Dependable Number Entry for Medical Devices},
   author = {Harold Thimbleby and Abigail Cauchi and Paul Curzon and Parisa Eslambolchilar and Andy Gimblett and Huayi Huang and Paul Lee and Yunqiu Li and Paolo Masci and Patrick Oladimeji and Rimvydas {Ruk\v{s}\.{e}nas}},
   abstract = {Number entry is an ubiquitous task in medical devices, but is implemented in many different ways, from decimal keypads to seemingly simple up/down buttons. Operator manuals often do not give clear and complete explanations, and all approaches have subtle variations, with details varying from device to device. This paper explores the design issues, critiques designs, and shows that methods have advantages and disadvantages, particularly in terms of undetected error rates.},
   year = {2011},
   booktitle = {Proceedings {ACM SIGCHI} Symposium on Engineering Interactive Computing Systems ({EICS}): Engineering Interactive Computing Systems for Medicine and Health Care},
   pages = {53--58},
   publisher = {ACM},
   location = {Pisa, Italy}
}

This workshop brings together and develops the community of researchers and practitioners concerned with the design and evaluation of interactive medical devices (infusion pumps, etc) and systems (electronic patient records, etc), to deliver a roadmap for future research in this area. The workshop involves researchers and practitioners designing and evaluating dependable systems in a variety of contexts, and those developing innovative interactive computer systems for healthcare. These pose particular challenges because of the inherent variability — of patients, system configurations, and so on. Participants will represent a range of perspectives, including safety engineering and innovative design.

@inproceedings{HT40,
   title = {Engineering Interactive Computer Systems for Medicine and Healthcare, {EICS4Med}},
   author = {Harold Thimbleby and Ann Blandford and Giuseppe De Pietro and Luigi Gallo and Andy Gimblett and Patrick Oladimeji},
   abstract = {This workshop brings together and develops the community of researchers and practitioners concerned with the design and evaluation of interactive medical devices (infusion pumps, etc) and systems (electronic patient records, etc), to deliver a roadmap for future research in this area. The workshop involves researchers and practitioners designing and evaluating dependable systems in a variety of contexts, and those developing innovative interactive computer systems for healthcare. These pose particular challenges because of the inherent variability --- of patients, system configurations, and so on. Participants will represent a range of perspectives, including safety engineering and innovative design.},
   year = {2011},
   booktitle = {Proceedings {ACM SIGCHI} Symposium on Engineering Interactive Computing Systems --- {EICS2011}},
   pages = {341--342},
   publisher = {ACM},
   location = {Pisa, Italy}
}

We report on a case study investigating current practice in the use of a programmable infusion pump. We start by formalising an existing description of the procedure followed by nurses for setting up a commercial infusion pump obtained via observation and interview. We then compare and contrast this procedure with a formal description of the sequence of actions reported in the pump’s user manual. Mismatches were validated by a training manager. The aim of this comparison is to point out how minor mismatches between the two descriptions can be used to reveal major safety issues. Our contributions are: first, we analyse a real-world system and show the importance of having a clear and consistent specification of the procedures; second, we show how a graph-based notation can be conveniently used as the basis for building non-ambiguous and intuitive specifications in higher-order logic. We argue that this can provide support to an investigator when building a description of actual practice in that it can help focus attention on areas to observe more closely and on questions to ask to understand why procedures, as followed, are the way they are.

@inproceedings{HT42,
   title = {Comparing Actual Practice and User Manuals: A Case Study Based on Programmable Infusion Pumps},
   author = {Harold Thimbleby and Ann Blandford and Abigail Cauchi and Paul Curzon and Parisa Eslambolchilar and Dominic Furniss and Andy Gimblett and Huayi Huang and Paul Lee and Yunqiu Li and {\main{Paolo Masci}} and Patrick Oladimeji and Atish Rjakomar and Rimvydas {Ruk\v{s}\.{e}nas}},
   abstract = {We report on a case study investigating current practice in the use of a programmable infusion pump. We start by formalising an existing description of the procedure followed by nurses for setting up a commercial infusion pump obtained via observation and interview. We then compare and contrast this procedure with a formal description of the sequence of actions reported in the pump's user manual. Mismatches were validated by a training manager. The aim of this comparison is to point out how minor mismatches between the two descriptions can be used to reveal major safety issues. Our contributions are: first, we analyse a real-world system and show the importance of having a clear and consistent specification of the procedures; second, we show how a graph-based notation can be conveniently used as the basis for building non-ambiguous and intuitive specifications in higher-order logic. We argue that this can provide support to an investigator when building a description of actual practice in that it can help focus attention on areas to observe more closely and on questions to ask to understand why procedures, as followed, are the way they are.},
   year = {2011},
   booktitle = {Proceedings {ACM SIGCHI} Symposium on Engineering Interactive Computing Systems ({EICS}): Engineering Interactive Computing Systems for Medicine and Health Care},
   pages = {59--64},
   publisher = {ACM},
   location = {Pisa, Italy}
}

Reading is increasingly being performed interactively on-screen; for instance, new novels are now routinely released in electronic format for viewing on PCs and mobile devices. Unfortunately, on-screen reading loses many of the natural features of conventional physical media, such as the ability to annotate, slip in bookmarks, turn page corners, and so on. How best should these features be represented electronically? Can computerized representations give benefits that excel the conventional benefits of paper? We describe the design and implementation of a novel reading system that mimics key properties of paper and surpasses them by incorporating digital techniques. A comparative user study evaluating the system confirmed the effectiveness of the features and the value of the system as a whole.

@inproceedings{book-chi,
   title = {The Reading Desk: Applying Physical Interactions to Digital Documents},
   author = {Harold Thimbleby and {\main{Jennifer Pearson}} and George Buchanan},
   abstract = {Reading is increasingly being performed interactively on-screen; for instance, new novels are now routinely released in electronic format for viewing on PCs and mobile devices. Unfortunately, on-screen reading loses many of the natural features of conventional physical media, such as the ability to annotate, slip in bookmarks, turn page corners, and so on. How best should these features be represented electronically? Can computerized representations give benefits that excel the conventional benefits of paper? We describe the design and implementation of a novel reading system that mimics key properties of paper and surpasses them by incorporating digital techniques. A comparative user study evaluating the system confirmed the effectiveness of the features and the value of the system as a whole.},
   year = {2011},
   booktitle = {Proceedings ACM Conference on Computer-Human Interaction --- CHI'2011},
   pages = {3199--3202},
   publisher = {ACM},
   location = {Vancouver, BC, Canada}
}

Seven segment number displays are ubiquitous and popular. They make economic sense: they are simple, and with only seven on/off segments, they require very little wiring and electronics to support. They are cheap to buy and cheap to use; they make cheap and seemingly effective products.

We show how seven segment may be more or less dependable, and suggest some improvements to standard designs. However, we argue that for dependable domains (healthcare, avionics, etc) and for handheld devices that may be used in dependable domains, seven segment displays should not be used.

The paper includes many recommendations for developers and purchasers.

@inproceedings{7-hci,
   title = {don't use 7-segment displays},
   author = {Harold Thimbleby},
   abstract = {Seven segment number displays are ubiquitous and popular. They make economic sense: they are simple, and with only seven on/off segments, they require very little wiring and electronics to support. They are cheap to buy and cheap to use; they make cheap and seemingly effective products. 

We show how seven segment may be more or less dependable, and suggest some improvements to standard designs. However, we argue that for dependable domains (healthcare, avionics, etc) and for handheld devices that may be used in dependable domains, seven segment displays should not be used. 

The paper includes many recommendations for developers and purchasers.},
   year = {2011},
   booktitle = {Proceedings BCS Conference on HCI},
   pages = {3C:1--6},
   publisher = {Oxford University Press},
   location = {Newcastle, England}
}

Health and how to support it with interactive computer systems, networks, and devices is a global and, for many countries, an explicit national priority. Significant interest in issues related to interactive systems for health has been demonstrated repeatedly within SIGCHI. A community focused on health started in 2010, fostering collaboration and dissemination of research findings as well as bridging with practitioners. As part of this community’s on-going efforts, we will hold a special interest group session during ACM CHI 2011 to discuss, prioritize, and promote some of these most pressing issues facing the community.

@inproceedings{health-sig-chi,
   title = {Interactive Technologies for Health Special Interest Group},
   author = {Harold Thimbleby and Helena Mentis and Julie A. Kientz and Gillian R. Hayes and Madhu Reddy},
   abstract = {Health and how to support it with interactive computer systems, networks, and devices is a global and, for many countries, an explicit national priority. Significant interest in issues related to interactive systems for health has been demonstrated repeatedly within SIGCHI{\@}. A community focused on health started in 2010, fostering collaboration and dissemination of research findings as well as bridging with practitioners. As part of this community's on-going efforts, we will hold a special interest group session during {ACM} {CHI} 2011 to discuss, prioritize, and promote some of these most pressing issues facing the community.},
   year = {2011},
   booktitle = {Proceedings ACM Conference on Computer-Human Interaction --- CHI 2011},
   pages = {519--522},
   publisher = {ACM}
}

We define predictability of a user interface as the property that a user can predict with sufficient certainty the effect of any action in a given state in a system, where state information is inferred from the perceptible output of the system. In our definition, the user is not required to have full knowledge of a history of actions from an initial state to the current state. A predicting user relies on cognitive and knowledge assumptions; in this paper we explore the notion in the situation where the user is an expert and understands perfectly how the device works. In this situation predictability concerns whether the user can tell what state the device is in and accurately predict the consequences of an action from that state simply by looking at the device. We give a formal definition of predictability in higher order logic and explore how real systems can be verified against the property. We specify two real number entry interfaces in the medical domain as case studies of predictable and unpredictable user interfaces. We analyse the specifications with respect to our formal definition of predictability and thus show how to make unpredictable systems predictable.

@article{number-fmis,
   title = {The Benefits of Formalising Interactive Number Entry},
   author = {Harold Thimbleby and Andy Gimblett and Rimvydas {Ruk\v{s}\.{e}nas} and Patrick Oladimeji and Abigail Cauchi and Y. Li and P. Curzon and Paolo Masci},
   abstract = {We define \emph{predictability of a user interface\/} as the property that a user can predict with sufficient certainty the effect of any action in a given state in a system, where state information is inferred from the perceptible output of the system. In our definition, the user is not required to have full knowledge of a history of actions from an initial state to the current state. A predicting user relies on cognitive and knowledge assumptions; in this paper we explore the notion in the situation where the user is an expert and understands perfectly how the device works. In this situation predictability concerns whether the user can tell what state the device is in and accurately predict the consequences of an action from that state simply by looking at the device. We give a formal definition of predictability in higher order logic and explore how real systems can be verified against the property. We specify two real number entry interfaces in the medical domain as case studies of predictable and unpredictable user interfaces. We analyse the specifications with respect to our formal definition of predictability and thus show how to make unpredictable systems predictable.},
   year = {2011},
   booktitle = {{FMIS} 2011, 4th International Workshop on Formal Methods for Interactive Systems},
   pages = {1/14--14/14},
   journal = {Electronic Communications of the EASST},
   volume = {45},
   issn = {1863-2122},
   location = {Limerick, Ireland}
}

The design of medical devices directly affects the way healthcare practitioners carry out their daily tasks. Users welcome design that takes into account the clinical environment, in which the device is operated and is compatible with their workflow. However, if the design fails to fit, the likelihood of errors increases, which will put patient safety at risk. In this paper, we report current practice related to UCD (User Centred Design) in the context of medical device, focusing on end user feedback mechanisms deployed in pre-market and post-market phases of the device lifecycle. The results of an interview and workshop study are reported, revealing shortcomings in current feedback channels. In reaction to these shortcomings, we discuss the advantages and feasibility of enabling automatic feedback channel in medical device design, to ensure the quality and the effectiveness of feedback.

@inproceedings{HT38,
   title = {Design of Interactive Medical Devices: Feedback and Its Improvement},
   author = {Harold Thimbleby and {\main{Yunqiu Li}} and Patrick Oladimeji and Carlos Monroy and Abigail Cauchi and Dominic Furniss and Chris Vincent and Ann Blandford},
   abstract = {The design of medical devices directly affects the way healthcare practitioners carry out their daily tasks. Users welcome design that takes into account the clinical environment, in which the device is operated and is compatible with their workflow. However, if the design fails to fit, the likelihood of errors increases, which will put patient safety at risk. In this paper, we report current practice related to UCD (User Centred Design) in the context of medical device, focusing on end user feedback mechanisms deployed in pre-market and post-market phases of the device lifecycle. The results of an interview and workshop study are reported, revealing shortcomings in current feedback channels. In reaction to these shortcomings, we discuss the advantages and feasibility of enabling automatic feedback channel in medical device design, to ensure the quality and the effectiveness of feedback.},
   year = {2011},
   booktitle = {Proceedings IEEE International Symposium on IT in Medicine {\&} Education --- ITME 2011},
   pages = {204--208},
   location = {China}
}

@inproceedings{numbers-interact,
   title = {Number Entry Interfaces and their Effects on Errors and Number Perception},
   author = {Harold Thimbleby and {\main{Patrick Oladimeji}} and Anna Cox},
   year = {2011},
   booktitle = {Proceedings IFIP Conference on Human-Computer Interaction --- Interact 2011},
   pages = {178--185},
   isbn = {978-3-642-23767-6},
   volume = {IV},
   location = {Lisbon, Portugal},
   publisher = {Springer-Verlag}
}

Keyed data entry is fundamental and ubiquitous, occurring when filling data fields in web forms, entering burglar alarm pass-codes, using calculators, entering drug delivery rates in infusion pumps, making cash withdrawals from cash machines, setting destinations for GPS navigation, to name but a few of its applications. Unfortunately data entry is often implemented poorly.

We introduce divergence, a loss of predictability in a user interface, and show that it is in general unavoidable in data entry, and therefore a systematic approach is called for. This paper presents one such an approach. Many inter-related ideas “fall into place”—e.g., autocompletion, prompting, automatic color coding—through the approach. The approach contrasts with conventional systems that are generally inconsistent and unhelpful to users, particularly after errors.

@article{regex-fmis,
   title = {Dependable Keyed Data Entry for Interactive Systems},
   author = {Harold Thimbleby and Andy Gimblett},
   abstract = {Keyed data entry is fundamental and ubiquitous, occurring when filling data fields in web forms, entering burglar alarm pass-codes, using calculators, entering drug delivery rates in infusion pumps, making cash withdrawals from cash machines, setting destinations for GPS navigation, to name but a few of its applications. Unfortunately data entry is often implemented poorly.

We introduce {\emph{divergence}}, a loss of predictability in a user interface, and show that it is in general unavoidable in data entry, and therefore a systematic approach is called for. This paper presents one such an approach. Many inter-related ideas ``fall into place''---e.g., autocompletion, prompting, automatic color coding---through the approach. The approach contrasts with conventional systems that are generally inconsistent and unhelpful to users, particularly after errors.},
   year = {2011},
   booktitle = {{FMIS} 2011, 4th International Workshop on Formal Methods for Interactive Systems},
   pages = {1/16--16/16},
   journal = {Electronic Communications of the EASST},
   url = {http://cs.swan.ac.uk/~csharold/regex},
   volume = {45},
   issn = {1863-2122},
   doi = {10.1145/1996461.1996497},
   location = {Limerick, Ireland}
}

We introduce an architectural software formalism, buffer automata, for the specification, implementation and analysis of a particular class of discrete interactive systems and devices. The approach defines a layer between the physical user interface and the application (if any) and provides a clear framework for highlighting a number of interaction design issues.

@inproceedings{buffer-eics,
   title = {{Buffer} {Automata}: a {UI} architecture prioritising {HCI} concerns for interactive devices},
   author = {Harold Thimbleby and Andy Gimblett and Abigail Cauchi},
   abstract = {We introduce an architectural software formalism, {\emph{buffer automata}}, for the specification, implementation and analysis of a particular class of discrete interactive systems and devices. The approach defines a layer between the physical user interface and the application (if any) and provides a clear framework for highlighting a number of interaction design issues.},
   year = {2011},
   booktitle = {Proceedings {ACM} Engineering Interactive Computer Systems --- {EICS} 2011},
   pages = {73--78},
   publisher = {ACM},
   location = {Pisa, Italy}
}

@inproceedings{HT107,
   title = {The reading desk: Supporting lightweight note-taking in digital documents},
   author = {Harold Thimbleby and Pearson, Jennifer and Buchanan, George},
   year = {2011},
   booktitle = {Proceedings of the 15th international conference on Theory and practice of digital libraries: Research and advanced technology for digital libraries},
   note = {Pearson2011ReadingDesk},
   pages = {438--441},
   isbn = {978-3-642-24468-1},
   url = {http://dl.acm.org/citation.cfm?id=2042536.2042594},
   series = {TPDL'11},
   location = {Berlin, Germany},
   numpages = {4},
   publisher = {Springer-Verlag},
   address = {Berlin, Heidelberg}
}

Number entry is ubiquitous: it is required in many fields including science, healthcare, education, government, mathematics and finance. People entering numbers are to be expected to make errors, but shockingly few systems make any effort to detect, block or otherwise manage errors. Worse, errors may be ignored but processed in arbitrary ways, with unintended results.

A standard class of error (defined in the paper) is an “out by ten error,” which is easily made by miskeying a decimal point or a zero. In safety-critical domains, such as drug delivery, out by ten errors generally have adverse consequences.

Here we expose the extent of the problem of numeric errors in a very wide range of systems. An analysis of better error management is presented: under reasonable assumptions we show that the probability of out by ten errors can be halved by better user interface design. We provide a demonstration user interface to show that the approach is practical.

@article{numbererrors,
   title = {Reducing Number Entry Errors: Solving a Widespread, Serious Problem},
   author = {Harold Thimbleby and Paul Cairns},
   abstract = {Number entry is ubiquitous: it is required in many fields including science, healthcare, education, government, mathematics and finance. People entering numbers are to be expected to make errors, but shockingly few systems make any effort to detect, block or otherwise manage errors. Worse, errors may be ignored but processed in arbitrary ways, with unintended results.

A standard class of error (defined in the paper) is an ``out by ten error,'' which is easily made by miskeying a decimal point or a zero. In safety-critical domains, such as drug delivery, out by ten errors generally have adverse consequences. 

Here we expose the extent of the problem of numeric errors in a very wide range of systems. An analysis of better error management is presented: under reasonable assumptions we show that the probability of out by ten errors can be halved by better user interface design. We provide a demonstration user interface to show that the approach is practical.},
   year = {2010},
   pages = {1429--1439},
   journal = {Journal Royal Society Interface},
   url = {http://cs.swan.ac.uk/~csharold/interface/},
   volume = {7},
   doi = {10.1098/rsif.2010.0112},
   number = {51}
}

Signposts make complex documents more flexible and easier to read; signposts exist in many forms, but are familiar as cross references and as hypertext links. Signposting systems need to be carefully designed, so that they are reliable, easy to use for readers yet convenient for authors to embed in their writing. There are fundamental problems in achieving good signposting, which this paper explores through cross referencing in the popular medium of LaT_EX, which is often the typesetting system of choice for heavily cross referenced documents.

This paper provides an implementation of cross references for LaT_EX users. Problems with LaT_EX and T_EX arise, and are explored and mostly solved: some problems are due to the designs of these systems, but, crucially, some problems are unavoidable, an inevitable part of signposting in principle, whatever systems are used, even including the web.

@article{signposts,
   title = {Signposting in documents},
   author = {Harold Thimbleby},
   abstract = {Signposts make complex documents more flexible and easier to read; signposts exist in many forms, but are familiar as cross references and as hypertext links. Signposting systems need to be carefully designed, so that they are reliable, easy to use for readers yet convenient for authors to embed in their writing. There are fundamental problems in achieving good signposting, which this paper explores through cross referencing in the popular medium of {\LaTeX}, which is often the typesetting system of choice for heavily cross referenced documents.

This paper provides an implementation of cross references for {\LaTeX} users. Problems with {\LaTeX} and {\TeX} arise, and are explored and mostly solved: some problems are due to the designs of these systems, but, crucially, some problems are unavoidable, an inevitable part of signposting in principle, whatever systems are used, even including the web.},
   year = {2010},
   pages = {1119--1135},
   journal = {Computer Journal},
   volume = {54},
   publisher = {OUP},
   doi = {10.1093/comjnl/bxq061},
   number = {7}
}

Motivation — Designers make decisions that later influence how users work with the systems that they have designed. When errors occur in use, it is tempting to focus on the active errors rather than on the latent design decisions that framed the context of error, and fixing latent conditions can have a more general (and future) impact than addressing particular active failures. Research approach — A constructive computer science approach is used, and results from a simulation reported. Research limitations — Error is a complex multidisciplinary field; this paper makes a new contribution complimentary to human factors engineering. Take away message — This paper shows that latent design decisions cause serious problems (including fatalities) in safety critical applications; the paper proposes UI discovery tools to identify and manage latent errors. UI discovery enables human factors engineers and programmers to work together to help eliminate broad classes of latent design errors.

@article{latent-ijhcs,
   title = {Avoiding Latent Design Conditions Using UI Discovery Tools},
   author = {Harold Thimbleby},
   abstract = {Motivation --- Designers make decisions that later influence how users work with the systems that they have designed. When errors occur in use, it is tempting to focus on the active errors rather than on the latent design decisions that framed the context of error, and fixing latent conditions can have a more general (and future) impact than addressing particular active failures. Research approach --- A constructive computer science approach is used, and results from a simulation reported. Research limitations --- Error is a complex multidisciplinary field; this paper makes a new contribution complimentary to human factors engineering. Take away message --- This paper shows that latent design decisions cause serious problems (including fatalities) in safety critical applications; the paper proposes UI discovery tools to identify and manage latent errors. UI discovery enables human factors engineers and programmers to work together to help eliminate broad classes of latent design errors.},
   year = {2010},
   pages = {1--12},
   journal = {International Journal of Human-Computer Studies},
   volume = {26},
   number = {2},
   doi = {10.1080/10447310903498692}
}

As interactive digital documents are becoming more and more commonplace, we find ourselves searching for new ways to make good use of them. The fast delivery and large storage capacity that digital devices offer, make reading from bulky physical books seem obsolete, even nonsensical. EReaders, the latest craze in digital reading, follows from the introduction of eInk and promises paper-like reading capabilities with the added digital benefits. But is the excitement justified? Can you ‘curl up’ with an eReader in the same way as you can a physical book, or is the design of eReading devices hindering this process?.

As of yet, no one has taken a scientific view of current eReader technology from the systematic standpoint of basic HCI principles. This paper discusses guidelines for good eReader design and illustrates them with examples of shortcomings of some of the more popular eReader devices on the market today.

@inproceedings{HT43,
   title = {{HCI} Design Principles for {eReaders}},
   author = {Harold Thimbleby and {\main{Jennifer Pearson}} and George Buchanan},
   abstract = {As interactive digital documents are becoming more and more commonplace, we find ourselves searching for new ways to make good use of them. The fast delivery and large storage capacity that digital devices offer, make reading from bulky physical books seem obsolete, even nonsensical. EReaders, the latest craze in digital reading, follows from the introduction of eInk and promises paper-like reading capabilities with the added digital benefits. But is the excitement justified? Can you `curl up' with an eReader in the same way as you can a physical book, or is the design of eReading devices hindering this process?.

As of yet, no one has taken a scientific view of current eReader technology from the systematic standpoint of basic HCI principles. This paper discusses guidelines for good eReader design and illustrates them with examples of shortcomings of some of the more popular eReader devices on the market today.},
   year = {2010},
   booktitle = {Proceedings BooksOnline'10: Proceedings of the third workshop on research advances in large digital book repositories and complementary media},
   pages = {15--24},
   isbn = {978-1-4503-0377-4},
   doi = {10.1145/1871854.1871860},
   location = {Toronto, Ontario, Canada}
}

@inproceedings{discovery-eics,
   title = {User Interface Model Discovery: Towards a Generic Approach},
   author = {Harold Thimbleby and Andy Gimblett},
   year = {2010},
   booktitle = {Proceedings ACM SIGCHI Symposium on Engineering Interactive Computing Systems --- EICS 2010},
   pages = {145--154},
   highlight = {Best Paper Award},
   editor = {G. Doherty and J. Nichols and Michael D. Harrison},
   location = {Berlin},
   doi = {10.1145/1822018.1822041},
   publisher = {ACM}
}

There is evidence that widely used interactive medical devices such as infusion pumps pose interaction difficulties. Yet this evidence is widely dispersed, and difficulties in programming, interaction and socio-technical design have rarely been a focus for study. Interaction difficulties are effectively invisible. To understand why, it is necessary to study the cultural and organizational contexts within which devices are designed, deployed and used. In this paper, we present examples illustrating interaction difficulties and outline features of the context that keep those difficulties invisible.

@inproceedings{few-chi,
   title = {Few are Looking: Invisible Problems with Interactive Medical Devices},
   author = {Harold Thimbleby and Ann Blandford and George Buchanan and Dominic Furniss and P. Curzon},
   abstract = {There is evidence that widely used interactive medical devices such as infusion pumps pose interaction difficulties. Yet this evidence is widely dispersed, and difficulties in programming, interaction and socio-technical design have rarely been a focus for study. Interaction difficulties are effectively invisible. To understand why, it is necessary to study the cultural and organizational contexts within which devices are designed, deployed and used. In this paper, we present examples illustrating interaction difficulties and outline features of the context that keep those difficulties invisible.},
   year = {2010},
   booktitle = {Proceedings of the ACM Workshop on Interactive Systems in Healthcare ({WISH}) --- {CHI} 2010},
   pages = {9-12},
   location = {Atlanta},
   publisher = {ACM},
   editor = {G. R. Hayes and D. S. Tan}
}

To achieve dependable, usable, and well-engineered interactive devices in healthcare requires applied Human Computer Interaction (HCI) research and awareness of HCI issues throughout the lifecycle, from design through to procurement, training and use. This paper shows that some healthcare devices fall far short, and thus identifies a gap in applied HCI.

We use a basic, interactive hospital bed as a case study, arguably so routine and simple enough that there should have been very few problems. However, the bed’s interactive control panel design violates standard HCI principles. It is also badly programmed by the manufacturer. Evidently, something has gone wrong, somewhere from design to procurement, and we argue most of the problems would have been managed or avoided by conventional HCI processes.

Driven by the case study, this paper explores the problems and makes recommendations. There are many similarly poorly designed medical devices. Manufacturers and healthcare purchasing groups should adhere to HCI processes and guidelines, as well as those provided by regulatory agencies for the design, regulation, and procurement of devices, products, or systems that contribute to patient safety. The challenge is to make HCI knowledge and priorities available to and effective in this important domain in any places that can make a difference.

@inproceedings{chitra-bcs,
   title = {Human Computer Interaction and Medical Devices},
   author = {Harold Thimbleby and {\main{Chitra Acharya}} and Patrick Oladimeji},
   abstract = {To achieve dependable, usable, and well-engineered interactive devices in healthcare requires applied Human Computer Interaction (HCI) research and awareness of HCI issues throughout the lifecycle, from design through to procurement, training and use. This paper shows that some healthcare devices fall far short, and thus identifies a gap in applied HCI.

We use a basic, interactive hospital bed as a case study, arguably so routine and simple enough that there should have been very few problems. However, the bed's interactive control panel design violates standard HCI principles. It is also badly programmed by the manufacturer. Evidently, something has gone wrong, somewhere from design to procurement, and we argue most of the problems would have been managed or avoided by conventional HCI processes.

Driven by the case study, this paper explores the problems and makes recommendations. There are many similarly poorly designed medical devices. Manufacturers and healthcare purchasing groups should adhere to HCI processes and guidelines, as well as those provided by regulatory agencies for the design, regulation, and procurement of devices, products, or systems that contribute to patient safety. The challenge is to make HCI knowledge and priorities available to and effective in this important domain in any places that can make a difference.},
   year = {2010},
   booktitle = {Proceedings BCS Conference on {HCI}},
   location = {Dundee},
   publisher = {BCS}
}

This paper uses a simple analogy. A gun is designed to shoot bullets, but it is obvious that accidentally shooting is a danger one should avoid if at all possible. Thus guns have safety locks, which aim to protect users and bystanders.

Interactive computer systems sometimes accidentally do bad things too, but something like “safety locks” are not often enough implemented to help protect user or bystanders from harm.

Worse, user interfaces often behave quite unpredictably with erroneous input Ñ– rather than blocking errors and requiring the user to correct them. This is a bit like guns that misbehave.

Computers and computers embedded in everyday devices are not always as dangerous as guns, although there are many cases where they can be as dangerous. Medical devices may give patients undetected overdoses. In-car entertainment devices, like radios, may, through their badly-designed user interfaces, cause a driver to have an accident. A slip in a spreadsheet may be the first step towards an organisation going bankrupt. And so on.

The solution should include better design, including the concept of safety locks, that block some forms of user error.

@article{think!,
   title = {Think! Interactive Systems Need Safety Locks},
   author = {Harold Thimbleby},
   abstract = {This paper uses a simple analogy. A gun is designed to shoot bullets, but it is obvious that accidentally shooting is a danger one should avoid if at all possible. Thus guns have safety locks, which aim to protect users and bystanders.

Interactive computer systems sometimes accidentally do bad things too, but something like ``safety locks'' are not often enough implemented to help protect user or bystanders from harm.

Worse, user interfaces often behave quite unpredictably with erroneous input Ñ-- rather than blocking errors and requiring the user to correct them. This is a bit like guns that misbehave.

Computers and computers embedded in everyday devices are not always as dangerous as guns, although there are many cases where they can be as dangerous. Medical devices may give patients undetected overdoses. In-car entertainment devices, like radios, may, through their badly-designed user interfaces, cause a driver to have an accident. A slip in a spreadsheet may be the first step towards an organisation going bankrupt. And so on.

The solution should include better design, including the concept of {\textbf{safety}} locks, that block some forms of user error.},
   year = {2010},
   pages = {349--360},
   journal = {Journal of Computing and Information Technology},
   volume = {18},
   number = {4},
   doi = {10.2498/cit.1001921}
}

User interfaces often behave unpredictably on erroneous input — rather than blocking errors and requiring the user to correct them. The consequences of this in the context of medical devices, which may give patients undetected overdoses, can be unfortunate. The solution should include better design, including the concept of safety locks, that block some forms of user error.

@inproceedings{think-cavtat,
   title = {Interactive systems need safety locks},
   author = {Harold Thimbleby},
   abstract = {User interfaces often behave unpredictably on erroneous input --- rather than blocking errors and requiring the user to correct them. The consequences of this in the context of medical devices, which may give patients undetected overdoses, can be unfortunate. The solution should include better design, including the concept of safety locks, that block some forms of user error.},
   year = {2010},
   booktitle = {Proceedings of the IEEE ITI 2010 32nd International Conference on Information Technology Interfaces},
   aftertitle = {Keynote},
   pages = {29--36},
   isbn = {978--953--7138--18-9},
   editor = {V. Luzar-Stiffler and I. Jarec and Z. Bekic},
   location = {Cavtat, Croatia}
}

@inproceedings{HT108,
   title = {Improving Annotations In Digital Documents},
   author = {Harold Thimbleby and {\main{Jennifer Pearson}} and George Buchanan},
   year = {2009},
   booktitle = {Proceedings of the 13th European conference on Research and advanced technology for digital libraries --- ECDL'09},
   pages = {429--432},
   isbn = {978-3-642-04345-1},
   volume = {5714},
   editor = {M. Agosti and J. Borbinha and S. Kapidakis and C. Papatheodorou and G. Tsakonas},
   series = {Lecture Notes in Computer Science},
   publisher = {Springer Verlag},
   location = {Corfu, Greece}
}

What methods can we use to help understand why users adopt certain use strategies, and how can we evaluate designs to anticipate and perhaps positively modify how users are likely to behave? This paper proposes taking advantage of social network analysis (SNA) to identify features of interaction. There are plausible reasons why SNA should be relevant to interaction programming and design, but we also show that SNA has promise, identifies and explains interesting use phenomena, and can be used effectively on conventionally-programmed interactive devices. Social network analysis is a very rich field, practically and theoretically, and many further forms of application and analysis beyond the promising examples explored in this paper are possible.

@inproceedings{network-eics,
   title = {Social Network Analysis and Interactive Device Design},
   author = {Harold Thimbleby and Patrick Oladimeji},
   abstract = {What methods can we use to help understand why users adopt certain use strategies, and how can we evaluate designs to anticipate and perhaps positively modify how users are likely to behave? This paper proposes taking advantage of social network analysis (SNA) to identify features of interaction. There are plausible reasons why SNA should be relevant to interaction programming and design, but we also show that SNA has promise, identifies and explains interesting use phenomena, and can be used effectively on conventionally-programmed interactive devices. Social network analysis is a very rich field, practically and theoretically, and many further forms of application and analysis beyond the promising examples explored in this paper are possible.},
   year = {2009},
   booktitle = {Proceedings {ACM} {SIGCHI} Symposium on Engineering Interactive Computing Systems --- {EICS}'09},
   pages = {91--100},
   editor = {G. Calvary and T. C. N. Graham and P. Gray},
   location = {Pittsburgh},
   publisher = {ACM},
   doi = {10.1145/1570433.1570453}
}

Motivation — Designers make decisions that later influence how users work with the systems that they have designed. When errors occur in use, it is tempting to focus on the active errors rather than on the latent design decisions that framed the context of error, and fixing latent conditions can have a more general (and future) impact than addressing particular active failures. Research approach — A constructive computer science approach is used, and results from a simulation reported. Research limitations — Error is a complex multidisciplinary field; this paper makes a new contribution complimentary to human factors engineering. Take away message — This paper shows that latent design decisions cause serious problems (including fatalities) in safety critical applications; the paper proposes UI discovery tools to identify and manage latent errors. UI discovery enables human factors engineers and programmers to work together to help eliminate broad classes of latent design errors.

@inproceedings{ndm-keynote,
   title = {Avoiding latent design conditions using UI discovery tools},
   author = {Harold Thimbleby},
   abstract = {{\textbf{Motivation}} --- Designers make decisions that later influence how users work with the systems that they have designed. When errors occur in use, it is tempting to focus on the active errors rather than on the latent design decisions that framed the context of error, and fixing latent conditions can have a more general (and future) impact than addressing particular active failures. {\textbf{Research approach}} --- A constructive computer science approach is used, and results from a simulation reported. {\textbf{Research limitations}} --- Error is a complex multidisciplinary field; this paper makes a new contribution complimentary to human factors engineering. {\textbf{Take away message}} --- This paper shows that latent design decisions cause serious problems (including fatalities) in safety critical applications; the paper proposes UI discovery tools to identify and manage latent errors. UI discovery enables human factors engineers and programmers to work together to help eliminate broad classes of latent design errors.},
   year = {2009},
   booktitle = {Proceedings 9th Naturalistic Decision Making, NDM9},
   aftertitle = {Keynote},
   pages = {20--27},
   editor = {B. L. W. Wong and N. A. Stanton},
   location = {London},
   doi = {10.1080/10447310903498692}
}

Interaction programming bridges the gap between interaction design and programming, but it has not yet been related directly to mainstream development practice. This paper presents UI model discovery tools to enable existing systems and traditional development processes to benefit from interaction programming tools and methods.

@inproceedings{interaction-chi,
   title = {Interaction Programming: Next Steps},
   author = {Harold Thimbleby},
   abstract = {Interaction programming bridges the gap between interaction design and programming, but it has not yet been related directly to mainstream development practice. This paper presents UI model discovery tools to enable existing systems and traditional development processes to benefit from interaction programming tools and methods.},
   year = {2009},
   booktitle = {Proceedings {ACM} {CHI}},
   pages = {3811--3816},
   doi = {10.1145/1520340.1520576},
   publisher = {ACM}
}

Interaction programming bridges the gap between interaction design and programming, but it has not yet been related directly to mainstream user interface development practice. This paper presents UI model discovery tools to enable existing systems and traditional development processes to benefit from interaction programming tools and methods; in particular, to enable checking of safety-critical interaction properties, and to contribute to due diligence practices in safety-critical interactive systems design.

@inproceedings{safety-eics,
   title = {Contributing to Safety and Due Diligence in Safety-critical Interactive Systems Development},
   author = {Harold Thimbleby},
   abstract = {Interaction programming bridges the gap between interaction design and programming, but it has not yet been related directly to mainstream user interface development practice. This paper presents {\emph{UI model discovery tools\/}} to enable existing systems and traditional development processes to benefit from interaction programming tools and methods; in particular, to enable checking of safety-critical interaction properties, and to contribute to due diligence practices in safety-critical interactive systems design.},
   year = {2009},
   booktitle = {Proceedings {ACM} {SIGCHI} Symposium on Engineering Interactive Computing Systems --- {EICS}'09},
   pages = {221--230},
   editor = {G. Calvary and T. C. N. Graham and P. Gray},
   location = {Pittsburgh},
   publisher = {ACM},
   doi = {10.1145/1570433.1570474}
}

We consider how to teach effectively with particular reference to HCI. HCI can be taught to explicitly empower students to engage with their own learning. Further, HCI motivates because HCI empowers students to make a valuable and lasting contribution to the world.

@inproceedings{learn-hcii,
   title = {Teaching and Learning {HCI}},
   author = {Harold Thimbleby},
   abstract = {We consider how to teach effectively with particular reference to HCI\@. HCI can be taught to explicitly empower students to engage with their own learning. Further, HCI motivates because HCI empowers students to make a valuable and lasting contribution to the world.},
   year = {2009},
   booktitle = {Proceedings {HCI} International, Part I, Universal Access, {HCII} 2009},
   pages = {625--635},
   volume = {5614},
   publisher = {Springer Verlag},
   series = {Lecture Notes in Computer Science},
   location = {San Diego},
   editor = {C. Stephanidis},
   doi = {10.1007/978-3-642-02707-9_71}
}

@inbook{HT169,
   title = {Write Now!},
   author = {Harold Thimbleby},
   year = {2008},
   booktitle = {Research Methods for Human-Computer Interaction},
   pages = {196--211},
   editor = {Paul Cairns and Anna Cox},
   publisher = {Cambridge University Press}
}

@article{HT199,
   title = {Ignorance of interaction programming is killing people},
   author = {Harold Thimbleby},
   year = {September+October, 2008},
   pages = {52--57},
   journal = {ACM Interactions},
   url = {http://harold.thimbleby.net/health}
}

@inproceedings{hci3med-bcs,
   title = {Workshop on {HCI} for Medicine and Health Care ({HCI4MED})},
   author = {Harold Thimbleby and {\main{Andreas Holzinger}} and Russell Beale},
   year = {2008},
   booktitle = {Proceedings BCS HCI Conference, People and Computers},
   pages = {191--192},
   volume = {XXII.2},
   location = {Liverpool, England},
   publisher = {BCS}
}

Graph theory provides a very substantial resource for a diverse range of quantitative and qualitative usability measures, which may be used for evaluating recovery from error, informing design tradeoffs, probing topics for user training, and so on. This paper gives many concrete examples based on the analysis of a real non-trivial interactive device, a medical syringe pump, itself implemented as a graph.

Graph theory is a straight-forward, practical and flexible way to implement and analyse real interactive systems. Hence, graph theory complements other approaches to formal HCI, such as theorem proving and model checking, which have a less direct relation to interaction.

@inproceedings{graph-dsvis,
   title = {Applying Graph Theory to Interaction Design},
   author = {Harold Thimbleby and Jeremy Gow},
   abstract = {Graph theory provides a very substantial resource for a diverse range of quantitative and qualitative usability measures, which may be used for evaluating recovery from error, informing design tradeoffs, probing topics for user training, and so on. This paper gives many concrete examples based on the analysis of a real non-trivial interactive device, a medical syringe pump, itself implemented as a graph. 

Graph theory is a straight-forward, practical and flexible way to implement and analyse {\emph{real\/}} interactive systems. Hence, graph theory complements other approaches to formal HCI, such as theorem proving and model checking, which have a less direct relation to interaction.},
   year = {2008},
   booktitle = {Proceedings Engineering Interactive Computer Systems --- EICS2007/DSVIS 2007},
   pages = {501--518},
   volume = {4940},
   publisher = {Springer Verlag},
   series = {Lecture Notes in Computer Science},
   editor = {J. Gulliksen},
   location = {Salamanca, Spain},
   doi = {10.1007/978-3-540-92698-6_30}
}

Affordance is a widely-used term in human-computer interaction that, while familiar and attractive, does not have a clear operational definition. Using the mathematical concept of symmetry, this paper shows it is possible to begin developing an operational definition for significant aspects of affordance by forming the theoretical concept of symmetry-affordance. The proposed definition restricts symmetry-affordance to particular contexts but in doing so makes it more useful, as it is clear how to exploit symmetry to aid design. The definition is in standard mathematics (in fact, group theory and model theory) and requires little additional structure. In examining symmetry-affordance, it becomes clear that some other HCI notions can be similarly interpreted by symmetry. The paper provides examples and design insights.

“Symmetry, as wide or as narrow as you may define its meaning, is one idea by which man through the ages has tried to comprehend and create order, beauty, and perfection.” Hermann Weyl

@article{affordance-cj,
   title = {Affordance and Symmetry in User Interfaces},
   author = {Harold Thimbleby and Paul Cairns},
   abstract = {Affordance is a widely-used term in human-computer interaction that, while familiar and attractive, does not have a clear operational definition. Using the mathematical concept of symmetry, this paper shows it is possible to begin developing an operational definition for significant aspects of affordance by forming the theoretical concept of {\emph{symmetry-affordance}}. The proposed definition restricts symmetry-affordance to particular contexts but in doing so makes it more useful, as it is clear how to exploit symmetry to aid design. The definition is in standard mathematics (in fact, group theory and model theory) and requires little additional structure. In examining symmetry-affordance, it becomes clear that some other HCI notions can be similarly interpreted by symmetry. The paper provides examples and design insights.

``Symmetry, as wide or as narrow as you may define its meaning, is one idea by which man through the ages has tried to comprehend and create order, beauty, and perfection.'' {\emph{Hermann~Weyl}}},
   year = {2008},
   pages = {650--661},
   journal = {Computer Journal},
   volume = {51},
   number = {6},
   doi = {10.1093/comjnl/bxm102}
}

Science fiction stories seductively portray robots as human. In present reality (early 21st century) robots are machines, even though they can do many things far better than humans (fly, swim, play chess to name a few). Any ethics for or of robots is therefore a seductive mix of fiction and reality. The key issue for rational discourse is to provide a rigorous framework for reasoning about the issues, including identifying flaws in the framework. We find such meta-reasoning in discussion about robot ethics to be ready for improvement.

@article{robot-iwc,
   title = {Robot ethics? {Not} yet. {A} reflection on {Whitby's} ``{Sometimes} it's hard to be a robot''},
   author = {Harold Thimbleby},
   abstract = {Science fiction stories seductively portray robots as human. In present reality (early 21st century) robots are machines, even though they can do many things far better than humans (fly, swim, play chess to name a few). Any ethics for or of robots is therefore a seductive mix of fiction and reality. The key issue for rational discourse is to provide a rigorous framework for reasoning about the issues, including identifying flaws in the framework. We find such meta-reasoning in discussion about robot ethics to be ready for improvement.},
   year = {2008},
   pages = {338--341},
   journal = {Interacting with Computers},
   volume = {20},
   number = {3},
   doi = {10.1016/j.intcom.2008.02.006}
}

We can consider a calculator together with its user make a Turing Complete system; in this sense, all calculators are mathematically equivalent and therefore mathematical user interfaces need not innovate beyond what is absolutely necessary. Typically, user interfaces are character-based and imperative, with mice used to select windows, and modes used to control the hidden complexities of the system.

Taking Mathematica and xThink as representatives of the state of the art in interactive mathematics, we show conventional mathematical user interfaces leave much to be desired, because they separate the mathematics from the context of the user interface, which remains as unmathematical as ever.

We put the usability of such systems into mathematical perspective, and compare the conventional approach with our approach, as exemplified by True Calculator.

@inproceedings{math-dsvis,
   title = {Mathematical Mathematical User Interfaces},
   author = {Harold Thimbleby and Will Thimbleby},
   abstract = {We can consider a calculator together with its user make a Turing Complete system; in this sense, all calculators are mathematically equivalent and therefore mathematical user interfaces need not innovate beyond what is absolutely necessary. Typically, user interfaces are character-based and imperative, with mice used to select windows, and modes used to control the hidden complexities of the system.

Taking Mathematica and xThink as representatives of the state of the art in interactive mathematics, we show conventional mathematical user interfaces leave much to be desired, because they separate the mathematics from the context of the user interface, which remains as unmathematical as ever. 

We put the usability of such systems into mathematical perspective, and compare the conventional approach with our approach, as exemplified by True Calculator.},
   year = {2008},
   booktitle = {Proceedings Engineering Interactive Computer Systems --- EICS2007/{DSVIS} 2007},
   pages = {519--535},
   url = {http://cs.swan.ac.uk/~csharold/calculators/index.html},
   volume = {4940},
   location = {Salamanca, Spain},
   publisher = {Springer Verlag},
   series = {Lecture Notes in Computer Science},
   editor = {J. Gulliksen},
   doi = {10.1007/978-3-540-92698-6_31}
}

@inproceedings{research-bcs,
   title = {Research Methods for {HCI}},
   author = {Harold Thimbleby and {\main{Anna Cox}} and {\main{Paul Cairns}} and Natalie Webb},
   year = {2008},
   booktitle = {Proceedings BCS HCI Conferences, People and Computers},
   pages = {221--222},
   volume = {XXII.2},
   location = {Liverpool, England},
   publisher = {BCS}
}

Papers in HCI play different roles, whether to inspire, solve industrial problems or further the science of HCI. There is a potential conflict between the different views, and a danger that different forms of validity are assumed by author and reader — deliberately or accidentally.

This paper reviews some of the issues in this complex area and makes practical recommendations. In particular, the paper introduces the term “cross-validity” to help make explicit the issues, problems and means to tackle them.

@inproceedings{validity-dsvis,
   title = {Validity and Cross-Validity in {HCI} publications},
   author = {Harold Thimbleby},
   abstract = {Papers in HCI play different roles, whether to inspire, solve industrial problems or further the science of HCI\@. There is a potential conflict between the different views, and a danger that different forms of validity are assumed by author and reader --- deliberately or accidentally. 

This paper reviews some of the issues in this complex area and makes practical recommendations. In particular, the paper introduces the term ``cross-validity'' to help make explicit the issues, problems and means to tackle them.},
   year = {2007},
   booktitle = {Proceedings The {XIII} International Workshop on Design, Specification and Verification of Interactive Systems --- {DSVIS} 2006},
   pages = {11--24},
   volume = {4323},
   publisher = {Springer Verlag},
   series = {Lecture Notes in Computer Science},
   editor = {G. Doherty and Ann Blandford},
   location = {Dublin, Ireland}
}

This short paper argues that references in user interfaces, in particular names and the values they denote, are often designed in a way that is incomplete and inconsistent thereby causing problems for users. This paper explores names and values through illustrations in order to clear the way for a more systematic approach to the design of names and reference.

@inproceedings{names-bcs,
   title = {Names and References in User Interfaces},
   author = {Harold Thimbleby and Michael D. Harrison},
   abstract = {This short paper argues that references in user interfaces, in particular names and the values they denote, are often designed in a way that is incomplete and inconsistent thereby causing problems for users. This paper explores names and values through illustrations in order to clear the way for a more systematic approach to the design of names and reference.},
   year = {2007},
   booktitle = {Proceedings British Computer Society {HCI} 2007 Conference},
   pages = {107--110},
   volume = {2},
   location = {Lancaster, England}
}

@inproceedings{fitts-fmis,
   title = {Using the Fitts Law with State Transition Systems to Find Optimal Task Timings},
   author = {Harold Thimbleby},
   year = {2007},
   booktitle = {Proceedings 2nd International Workshop on Formal Methods for Interactive Systems ({FMIS2007})},
   pages = {151--162},
   editor = {P. Curzon and A. Cerone},
   location = {Lancaster, England}
}

@inproceedings{utaut-bcs,
   title = {Validating the Unified Theory of Acceptance and Use of Technology ({UTAUT}) tool cross-culturally},
   author = {Harold Thimbleby and {\main{Lidia Oshlyansky}} and Paul Cairns},
   year = {2007},
   booktitle = {Proceedings British Computer Society {HCI} 2007 Conference},
   pages = {83--86},
   volume = {2}
}

The history of technology, as a discipline, supports alternate points of view termed internalist and externalist, which terms highlight an approximately similar division in points of view in HCI. Conventional HCI is externalist, rightly concerned with human-centered issues; but externalism risks ignoring important internalist issues. A successful human-computer system is better if it is successful from both perspectives. This discussion paper argues that the externalist view, while necessary and immensely useful, is not sufficient — and in the worst case, risks eclipsing innovation from internalist quarters.

@inproceedings{internalist-bcs,
   title = {Internalist and Externalist {HCI}},
   author = {Harold Thimbleby and Will Thimbleby},
   abstract = {The history of technology, as a discipline, supports alternate points of view termed internalist and externalist, which terms highlight an approximately similar division in points of view in HCI\@. Conventional HCI is externalist, rightly concerned with human-centered issues; but externalism risks ignoring important internalist issues. A successful human-computer system is better if it is successful from both perspectives. This discussion paper argues that the externalist view, while necessary and immensely useful, is not sufficient --- and in the worst case, risks eclipsing innovation from internalist quarters.},
   year = {2007},
   booktitle = {Proceedings British Computer Society {HCI} 2007 Conference},
   pages = {111--114},
   volume = {2},
   location = {Lancaster, England}
}

Usability evaluation methods are a battery of techniques for assessing the usability of interactive systems or of proposed interactive systems. This paper describes a new evaluation method, particularly appropriate for evaluating safety critical and high quality user interfaces. The method can also be used for informing HCI research. The method is applied when a specification is available of an interactive system, or when a system (or prototype) is working.

@inproceedings{walkthrough-dsvis,
   title = {Interaction Walkthrough: Evaluation of Safety Critical Interactive Systems},
   author = {Harold Thimbleby},
   abstract = {Usability evaluation methods are a battery of techniques for assessing the usability of interactive systems or of proposed interactive systems. This paper describes a new evaluation method, particularly appropriate for evaluating safety critical and high quality user interfaces. The method can also be used for informing HCI research. The method is applied when a specification is available of an interactive system, or when a system (or prototype) is working.},
   year = {2007},
   booktitle = {Proceedings The {XIII} International Workshop on Design, Specification and Verification of Interactive Systems --- {DSVIS} 2006},
   pages = {52--66},
   volume = {4323},
   publisher = {Springer Verlag},
   series = {Lecture Notes in Computer Science},
   editor = {G. Doherty and Ann Blandford},
   location = {Dublin, Ireland},
   doi = {10.1007/978-3-540-69554-7_5}
}

@inproceedings{HT45,
   title = {Automatic Critiques of Interface Modes},
   author = {Harold Thimbleby and {\main{Jeremy Gow}} and Paul Cairns},
   year = {2006},
   booktitle = {Proceedings Interactive Systems, Design, Specification, and Verification 12th. International Workshop --- DSVIS 2005},
   note = {Revised Papers},
   pages = {201--212},
   volume = {3941},
   publisher = {Springer Verlag},
   series = {Lecture Notes in Computer Science},
   editor = {S. W. Gilroy and Michael D. Harrison},
   location = {Newcastle, England},
   issn = {0302--9743}
}

@inproceedings{HT46,
   title = {Applying Bohm's ideas in the age of intelligent environments},
   author = {Harold Thimbleby},
   year = {2006},
   booktitle = {Proceedings International Symposium on Intelligent Environments},
   pages = {27--33},
   location = {Cambridge, England}
}

@inproceedings{hofstede-bcs,
   title = {A Cautionary Tale: Hofstede's {VSM} Revisited},
   author = {Harold Thimbleby and {\main{Lidia Oshlyansky}} and Paul Cairns},
   year = {2006},
   booktitle = {Proceedings of British Computer Society Human Computer Interaction Conference},
   pages = {11--15},
   volume = {2},
   location = {Edinburgh, Scotland}
}

@inproceedings{auto-dsvis,
   title = {Automatic Critiques of Interface Modes},
   author = {Harold Thimbleby and {\main{Jeremy Gow}} and Paul Cairns},
   year = {2005},
   booktitle = {Proceedings 12th International Workshop on Design, Specification and Verification of Interactive Systems --- {DSVIS} 2005},
   pages = {189--200},
   volume = {3941},
   publisher = {Springer Verlag},
   series = {Lecture Notes in Computer Science},
   editor = {S. W. Gilroy and Michael D. Harrison}
}

@inproceedings{lost2-bcs,
   title = {Lost --- or Liberated? --- Without Theory},
   author = {Harold Thimbleby and J. Gulliksen and I. Boivie and L. Bannon and Lidia Oshlyansky},
   year = {2005},
   booktitle = {Proceedings 19th. British Computer Society {HCI} Conference},
   pages = {299--301},
   volume = {2},
   editor = {L. MacKinnon and O. Bertelsen and N. Bryan-Kinns},
   publisher = {British Computer Society},
   location = {Edinburgh, Scotland}
}

@inbook{HT203,
   title = {Weapons of Maths Construction},
   author = {Harold Thimbleby and W.~Thimbleby},
   year = {2005},
   booktitle = {Royal Society Summer Science Exhibition Guide},
   pages = {6--7}
}

@inproceedings{will-bcs,
   title = {A Novel Gesture-Based Calculator and Its Design Principles},
   author = {Harold Thimbleby and {\main{Will Thimbleby}}},
   year = {2005},
   booktitle = {Proceedings 19th. British Computer Society {HCI} Conference},
   pages = {27--32},
   url = {http://cs.swan.ac.uk/~csharold/calculators/index.html},
   volume = {2},
   editor = {L. MacKinnon and O. Bertelsen and N. Bryan-Kinns},
   publisher = {British Computer Society},
   location = {Edinburgh, Scotland}
}

@inproceedings{HT109,
   title = {Weapons of Maths Construction},
   author = {Harold Thimbleby and Will Thimbleby},
   year = {2005},
   booktitle = {Royal Society Summer Science Exhibition},
   url = {http://cs.swan.ac.uk/calculators},
   location = {London \& Mumbai}
}

@inproceedings{lost-bcs,
   title = {Lost --- or Liberated? --- Without Theory},
   author = {Harold Thimbleby and J. Gulliksen and I. Boivie and L. Bannon and Lidia Oshlyansky},
   year = {2005},
   booktitle = {Proceedings 19th. British Computer Society {HCI} Conference},
   pages = {344},
   volume = {2},
   editor = {L. MacKinnon and O. Bertelsen and N. Bryan-Kinns},
   publisher = {British Computer Society},
   location = {Edinburgh, Scotland}
}

@inproceedings{gow-cadui2,
   title = {Computer Algebra in Interface Design Research},
   author = {Harold Thimbleby and Jeremy Gow},
   year = {2004},
   booktitle = {Proceedings of the Fifth ACM International Conference on Computer-Aided Design of User Interfaces --- {CADUI}'2004},
   location = {Funchal, Madeira}
}

Tools to design, analyse and evaluate user interfaces can be used in user interface design research and in interface modelling research. This demonstration shows two working systems: one in Mathematica that is mathematically sophisticated, and one as a ‘conventional’ rapid application development environment, where the mathematics is hidden, and which could form the basis of a professional design tool — but which is based rigorously on the same algebraic formalism.

@inproceedings{gow-cadui3,
   title = {Computer Algebra in Interface Design Research},
   author = {Harold Thimbleby and Jeremy Gow},
   abstract = {Tools to design, analyse and evaluate user interfaces can be used in user interface design research and in interface modelling research. This demonstration shows two working systems: one in Mathematica that is mathematically sophisticated, and one as a `conventional' rapid application development environment, where the mathematics is hidden, and which could form the basis of a professional design tool --- but which is based rigorously on the same algebraic formalism.},
   year = {2004},
   booktitle = {Proceedings 2004 {ACM/SIGCHI} International Conference on Intelligent User Interfaces --- {IUI}'04},
   pages = {366--367},
   isbn = {1-58113-815-6},
   url = {http://doi.acm.org/10.1145/964442.964537},
   editor = {N. J. Nunes and C. Rich},
   location = {Funchal, Madeira}
}

It is usually very hard, both for designers and users, to reason reliably about user interfaces. This paper shows that ‘push button’ and ‘point and click’ user interfaces are algebraic structures. Users effectively do matrix algebra when they interact, and therefore we can be precise about some important issues of usability. Matrices, in particular, are useful for explicit calculation and for proof of various user interface properties.

With matrix algebra, we are able to undertake with ease unusally thorough reviews of real user interfaces: this paper examines a mobile phone, a handheld calculator and a digital multimeter as case studies. All difficulties in applying the approach correspond to awkward or avoidable complexities in the user interfaces being modelled: using matrix algebra in design therefore encourages designers to avoid such user interface complexities.

@article{matrix-tochi,
   title = {User Interface Design with Matrix Algebra},
   author = {Harold Thimbleby},
   abstract = {It is usually very hard, both for designers and users, to reason reliably about user interfaces. This paper shows that `push button' and `point and click' user interfaces are algebraic structures. Users effectively do matrix algebra when they interact, and therefore we can be precise about some important issues of usability. Matrices, in particular, are useful for explicit calculation and for proof of various user interface properties. 

With matrix algebra, we are able to undertake with ease unusally thorough reviews of real user interfaces: this paper examines a mobile phone, a handheld calculator and a digital multimeter as case studies. All difficulties in applying the approach correspond to awkward or avoidable complexities in the user interfaces being modelled: using matrix algebra in design therefore encourages designers to avoid such user interface complexities.},
   year = {2004},
   pages = {181--236},
   journal = {ACM Transactions on Computer-Human Interaction},
   url = {http://cs.swan.ac.uk/~csharold/matrixweb/index.html},
   volume = {11},
   doi = {10.1145/1005361.1005364},
   number = {2}
}

@inproceedings{wali-bcs,
   title = {Evaluating a Novel Calculator Interface},
   author = {Harold Thimbleby and Paul Cairns and {\main{S. Wali}}},
   year = {2004},
   booktitle = {Proceedings British Computer Society {HCI} Conference},
   pages = {9--12},
   volume = {2},
   editor = {A. Dearden and L. Watts},
   publisher = {Research Press International}
}

@inproceedings{gow-cadui,
   title = {{MAUI}: An Interface Design Tool Based on Matrix Algebra},
   author = {Harold Thimbleby and Jeremy Gow},
   year = {2004},
   booktitle = {Proceedings of the Fifth ACM International Conference on Computer-Aided Design of User Interfaces IV --- {CADUI}'2004},
   pages = {81--94},
   isbn = {1--4020--3145--9},
   url = {http://cs.swan.ac.uk/~csharold/matrixweb/index.html},
   editor = {R. J. K. Jacob and Q. Limbourg and J. Vanderdonckt},
   publisher = {Kluwer Aacedmic Publishers},
   location = {Funchal, Maderia}
}

@inproceedings{HT48,
   title = {Integrating information seeking and structuring: Exploring the role of spatial hypertext in a digital library},
   author = {Harold Thimbleby and {\main{George Buchanan}} and M. Jones and Ann Blandford},
   year = {2004},
   booktitle = {Proceedings of the fifteenth ACM Conference on Hypertext and Hypermedia --- HT04},
   pages = {225--234},
   journal = {Proceedings of the European Conference on Digital Libraries},
   location = {Santa Cruz, CA, USA}
}

@inproceedings{HT49,
   title = {Supporting Information Structuring in a Digital Library},
   author = {Harold Thimbleby and {\main{George Buchanan}} and Ann Blandford and M. Jones},
   year = {2004},
   booktitle = {Proceedings {ECDL4}, European Conference on Digital Libraries},
   pages = {464--475},
   volume = {3232},
   publisher = {Springer Verlag},
   series = {Lecture Notes in Computer Science},
   editor = {R. Heery and L. Lyon}
}

@inproceedings{HT50,
   title = {Integrating Information Seeking and Structuring: Exploring the Role of Spatial Hypertexts in a Digital Library},
   author = {Harold Thimbleby and {\main{George Buchanan}} and Ann Blandford and M. Jones},
   year = {2004},
   booktitle = {Proceedings of the fifteenth ACM Conference on Hypertext and Hypermedia, HT'04},
   pages = {225--234},
   publisher = {ACM Press}
}

@inproceedings{affordance-nordichi,
   title = {Breaking Affordance: Culture as Context},
   author = {Harold Thimbleby and {\main{Lidia Oshlyansky}} and Paul Cairns},
   year = {October 23-27, 2004},
   booktitle = {Proceedings of 3rd. Nordic {ACM} Conference on Computer-Human Interaction --- NordiChi 2004},
   pages = {81--84},
   location = {Tampere, Finland}
}

@inproceedings{integrating,
   title = {Integrating Information Seeking and Structuring: Exploring the Role of Spatial Hypertext in a Digital Library},
   author = {Harold Thimbleby and {\main{George Buchanan}} and Ann Blandford and M. Jones},
   year = {2004},
   booktitle = {Proceedings Hypertext 2004, Fifteenth {ACM} Conference on Hypertext and Hypermedia --- HT04},
   pages = {225--234},
   highlight = {Winner of Ted Nelson Newcomer Award}
}

@inproceedings{careers-bcs,
   title = {Effective and Enjoyable Research Careers in {HCI}},
   author = {Harold Thimbleby},
   year = {2004},
   booktitle = {Proceedings British Computer Society {HCI} Conference},
   pages = {125--128},
   volume = {2},
   editor = {A. Dearden and L. Watts},
   publisher = {Research Press International}
}

@inproceedings{misleading-bcs,
   title = {Misleading Behaviour in Interactive Systems},
   author = {Harold Thimbleby and Jeremy Gow and Paul Cairns},
   year = {2004},
   booktitle = {Proceedings British Computer Society {HCI} Conference},
   pages = {33--36},
   volume = {2},
   editor = {A. Dearden and L. Watts},
   publisher = {Research Press International}
}

@inproceedings{diverse-bcs,
   title = {Supporting Diverse {HCI} Research},
   author = {Harold Thimbleby},
   year = {2004},
   booktitle = {Proceedings British Computer Society {HCI} Conference},
   pages = {125--128},
   volume = {2},
   editor = {A. Dearden and L. Watts},
   publisher = {Research Press International}
}

Formal methods in HCI are important, especially for safety critical systems, and of course for providing theory to underpin research. But formal methods are notoriously difficult, and the complexity of interactive systems that can be rigorously handled is limited. This paper shows how modern computer algebra systems can do some impressive mathematics that helps enormously in certain relevant areas of formalisation, such as in task/action mapping. Apart from learning how to use a computer algebra system, there is negligible craft knowledge — a new formal technique, as such, does not have to be learnt. One of the breakthroughs is the ability to generate formal interaction specifications, explore and generate theorems, from straight-forwardly programmed runnable animations; conventional iterative design can modify these implementations, and we can then automatically re-run the formal analyses.

@inproceedings{ca-bcs,
   title = {Computer Algebra in User Interface Design Analysis},
   author = {Harold Thimbleby},
   abstract = {Formal methods in {HCI} are important, especially for safety critical systems, and of course for providing theory to underpin research. But formal methods are notoriously difficult, and the complexity of interactive systems that can be rigorously handled is limited. This paper shows how modern computer algebra systems can do some impressive mathematics that helps enormously in certain relevant areas of formalisation, such as in task/action mapping. Apart from learning how to use a computer algebra system, there is negligible craft knowledge --- a new formal technique, as such, does not have to be learnt. One of the breakthroughs is the ability to generate formal interaction specifications, explore and generate theorems, from straight-forwardly programmed runnable animations; conventional iterative design can modify these implementations, and we can then automatically re-run the formal analyses.},
   year = {2004},
   booktitle = {Proceedings British Computer Society {HCI} Conference},
   pages = {121--124},
   url = {http://cs.swan.ac.uk/~csharold/CA/index.html},
   volume = {2},
   editor = {A. Dearden and L. Watts},
   publisher = {Research Press International}
}

Ensuring integrity between code and published papers so that algorithms can be written about reliably, whether for explaining them in scientific papers or books, requires automatic tool support. A versatile, light-weight approach that is easy to use is described.

(A Java implementation is available that works with Java, C and similar languages, and provides support for explanations in LaT_EX, XML, HTML, etc.)

@article{warp-spae,
   title = {Explaining Code for Publication},
   author = {Harold Thimbleby},
   abstract = {Ensuring integrity between code and published papers so that algorithms can be written about reliably, whether for explaining them in scientific papers or books, requires automatic tool support. A versatile, light-weight approach that is easy to use is described. 

(A Java implementation is available that works with Java, C and similar languages, and provides support for explanations in {\LaTeX}, XML, HTML, etc.)},
   year = {2003},
   pages = {975--1001},
   journal = {Software --- Practice {\&} Experience},
   url = {http://cs.swan.ac.uk/~csharold/warp/index.html},
   volume = {33},
   doi = {10.1002/spe.537},
   number = {10}
}

@article{web-iwc,
   title = {Improving Web Search on Small Screen Devices},
   author = {Harold Thimbleby and {\main{M. Jones}} and George Buchanan},
   year = {2003},
   pages = {479--495},
   journal = {Interacting with Computers},
   volume = {15},
   doi = {10.1016/S0953-5438(03)00036-5},
   number = {4}
}

Modern cryptography can achieve levels of security and authentication that non-specialists find literally incredible. Techniques including information-hiding protocols, zero-knowledge proofs and public key cryptosystems can be used to support applications like digital signatures, digital cash, on-line poker and secure voting in ways that are provably secure — far more secure than the traditional systems they replace. This paper describes simple versions of such applications that have been used to give school-children and the general public a broad understanding of what can be achieved, and how.

The material has been extensively and successfully used by the authors in schools, science festivals and with undergraduates, and even postgraduate specialists.

@article{HT2,
   title = {Explaining Cryptographic Systems},
   author = {Harold Thimbleby and T. Bell and M. Fellows and I. Witten and N. Koblitz and M. Powell},
   abstract = {Modern cryptography can achieve levels of security and authentication that non-specialists find literally incredible. Techniques including information-hiding protocols, zero-knowledge proofs and public key cryptosystems can be used to support applications like digital signatures, digital cash, on-line poker and secure voting in ways that are provably secure --- far more secure than the traditional systems they replace. This paper describes simple versions of such applications that have been used to give school-children and the general public a broad understanding of what can be achieved, and how. 

The material has been extensively and successfully used by the authors in schools, science festivals and with undergraduates, and even postgraduate specialists.},
   year = {2003},
   pages = {199--215},
   journal = {Computers {\&} Education},
   volume = {40},
   doi = {10.1016/S0360-1315(02)00102-1},
   number = {3}
}

A simple and efficient insert sort algorithm is presented in Java.

This paper uses warping (automatic code inclusion from actual program source) to ensure reliability of the published code; the code extracts in this paper are guaranteed compiled, run and tested. The preceding paper in this journal discusses both the tool warp and its rationale.

@article{warpsort-spae,
   title = {An Improved Insert Sort Algorithm},
   author = {Harold Thimbleby and O. Nevalainen and T. Raita},
   abstract = {A simple and efficient insert sort algorithm is presented in Java.

This paper uses warping (automatic code inclusion from actual program source) to ensure reliability of the published code; the code extracts in this paper are guaranteed compiled, run and tested. The preceding paper in this journal discusses both the tool warp and its rationale.},
   year = {2003},
   pages = {909--1001},
   journal = {Software --- Practice {\&} Experience},
   url = {http://cs.swan.ac.uk/~csharold/warp/index.html},
   volume = {33},
   number = {10}
}

@inproceedings{traps-bcs,
   title = {Understanding Interaction Traps},
   author = {Harold Thimbleby and {\main{Ann Blandford}} and N. Bryan-Kinns},
   year = {2003},
   booktitle = {Proceedings of BCS {HCI2--3}: Designing for Society},
   pages = {57--60},
   volume = {2}
}

This article describes a simplified cryptographic machine, based closely on the World War II Enigma. This ‘reduced Enigma’ exposes some of the design flaws of the original Enigma in a new way. Had the Axis powers built a reduced Enigma, the outcome of the war might have been different.

A fully working reduced Enigma has been used very successfully in numerous public lectures, in school talks, and in university seminars. Hands-on demonstrations of the reduced Enigma dramatically brings alive ideas about design, codes, permutations and groups. As a working trapdoor function, the reduced Enigma also provides an unusually clear introduction to public key cryptography. This article provides background information, lecture suggestions, and details for building it.

@article{enigma,
   title = {The Reduced Enigma},
   author = {Harold Thimbleby},
   abstract = {This article describes a simplified cryptographic machine, based closely on the World War II Enigma. This `reduced Enigma' exposes some of the design flaws of the original Enigma in a new way. Had the Axis powers built a reduced Enigma, the outcome of the war might have been different.

A fully working reduced Enigma has been used very successfully in numerous public lectures, in school talks, and in university seminars. Hands-on demonstrations of the reduced Enigma dramatically brings alive ideas about design, codes, permutations and groups. As a working trapdoor function, the reduced Enigma also provides an unusually clear introduction to public key cryptography. This article provides background information, lecture suggestions, and details for building it.},
   year = {2003},
   pages = {624--642},
   journal = {Computers {\&} Security},
   url = {http://cs.swan.ac.uk/~csharold/enigma/index.html},
   volume = {22},
   number = {7},
   doi = {10.1016/S0167-4048(03)00712-0}
}

The Chinese Postman Problem has many applications, including robot exploration, and analysing interactive system and Web site usability. This paper reviews the wide range of applications of the problem and presents complete, executable code to solve it for the case of directed multigraphs. A variation called the “open Chinese Postman Problem” is also introduced and solved. Although optimizations are possible, no substantially better algorithms are likely.

@article{dcc-spae,
   title = {The Directed Chinese Postman Problem},
   author = {Harold Thimbleby},
   abstract = {The Chinese Postman Problem has many applications, including robot exploration, and analysing interactive system and Web site usability. This paper reviews the wide range of applications of the problem and presents complete, executable code to solve it for the case of directed multigraphs. A variation called the ``open Chinese Postman Problem'' is also introduced and solved. Although optimizations are possible, no substantially better algorithms are likely.},
   year = {2003},
   pages = {1081--1096},
   journal = {Software --- Practice {\&} Experience},
   url = {http://cs.swan.ac.uk/~csharold/cpp/index.html},
   volume = {33},
   doi = {10.1002/spe.540},
   number = {11}
}

@inproceedings{HT52,
   title = {Spatial Hypertext as a Reader Tool in Digital Libraries},
   author = {Harold Thimbleby and {\main{George Buchanan}} and A. E. Blandford and M. Jones},
   year = {2002},
   booktitle = {Proceedings Visual Interfaces to Digital Libraries},
   pages = {13--24},
   volume = {2539},
   editor = {K. B{\"o}rner and C. Chen},
   publisher = {Springer Verlag},
   series = {Lecture Notes in Computer Science}
}

When designing complex systems, it is standard systems engineering practice to carefully design the interfaces between subsystems. Yet when designing human/computer systems, the interface between human and system is not usually thought through in such terms. Instead, the human is often given wide access to arbitrary parts of the system, and the result is a complex human/computer system that fails in various ways.

We illustrate this argument with a case study of a public walk-up-and-use rail ticketing system. We show that the interaction imposed on the user is inappropriate to the user’s task needs; we show how user interface problems arise through access to organisational conventions that are of little interest to users. Furthermore, the wide interface is beyond the resources of the rail organisation to manage.

Conversely we show that an interface designed to hide irrelevant complexity (exactly as one would do approaching user interfaces as a systems engineering design problem) can have a beneficial impact on the user experience, including improving the reliability of the total system.

@inproceedings{ticket-bcs,
   title = {User Interface Design as Systems Design},
   author = {Harold Thimbleby and Ann Blandford and Paul Cairns and P. Curzon and M. Jones},
   abstract = {When designing complex systems, it is standard systems engineering practice to carefully design the interfaces between subsystems. Yet when designing human/computer systems, the interface between human and system is not usually thought through in such terms. Instead, the human is often given wide access to arbitrary parts of the system, and the result is a complex human/computer system that fails in various ways. 

We illustrate this argument with a case study of a public walk-up-and-use rail ticketing system. We show that the interaction imposed on the user is inappropriate to the user's task needs; we show how user interface problems arise through access to organisational conventions that are of little interest to users. Furthermore, the wide interface is beyond the resources of the rail organisation to manage. 

Conversely we show that an interface designed to hide irrelevant complexity (exactly as one would do approaching user interfaces as a systems engineering design problem) can have a beneficial impact on the user experience, including improving the reliability of the total system.},
   year = {2002},
   booktitle = {Proceedings People and Computers --- Memorable Yet Invisible},
   pages = {281--301},
   url = {http://cs.swan.ac.uk/~csharold/tvm},
   volume = {XVI},
   editor = {X. Faulkner and J. Finlay and F. D{\'e}tienne},
   publisher = {Springer Verlag},
   location = {London}
}

@inproceedings{HT53,
   title = {The New Usability: The Challenge of Designing for Pervasive Computing},
   author = {Harold Thimbleby and P. Thomas},
   year = {2002},
   booktitle = {Proceedings of the {ICCC2002}, 15th. International Conference on Computer Communication},
   pages = {382--388},
   editor = {S. V. Raghavan and S. P. Mudur}
}

The continual failure of personal technology highlights the growing problem of obsolete, irreparable and non-recyclable toxic waste. Moore’s Law is a symptom of failure as much as a promise of better technology. Better design could avoid the problems.

@article{HT4,
   title = {Obituary for a Fax},
   author = {Harold Thimbleby and M. Jones},
   abstract = {The continual failure of personal technology highlights the growing problem of obsolete, irreparable and non-recyclable toxic waste. Moore's Law is a symptom of failure as much as a promise of better technology. Better design could avoid the problems.},
   year = {2002},
   pages = {151--152},
   journal = {Personal Technologies},
   volume = {6},
   number = {2}
}

Small handheld devices — mobile phones, PDAs etc — are increasingly being used to access the Web. Search engines are the most used Web services and are an important user support. Recently, Google (and other search engine providers) have started to offer their services on the small screen.

This paper presents a detailed evaluation of the how easy to use such services are in these new contexts. An experiment was carried out to compare users’ abilities to complete realistic tourist orientated search tasks using a WAP, PDA-sized and conventional, desktop interface to the full Google index. With all three interfaces, when users succeed in completing a task, they do so quickly (within 2 to 3 minutes) and using few interactions with the search engine. When they fail, though, they fail badly. The paper examines the causes of failures in small screen searching and proposes guidelines for improving these interfaces.

@inproceedings{HT51,
   title = {Sorting out Searching on Small Screen Devices},
   author = {Harold Thimbleby and {\main{M. Jones}} and George Buchanan},
   abstract = {Small handheld devices --- mobile phones, PDAs etc --- are increasingly being used to access the Web. Search engines are the most used Web services and are an important user support. Recently, Google (and other search engine providers) have started to offer their services on the small screen.

This paper presents a detailed evaluation of the how easy to use such services are in these new contexts. An experiment was carried out to compare users' abilities to complete realistic tourist orientated search tasks using a WAP, PDA-sized and conventional, desktop interface to the full Google index. With all three interfaces, when users succeed in completing a task, they do so quickly (within 2 to 3 minutes) and using few interactions with the search engine. When they fail, though, they fail badly. The paper examines the causes of failures in small screen searching and proposes guidelines for improving these interfaces.},
   year = {2002},
   booktitle = {Proceedings 4th. International Symposium, Mobile Human-Computer Interaction {HCI} 2002},
   pages = {81--94},
   volume = {2411},
   publisher = {Springer Verlag},
   series = {Lecture Notes in Computer Science}
}

@article{HT3,
   title = {Data Structures in the Design of Interfaces},
   author = {Harold Thimbleby and {\main{G. Marsden}} and M. Jones and P. Gillary},
   year = {2002},
   pages = {132--140},
   journal = {Personal and Ubiquitous Computing},
   volume = {6},
   number = {2}
}

How hard do users find interactive devices to use to achieve their goals, and how can we get this information early enough to influence design?

We show that Markov modelling can obtain suitable measures, and we provide formulas that can be used for a large class of systems. We analyse and consider alternative designs for various examples. We introduce a “usability/knowledge graph,” and we show that a device that is “obviously” easy to use probably isn’t.

Markov models can be evaluated in suitable mathematical packages; Mathematica (one such package) can very conveniently simulate the device being evaluated: mathematical and empirical analysis may be combined. One would hope that in the future, design tools would include such mathematical analysis, and no new design skills would be required to evaluate devices. (This paper provides complete code in an Appendix.)

@article{markov-tochi,
   title = {Usability Analysis with Markov Models},
   author = {Harold Thimbleby and Paul Cairns and M. Jones},
   abstract = {How hard do users find interactive devices to use to achieve their goals, and how can we get this information early enough to influence design?

We show that Markov modelling can obtain suitable measures, and we provide formulas that can be used for a large class of systems. We analyse and consider alternative designs for various examples. We introduce a ``usability/knowledge graph,'' and we show that a device that is ``obviously'' easy to use probably isn't. 

Markov models can be evaluated in suitable mathematical packages; {\emph{Mathematica\/}} (one such package) can very conveniently simulate the device being evaluated: mathematical and empirical analysis may be combined. One would hope that in the future, design tools would include such mathematical analysis, and no new design skills would be required to evaluate devices. (This paper provides complete code in an Appendix.)},
   year = {2001},
   pages = {99--132},
   journal = {ACM Transactions on Computer-Human Interaction},
   url = {http://cs.swan.ac.uk/~csharold/Markov/index.html},
   volume = {8},
   number = {2}
}

Computer viruses are a worrying real-world problem, and a challenge to theoretical modelling. In this issue of the Computer Journal, Erkki Mäkinen proposes universal Turing machines in a critique of an earlier paper, “A framework for modelling Trojans and computer virus infection” (H. Thimbleby, S. O. Anderson and P. A. Cairns, Comp. J., 41(7):444–458, 1999). This short paper is a reply by those authors.

@article{comment-cj,
   title = {Reply to `Comment on ``A Framework for Modelling Trojans and Computer Virus Infection'', by E. M{\"a}kinen},
   author = {Harold Thimbleby and S. O. Anderson and P. A. Cairns},
   abstract = {Computer viruses are a worrying real-world problem, and a challenge to theoretical modelling. In this issue of the {\emph{Computer Journal}}, Erkki M{\"a}kinen proposes universal Turing machines in a critique of an earlier paper, ``A framework for modelling Trojans and computer virus infection'' (H. Thimbleby, S. O. Anderson and P. A. Cairns, {\emph{Comp. J.}}, {\textbf{41}}(7):444--458, 1999). This short paper is a reply by those authors.},
   year = {2001},
   pages = {324--325},
   journal = {Computer Journal},
   volume = {44},
   number = {4}
}

User interfaces often only support one way to do a task when the physical interface or the logic of the task would permit other ways. In contrast, a user interface that supports multiple approaches is permissive. This paper argues that permissive user interfaces are easier to use — and even when they are not applicable for particular applications, considering permissiveness is a productive design heuristic.

@article{permissive-ijhcs,
   title = {Permissive User Interfaces},
   author = {Harold Thimbleby},
   abstract = {User interfaces often only support one way to do a task when the physical interface or the logic of the task would permit other ways. In contrast, a user interface that supports multiple approaches is {\emph{permissive\/}}. This paper argues that permissive user interfaces are easier to use --- and even when they are not applicable for particular applications, considering permissiveness is a productive design heuristic.},
   year = {2001},
   pages = {333--350},
   journal = {International Journal of Human-Computer Studies},
   volume = {54},
   number = {3}
}

This paper describes preliminary work carried out to design a children’s digital library of stories and poems with and for children aged 11-14 years old. We describe our experience in engaging children as design partners, and propose a digital library environment and design features to provide an engaging, successful learning experience for children using it for collaborative writing.

@inproceedings{HT54,
   title = {Dynamic Digital Libraries For Children},
   author = {Harold Thimbleby and {\main{Y-L. Theng}} and N. Mohd-Nasir and George Buchanan and B. Fields and N. Cassidy},
   abstract = {This paper describes preliminary work carried out to design a children's digital library of stories and poems with and for children aged 11-14 years old. We describe our experience in engaging children as design partners, and propose a digital library environment and design features to provide an engaging, successful learning experience for children using it for collaborative writing.},
   year = {2001},
   booktitle = {The First {ACM+IEEE} Joint Conference on Digital Libraries, {JCDL}},
   pages = {406--415}
}

@inproceedings{HT56,
   title = {Improving Mobile Internet Usability},
   author = {Harold Thimbleby and George Buchanan and S. Farrant and {\main{M. Jones}} and G. Marsden and M. Pazzani},
   year = {2001},
   booktitle = {Proceedings 10th. World Wide Web Conference --- WWW10},
   pages = {673--680},
   location = {Hong Kong}
}

@inproceedings{HT55,
   title = {Just Programming},
   author = {Harold Thimbleby and P. Duquenoy},
   year = {2001},
   booktitle = {Proceedings 5th. Ethicomp, The Social and Ethical Impacts of Information and Communication Technologies},
   pages = {83--91},
   editor = {T. W. Bynum and H. Krawczy and S. Rogerson and S. Szejko and B. Wiszniewski}
}

In the two decades hand-held calculators have been readily available there has been ample time to develop a usable design and to educate the consumer public into choosing quality devices. This article reviews a representative calculator that is ‘state of the art’ and shows it has an execrable design. The design is shown to be confusing and essentially non-mathematical. Substantial evidence is presented that illustrates the inadequate documentation, bad implementation, feature interaction, and feature incoherence. These problems are shown to be typical of calculators generally. Despite the domain (arithmetic) being well-defined, the design problems are profound, widespread, confusing — and needless. Worrying questions are begged: about design quality control, about consumer behaviour, and about the role of education — both at school level (training children to acquiesce to bad design) and at university level (training professionals to design unusable products). The article concludes with recommendations.

@article{needless-ijhcs,
   title = {Calculators are Needlessly Bad},
   author = {Harold Thimbleby},
   abstract = {In the two decades hand-held calculators have been readily available there has been ample time to develop a usable design and to educate the consumer public into choosing quality devices. This article reviews a representative calculator that is `state of the art' and shows it has an execrable design. The design is shown to be confusing and essentially non-mathematical. Substantial evidence is presented that illustrates the inadequate documentation, bad implementation, feature interaction, and feature incoherence. These problems are shown to be typical of calculators generally. Despite the domain (arithmetic) being well-defined, the design problems are profound, widespread, confusing --- and needless. Worrying questions are begged: about design quality control, about consumer behaviour, and about the role of education --- both at school level (training children to acquiesce to bad design) and at university level (training professionals to design unusable products). The article concludes with recommendations.},
   year = {2000},
   pages = {1031--1069},
   journal = {International Journal of Human-Computer Studies},
   url = {http://cs.swan.ac.uk/~csharold/calculators/index.html},
   volume = {52},
   number = {6}
}

As a result of the popularity of graphical user interfaces, it is now almost impossible to buy a programming language compiler, instead, one purchases a development environment. Of course, we can scoff at the distinction and say that a development environment is nothing more than a programming language with visual (as opposed to syntactic) sugar. We believe, however, that this view must change if safer and more responsible programming languages are to be created for the next generation of programmer. Within this paper, we will argue that a more theoretical approach should be taken to the development of programming environments and suggest ways in which this may be achieved.

@article{HT5,
   title = {Holistic Programming Environments},
   author = {Harold Thimbleby and {\main{G. Marsden}}},
   abstract = {As a result of the popularity of graphical user interfaces, it is now almost impossible to buy a programming language compiler, instead, one purchases a development environment. Of course, we can scoff at the distinction and say that a development environment is nothing more than a programming language with visual (as opposed to syntactic) sugar. We believe, however, that this view must change if safer and more responsible programming languages are to be created for the next generation of programmer. Within this paper, we will argue that a more theoretical approach should be taken to the development of programming environments and suggest ways in which this may be achieved.},
   year = {2000},
   pages = {237--241},
   journal = {South African Computer Journal},
   volume = {26},
   issn = {1015-7999}
}

@inproceedings{HT61,
   title = {On Discerning Users},
   author = {Harold Thimbleby},
   year = {2000},
   booktitle = {How to make User Centred Design Usable},
   pages = {63--78},
   editor = {J. Gulliksen and A. Lantz and I. Boivie},
   series = {TRITA-NA-D0006, CID-72},
   location = {KTH, Stockholm, Sweden}
}

Exploiting standard computer science algorithms, we designed a more efficient user interface for a mobile phone. In experiments, the new design was found to be not only more efficient but preferred by users.

@inproceedings{uid-chi,
   title = {Successful User Interface Design from Efficient Computer Algorithms},
   author = {Harold Thimbleby and {\main{G. Marsden}} and P. Gillary and M. Jones},
   abstract = {Exploiting standard computer science algorithms, we designed a more efficient user interface for a mobile phone. In experiments, the new design was found to be not only more efficient but preferred by users.},
   year = {2000},
   booktitle = {Proceedings {ACM} {CHI} (Extended Abstracts)},
   pages = {181--182}
}

@inproceedings{trust-chi,
   title = {Non-contractual Trust},
   author = {Harold Thimbleby and {\main{E. Davenport}} and M. Dibben and B. Friedman and S. P. Marsh and H. Rosenbaum},
   year = {2000},
   booktitle = {Proceedings {ACM} {CHI} (Extended Abstracts)},
   note = {Design, and Human Computer Interactions},
   pages = {239--240},
   location = {Amsterdam, Holland}
}

User interfaces are bad and not getting better. Users would be empowered by usability certificates, so they could make informed choices when purchasing complex equipment, and hence apply market pressure to improve quality. A clear labelling scheme is required to enable consumer action.

@inproceedings{cert-bcs,
   title = {Empowering Users with Usability Certificates},
   author = {Harold Thimbleby and M. Jones and G. Marsden},
   abstract = {User interfaces are bad and not getting better. Users would be empowered by {\emph{usability certificates\/}}, so they could make informed choices when purchasing complex equipment, and hence apply market pressure to improve quality. A clear labelling scheme is required to enable consumer action.},
   year = {2000},
   booktitle = {Human Computer Interaction 2000, Proceedings British Computer Society Conference on Human-Computer Interaction},
   pages = {37--38},
   isbn = {1--902505--35--2},
   volume = {II},
   editor = {S. Turner and P. Turner},
   location = {Newcastle, England}
}

By taking a mobile phone as a worked example, we show how it and new interfaces can be analysed and simulated. A new interface is shown to reduce the optimal key press costs of accessing the phone’s functionality, without losing usability benefits — this is a specific contribution to menu design. However, the approach is not limited to mobile phones, nor just to menus; the techniques are general and can be applied widely. A distinctive feature of the approach is that it is fully inspectable and replicable — this is a contribution to the field of HCI more generally.

@inproceedings{ansim-bcs,
   title = {Analysis and Simulation of User Interfaces},
   author = {Harold Thimbleby},
   abstract = {By taking a mobile phone as a worked example, we show how it and new interfaces can be analysed and simulated. A new interface is shown to reduce the optimal key press costs of accessing the phone's functionality, without losing usability benefits --- this is a specific contribution to menu design. However, the approach is not limited to mobile phones, nor just to menus; the techniques are general and can be applied widely. A distinctive feature of the approach is that it is fully inspectable and replicable --- this is a contribution to the field of HCI more generally.},
   year = {2000},
   booktitle = {Human Computer Interaction 2000, Proceedings British Computer Society Conference on Human-Computer Interaction},
   pages = {221--237},
   isbn = {1--85233--318--9},
   volume = {XIV},
   editor = {S. McDonald and Y. Waern and G. Cockton},
   location = {Newcastle, England}
}

@inproceedings{HT59,
   title = {Designing a Children's Digital Library with and for Children},
   author = {Harold Thimbleby and {\main{Y. L. Theng}} and N. Mohd-Nasir and George Buchanan and M. Jones},
   year = {2000},
   booktitle = {Proceedings of the ACM Fifth Digital Library Conference},
   pages = {266--267}
}

@inproceedings{HT58,
   title = {Interaction Modelling for Digital Libraries},
   author = {Harold Thimbleby and N. Bryan-Kinns and A. E. Blandford},
   year = {2000},
   booktitle = {Proceedings Workshop on Evaluation of Information Management Systems},
   pages = {1--10}
}

@inproceedings{HT57,
   title = {Children as Design Partners and Testers for a Children's Digital Library},
   author = {Harold Thimbleby and {\main{Y. L. Theng}} and N. Mohd-Nasir and George Buchanan and M. Jones and D. Bainbridge and N. Cassidy},
   year = {2000},
   booktitle = {Proceedings 4th. European Conference on Research and Advanced Technology for Digital Libraries, ECDL 2000},
   pages = {249--258},
   volume = {1923},
   editor = {J. Borbinha and T. Baker},
   publisher = {Springer Verlag},
   series = {Lecture Notes in Computer Science}
}

A preliminary study was conducted to help understand the purpose of digital libraries (DLs) and to investigate whether meaningful results could be obtained from small user studies of digital libraries. Results stress the importance of mental models, and of “traditional” library support.

@inproceedings{HT60,
   title = {Purpose and Usability of Digital Libraries},
   author = {Harold Thimbleby and {\main{Y. L. Theng}} and George Buchanan and N. Mohd-Nasir},
   abstract = {A preliminary study was conducted to help understand the purpose of digital libraries (DLs) and to investigate whether meaningful results could be obtained from small user studies of digital libraries. Results stress the importance of mental models, and of ``traditional'' library support.},
   year = {2000},
   booktitle = {Proceedings Fifth {ACM} Conference on Digital Libraries, {ACM} {DL}'2000},
   pages = {238--239},
   location = {San Antonio, Texas}
}

This paper describes a usability tool implemented to demonstrate that meaningful results could be obtained from small user studies.

@inproceedings{HT110,
   title = {A Usability Tool for Web Evaluation applied to Digital Library Design},
   author = {Harold Thimbleby and Y. L. Theng and N. Mohd Nasir},
   abstract = {This paper describes a usability tool implemented to demonstrate that meaningful results could be obtained from small user studies.},
   year = {May 15-19, 2000},
   booktitle = {World Wide Web Conference --- {WWW9} Poster Proceedings},
   pages = {90--91},
   location = {Amsterdam}
}

The design of car (automobile) radios exposes ethical issues in the design of consumer electronics. We show that car radios, despite being manufactured for many years and being a well-understood technology, are unsafe to use. It is implausible that manufacturers design such unsafe devices unwittingly. We argue that complex in-car devices raise clear ethical issues:

• their complexity of operation demands and diverts driver attention from road safety (social ethics — social responsibility)
• the values embedded in their design (e.g., marketing values, seductive styling) are not consistent with their function (design ethics — issues of professional responsibility)

Further, we show there is a correspondence between theories of justice and these ethical issues.

@inproceedings{HT63,
   title = {Ethics and Consumer Electronics},
   author = {Harold Thimbleby and G. Marsden and P. Duquenoy},
   abstract = {The design of car (automobile) radios exposes ethical issues in the design of consumer electronics. We show that car radios, despite being manufactured for many years and being a well-understood technology, are unsafe to use. It is implausible that manufacturers design such unsafe devices unwittingly. We argue that complex in-car devices raise clear ethical issues: {\begin{itemize}}{\item} their complexity of operation demands and diverts driver attention from road safety (social ethics --- social responsibility) {\item} the values embedded in their design (e.g., marketing values, seductive styling) are not consistent with their function (design ethics --- issues of professional responsibility) {\end{itemize}}

Further, we show there is a correspondence between theories of justice and these ethical issues.},
   year = {1999},
   booktitle = {Proceedings of the 4th. {ETHICOMP} International Conference on the Social and Ethical Impacts of Information and Communication Technologies, Ethicomp'99},
   isbn = {88--900396--0--4},
   editor = {A. D'Atri and A. Marturano and S. Rogerson and T. Ward Bynum}
}

@inproceedings{HT62,
   title = {Towards a Synthesis of Discourse Ethics and Internet Regulation},
   author = {Harold Thimbleby and {\main{P. Duquenoy}} and S. Torrance},
   year = {1999},
   booktitle = {Proceedings of the 4th. {ETHICOMP} International Conference on the Social and Ethical Impacts of Information and Communication Technologies, Ethicomp'99},
   isbn = {88--900396--0--4},
   editor = {A. D'Atri and A. Marturano and S. Rogerson and T. Ward Bynum}
}

@inproceedings{principles-interact,
   title = {Using Computing Science Principles in Interface Design},
   author = {Harold Thimbleby and G. Marsden and P. Gillary and M. Jones},
   year = {1999},
   booktitle = {Proceedings IFIP Conference on {Human-Computer} Interaction --- Interact 1999},
   pages = {47--48},
   isbn = {1--902505--19-0},
   volume = {2},
   editor = {S. Brewster and A. Cawsey and G. Cockton}
}

It is not possible to view a computer operating in the real world, including the possibility of Trojan Horse programs and computer viruses, as simply a finite realisation of a Turing Machine. We consider the actions of Trojan Horses and viruses in real computer systems and suggest a minimal framework for an adequate formal understanding of the phenomena. Some conventional approaches, including biological metaphors, are shown to be inadequate; some suggestions are made towards constructing virally-resistant systems.

@article{framework-cj,
   title = {A Framework for Modelling Trojans and Computer Virus Infection},
   author = {Harold Thimbleby and S. O. Anderson and Paul Cairns},
   abstract = {It is not possible to view a computer operating in the real world, including the possibility of Trojan Horse programs and computer viruses, as simply a finite realisation of a Turing Machine. We consider the actions of Trojan Horses and viruses in real computer systems and suggest a minimal framework for an adequate formal understanding of the phenomena. Some conventional approaches, including biological metaphors, are shown to be inadequate; some suggestions are made towards constructing virally-resistant systems.},
   year = {1999},
   pages = {444--458},
   journal = {Computer Journal},
   volume = {41},
   number = {7}
}

Our experience of using Java is disappointing: as a programming language (irrespective of its implementations and libraries) Java itself leaves much to be desired. This paper discusses a few serious problems with Java’s design, which leads us to suggest that the language definition should have been an integral part of the design process rather than, as appears, a retrospective commentary.

@article{java-spae,
   title = {A Critique of Java},
   author = {Harold Thimbleby},
   abstract = {Our experience of using Java is disappointing: as a programming language (irrespective of its implementations and libraries) Java itself leaves much to be desired. This paper discusses a few serious problems with Java's design, which leads us to suggest that the language definition should have been an integral part of the design process rather than, as appears, a retrospective commentary.},
   year = {1999},
   pages = {457--478},
   journal = {Software --- Practice {\&} Experience},
   volume = {29},
   number = {5}
}

This paper shows how to combine a substantial part of the product development cycle of interactive devices into a single, co-ordinated approach. Much can be derived automatically from a suitable specification of the interactive device, and it can be derived automatically. Normal product development has a device specified and built, then has its manuals written, then it is used and tested. At this late stage design problems may be identified, but it is now too late: usability studies become academic in so far as the particular product is concerned, since it is already effectively in production. It would be better if the testing and manual writing could rapidly be obtained from the initial specification, before any investment has been made in fabrication. This paper offers a design approach that achieves this, and it shows how the various views of the design can be used help improve each other — for instance, the automatically generated user manual can be fed back to suggest improvements in the design.

A microwave cooker is used as a real example. However, this paper provides full and unabridged details of everything it discusses by using Mathematica as a rapid prototyping environment. Any similar device can be analysed in the same way, directly from the paper.

This paper is based on H. Thimbleby, “Specification-led Design,” Living Life to the Full with Personal Technologies, IEE Digest No 98/268, pp4/1-4/9, 1998.

@article{HT6,
   title = {Specification-led Design for Interface Simulation, Collecting Use-data, Interactive Help, Writing Manuals, Analysis, Comparing Alternative Designs, etc},
   author = {Harold Thimbleby},
   abstract = {This paper shows how to combine a substantial part of the product development cycle of interactive devices into a single, co-ordinated approach. Much can be derived automatically from a suitable specification of the interactive device, and it can be derived automatically. Normal product development has a device specified and built, then has its manuals written, then it is used and tested. At this late stage design problems may be identified, but it is now too late: usability studies become academic in so far as the particular product is concerned, since it is already effectively in production. It would be better if the testing and manual writing could rapidly be obtained from the initial specification, before any investment has been made in fabrication. This paper offers a design approach that achieves this, and it shows how the various views of the design can be used help improve each other --- for instance, the automatically generated user manual can be fed back to suggest improvements in the design.

A microwave cooker is used as a real example. However, this paper provides full and unabridged details of everything it discusses by using Mathematica as a rapid prototyping environment. Any similar device can be analysed in the same way, directly from the paper.

This paper is based on H. Thimbleby, ``Specification-led Design,'' {\emph{Living Life to the Full with Personal Technologies}}, IEE Digest No 98/268, pp4/1-4/9, 1998.},
   year = {1999},
   pages = {241--254},
   journal = {Personal Technologies},
   url = {http://cs.swan.ac.uk/~csharold/ansim/index.html},
   volume = {4},
   number = {2}
}

Within the field of HCI there are a number of preferred approaches towards design. As within other disciplines, these approaches are often irreconcilable. We explore the possibilities of using ethics as a way to bridge the gap and re-establish the design focus of doing good towards the user. This is the idea of ‘justice’ to aid improved design. According to Aristotle, justice is classed as a virtue: to do justice is to act for the good, which is what is wanted for good HCI design. John Rawls’ classic A Theory of Justice, (1971) talks about justice as fairness, and it is in this context we apply justice to the area of design. We show some surprising links with HCI practice, and hence suggest some new perspectives on HCI.

@inproceedings{justice-interact,
   title = {Justice and Design},
   author = {Harold Thimbleby and P. Duquenoy},
   abstract = {Within the field of HCI there are a number of preferred approaches towards design. As within other disciplines, these approaches are often irreconcilable. We explore the possibilities of using ethics as a way to bridge the gap and re-establish the design focus of doing good towards the user. This is the idea of `justice' to aid improved design. According to Aristotle, justice is classed as a virtue: to do justice is to act for the good, which is what is wanted for good HCI design. John Rawls' classic {\emph{A Theory of Justice\/}}, (1971) talks about justice as fairness, and it is in this context we apply justice to the area of design. We show some surprising links with HCI practice, and hence suggest some new perspectives on HCI.},
   year = {1999},
   booktitle = {Proceedings {IFIP} Conference on Human-Computer Interaction --- Interact 1999},
   pages = {281--286},
   isbn = {0--9673355--0--7},
   editor = {M. A. Sasse and C. Johnson}
}

@inproceedings{HT111,
   title = {A Usability Tool for Digital Libraries},
   author = {Harold Thimbleby and {\main{Y. L. Theng}} and N. Mohd-Nasir},
   year = {1999},
   booktitle = {Proceedings 9th. International World Wide Web Conference --- WWW9 Poster Proceedings},
   pages = {90--91},
   location = {Toronto}
}

@inproceedings{web-interact,
   title = {How do We Build Web Sites Fit for Purpose?},
   author = {Harold Thimbleby and George Buchanan and G. Marsden and Y. L. Theng},
   year = {1999},
   booktitle = {Proceedings IFIP Conference on {Human-Computer Interaction} --- Interact 1999},
   pages = {11--12},
   isbn = {1--902505--19-0},
   volume = {2},
   editor = {S. Brewster and A. Cawsey and G. Cockton}
}

As current digital libraries are becoming more complex, the facilities provided by them will increase and the difficulty of learning associated with the complexity of using these facilities will also increase. In order to produce usable and useful interactive systems, designers need to ensure that good design features are incorporated into the systems, taking into consideration end-users’ needs and cultural backgrounds. We carried out a study to investigate useful design features of digital libraries for task completion and end-user’s perceived impressions on the effectiveness of the digital libraries. The results also suggest that there is little provision on the interface to cater to end-users’ browsing and inter-cultural needs. Hence, this paper also discusses design guidelines for the design of user-centred digital libraries.

@inproceedings{HT67,
   title = {Design Guidelines and User-Centred Digital Libraries},
   author = {Harold Thimbleby and Y. L. Theng and E. Duncker and N. Mohd Nasir and George Buchanan},
   abstract = {As current digital libraries are becoming more complex, the facilities provided by them will increase and the difficulty of learning associated with the complexity of using these facilities will also increase. In order to produce usable and useful interactive systems, designers need to ensure that good design features are incorporated into the systems, taking into consideration end-users' needs and cultural backgrounds. We carried out a study to investigate useful design features of digital libraries for task completion and end-user's perceived impressions on the effectiveness of the digital libraries. The results also suggest that there is little provision on the interface to cater to end-users' browsing and inter-cultural needs. Hence, this paper also discusses design guidelines for the design of user-centred digital libraries.},
   year = {1999},
   booktitle = {Proceedings Third European Conference on Digital Libraries ECDL'99: Research and Advanced Technology for Digital Libraries},
   pages = {167--183},
   series = {Lecture Notes in Computer Science},
   editor = {S. Abiteboul and A. Vercoustre},
   publisher = {Springer Verlag}
}

@article{HT113,
   title = {Towards a Usermetric Tool to Improve Web Accessibility},
   author = {Harold Thimbleby and {\main{Y. L. Theng}}},
   year = {1999},
   booktitle = {Proceedings 8th. International World Wide Web Conference --- WWW8 Poster Proceedings},
   note = {Poster Proceedings},
   pages = {152--153},
   publisher = {Fortec Seminars},
   location = {Toronto}
}

@article{morality-interact,
   title = {`Artificial Morality': Representations of Trust in Interactive Systems?},
   author = {Harold Thimbleby and E. Davenport and {\main{S. P. Marsh}} and M. Dibben},
   year = {1999},
   pages = {211--213},
   isbn = {1--902505--19-0},
   journal = {Proceedings IFIP Conference on Human-Computer Interaction --- Interact 1999},
   volume = {2},
   editor = {S. Brewster and A. Cawsey and G. Cockton}
}

@inproceedings{HT64,
   title = {Design Guidelines and User-centred Digital Libraries},
   author = {Harold Thimbleby and {\main{Y. L. Theng}} and E. Dunker and N. Mohd-Nasir and George Buchanan},
   year = {1999},
   booktitle = {Proceedings Research and Advanced Technology for Digital Libraries, Third European Conference on Digital Libraries, {ECDL'99}},
   pages = {167--183},
   volume = {1696},
   editor = {S. Abiteboul and A-M. Vercoustre},
   series = {Lecture Notes in Computer Science},
   publisher = {Springer Verlag}
}

@inproceedings{HT66,
   title = {A Stable View of the Hyperactive Web},
   author = {Harold Thimbleby and George Buchanan and G. Marsden and T. Tan and Y-L. Theng},
   year = {1999},
   booktitle = {Proceedings Workshop on The Active Web},
   pages = {27--33},
   isbn = {1--897898--45--2},
   editor = {D. Clarke and A. Dix and F. Dix}
}

Modern cryptography can achieve levels of security and authentication that non-specialists find literally incredible. Techniques include information-hiding protocols, zero-knowledge proofs and public key cryptosystems; they can be used to support applications like digital signatures, digital cash, on-line poker and secure voting in ways that are provably secure — far more secure than the traditional systems they replace. This paper describes simple versions of such applications that have been used to give school-children and the general public a broad understanding of what can be achieved, and how.

@inproceedings{HT122,
   title = {Explaining Cryptosystems to the General Public},
   author = {Harold Thimbleby and T. Bell and M. Fellows and I. Witten and N. Koblitz},
   abstract = {Modern cryptography can achieve levels of security and authentication that non-specialists find literally incredible. Techniques include information-hiding protocols, zero-knowledge proofs and public key cryptosystems; they can be used to support applications like digital signatures, digital cash, on-line poker and secure voting in ways that are provably secure --- far more secure than the traditional systems they replace. This paper describes simple versions of such applications that have been used to give school-children and the general public a broad understanding of what can be achieved, and how.},
   year = {1999},
   booktitle = {Proceedings IFIP TC11 WG11.8 Conference},
   aftertitle = {Keynote},
   pages = {221--233},
   isbn = {91--7153--910--7},
   editor = {L. Yngstgr{\"o}m and S. Fischer-H{\"u}bner},
   location = {Stockholm University/Royal Institute of Technology, Sweden},
   series = {Report Series 99--008},
   issn = {1101--8526}
}

@inproceedings{HT65,
   title = {Dynamic Metadata for Monitoring Digital Library Management},
   author = {Harold Thimbleby and George Buchanan and G. E. Marsden},
   year = {1999},
   booktitle = {Proceedings Fourth {ACM} Conference on Digital Libraries},
   pages = {219--220},
   location = {Berkeley, California}
}

@article{HT112,
   title = {Meaningful Link Verification for Management and Maintenance of Web Sites},
   author = {Harold Thimbleby and George Buchanan and G. Marsden},
   year = {1999},
   booktitle = {Proceedings 8th. International World Wide Web Conference --- WWW8 Poster Proceedings},
   pages = {170--171},
   location = {Toronto},
   publisher = {Fortec Seminars}
}

The UK Worshipful Company of Information Technologists organised two high-level colloquia to debate ethical and spiritual implication of the new IT & Telecoms Environment in 1997. The colloquia were hosted in the UK House of Lords. This paper summarises the debates of those colloquia, and discusses some of the ethical and cultural issues that arise.

@inproceedings{HT69,
   title = {UK Views on Ethical and Spiritual Implications of {IT}},
   author = {Harold Thimbleby and P. Duquenoy and N. Beale},
   abstract = {The UK Worshipful Company of Information Technologists organised two high-level colloquia to debate ethical and spiritual implication of the new IT {\&} Telecoms Environment in 1997. The colloquia were hosted in the UK House of Lords. This paper summarises the debates of those colloquia, and discusses some of the ethical and cultural issues that arise.},
   year = {1998},
   booktitle = {Proceedings Fourth International Conference on Ethical Issues in Information Technology, Ethicomp'98},
   pages = {734--742}
}

@inproceedings{HT68,
   title = {{HyperAT}: Addressing Usability Issues in Web Authoring},
   author = {Harold Thimbleby and {\main{Y. L. Theng}}},
   year = {1998},
   booktitle = {Proceedings {WebNet}'98, World Conference of the {WWW}, Internet, {\&} Intranet},
   pages = {885--896},
   location = {Orlando, Florida},
   organization = {Association for the Advancement of Computing in Education ({AACE})}
}

@inbook{2020-iee,
   title = {Personal Issues: Personal Boundaries/Global Stage},
   author = {Harold Thimbleby},
   year = {1998},
   booktitle = {2020 Vision: Morality in the Information Society},
   pages = {81--93},
   isbn = {0--85296--702--0},
   publisher = {Institution of Electrical Engineers}
}

@inproceedings{continuous-bcs,
   title = {Towards Continuous Usability Evaluation of Web Documents},
   author = {Harold Thimbleby and {\main{Y. L. Theng}} and G. Marsden},
   year = {1998},
   booktitle = {Proceedings BCS HCI'98, Conference Companion},
   pages = {40--41},
   editor = {J. May and J. Siddiqi and Wilkinson}
}

@inproceedings{HT70,
   title = {Specification-led Design},
   author = {Harold Thimbleby},
   year = {1998},
   booktitle = {Proceedings Living Life to the Full with Personal Technologies},
   pages = {4/1--4/9},
   number = {{IEE} Seminar 98/268}
}

Designer-centred design methods build on the knowledge and skills of the designers to improve user interface design. Unlike users, designers are trained to handle complexity and to make design trade-offs. They are the people centrally in control of the design process. Designer-centred design complements and refocuses user-centred design methods. A particular designer-centred design approach, “Design Aloud” is introduced and justified.

@article{HT7,
   title = {Design Aloud: A Designer-Centred Design {(DCD)} Method},
   author = {Harold Thimbleby},
   abstract = {Designer-centred design methods build on the knowledge and skills of the designers to improve user interface design. Unlike users, designers are trained to handle complexity and to make design trade-offs. They are the people centrally in control of the design process. Designer-centred design complements and refocuses user-centred design methods. A particular designer-centred design approach, ``Design Aloud'' is introduced and justified.},
   year = {1998},
   pages = {45--50},
   journal = {HCI Letters},
   volume = {1},
   number = {1}
}

@article{HT8,
   title = {Addressing Design and Usability Issues in Hypertext and on the Web by re-examining the ``Lost in Hyperspace'' Problem},
   author = {Harold Thimbleby and {\main{Y. L. Theng}}},
   year = {1998},
   pages = {839--855},
   journal = {Journal of Universal Computer Science},
   url = {http://www.iicm.edu/jucs_4_11/addressing_design_and_usability},
   volume = {4},
   number = {11}
}

Also presented at IEE 2020 Vision Meeting on Morality in the Information Society, 11 December 1997. London.

The Internet will apparently solve many problems, but it also creates new ones. We are simply not used to thinking on the scale of the Internet, and our personal views can easily be played out on an unfamiliar global stage, where they may have unintended consequences. Computers, the most logical things we have ever created, are raising serious ethical issues — especially in areas that traditionally have had a low priority in the modern world. We are not used to the global stage.

@article{boundaries-j,
   title = {Personal Boundaries and Global Stage},
   author = {Harold Thimbleby},
   abstract = {Also presented at IEE 2020 Vision Meeting on {\emph{Morality in the Information Society}}, 11 December 1997. London.

The Internet will apparently solve many problems, but it also creates new ones. We are simply not used to thinking on the scale of the Internet, and our personal views can easily be played out on an unfamiliar global stage, where they may have unintended consequences. Computers, the most logical things we have ever created, are raising serious ethical issues --- especially in areas that traditionally have had a low priority in the modern world. We are not used to the global stage.},
   year = {1998},
   journal = {First Monday},
   url = {http://firstmonday.org/htbin/cgiwrap/bin/ojs/index.php/fm/article/view/582/503},
   volume = {3},
   number = {3}
}

A simple language is demonstrated that combines specifications and manuals. This shows first that a user manual can be automatically reconstructed from a logic specification that is effectively identical to the original logic (up to ambiguities in natural language); and secondly, that such an automated process can help detect errors. The process is fast and suitable for use in participatory design.

@article{logtoman1,
   title = {From Logic to Manuals},
   author = {Harold Thimbleby and P. B. Ladkin},
   abstract = {A simple language is demonstrated that combines specifications and manuals. This shows first that a user manual can be automatically reconstructed from a logic specification that is effectively identical to the original logic (up to ambiguities in natural language); and secondly, that such an automated process can help detect errors. The process is fast and suitable for use in participatory design.},
   year = {1997},
   pages = {347--354},
   journal = {Software Engineering Journal},
   volume = {11},
   number = {6}
}

Autostereograms on the Web make a very appealing combination:

• The World Wide Web brings together art, science and technology, both in the medium and in its content. Autostereograms, likewise: based in science, they are art made possible by computer graphics technology.
• The Web is extremely accessible: it makes multimedia available to more people than any other computer-based medium. Autostereograms, similarly, are easily viewed without any special equipment and give true stereoscopic 3D effects.

@inbook{HT173,
   title = {3D Creativity for the Web},
   author = {Harold Thimbleby},
   abstract = {Autostereograms on the Web make a very appealing combination: {\begin{itemize}}{\item} The World Wide Web brings together art, science and technology, both in the medium and in its content. Autostereograms, likewise: based in science, they are art made possible by computer graphics technology. {\item} The Web is extremely accessible: it makes multimedia available to more people than any other computer-based medium. Autostereograms, similarly, are easily viewed without any special equipment and give true stereoscopic 3D effects. {\end{itemize}} This paper discusses stereoscopic 3D effects, and how drawing autostereograms lends itself to the networking constraints and page layout freedom characteristic of the Web. There are wonderful opportunities for making science and art interesting and accessible to wide audiences.},
   year = {1997},
   booktitle = {The Internet in {3D}},
   pages = {41--53},
   isbn = {0--12--227736--8},
   url = {http://cs.swan.ac.uk/~csharold/sirds/index.html},
   editor = {R. Earnshaw and J. Vince},
   publisher = {Academic Press}
}

@article{HT9,
   title = {Calculators True and False},
   author = {Harold Thimbleby},
   year = {1997},
   pages = {214},
   journal = {Engineering Science and Education Journal},
   url = {http://cs.swan.ac.uk/~csharold/calculators/index.html},
   volume = {6},
   number = {5}
}

Existing calculators are unreliable and difficult to use, and they are marketed misleadingly. A new calculator is described that is simple, reliable and very powerful.

@article{HT11,
   title = {A True Calculator},
   author = {Harold Thimbleby},
   abstract = {Existing calculators are unreliable and difficult to use, and they are marketed misleadingly. A new calculator is described that is simple, reliable and very powerful.},
   year = {1997},
   pages = {128--136},
   journal = {Engineering Science and Education Journal},
   url = {http://cs.swan.ac.uk/~csharold/calculators/index.html},
   volume = {6},
   number = {3}
}

We consider some of the range of technological, sociological and infrastructure issues pertinent to the future development of networked interpersonal communication devices and their applications.

@inproceedings{HT73,
   title = {Issues for Networked Interpersonal Communications: The Convergence of Technology {\ldots} With What},
   author = {Harold Thimbleby and M. Addison},
   abstract = {We consider some of the range of technological, sociological and infrastructure issues pertinent to the future development of networked interpersonal communication devices and their applications.},
   year = {1997},
   booktitle = {Proceedings Issues for Networked Interpersonal Communicators},
   pages = {6/1--6/4},
   series = {IEE Colloquium},
   number = {{IEE} Digest 1997/139}
}

@inproceedings{HT115,
   title = {Benjamin Franklin House Web Site},
   author = {Harold Thimbleby and G. E. Marsden and G. Palmer},
   year = {1997},
   booktitle = {WebNet'97},
   location = {Toronto}
}

We argue, with theoretical justification, that authoring hypertext and World Wide Web documents requires tool support if it is to be done well. Tools are essential for good design; without them iterative design and user testing are impractical to follow through because of the prohibitive costs of making even small changes reliably.

Gentler is one such authoring tool. It uses a database of pages and a page layout language, providing reliable design features including hypertext linkage and navigation. With Gentler as a concrete example, we introduce an important principle for design: dual requirements. Features that hypertext document readers find beneficial are beneficial for document authors, and vice versa.

@article{gentler-ijhcs,
   title = {Gentler: A Tool for Systematic Web Authoring},
   author = {Harold Thimbleby},
   abstract = {We argue, with theoretical justification, that authoring hypertext and World Wide Web documents requires tool support if it is to be done well. Tools are essential for good design; without them iterative design and user testing are impractical to follow through because of the prohibitive costs of making even small changes reliably. 

Gentler is one such authoring tool. It uses a database of pages and a page layout language, providing reliable design features including hypertext linkage and navigation. With Gentler as a concrete example, we introduce an important principle for design: {\emph{dual requirements}}. Features that hypertext document readers find beneficial are beneficial for document authors, and {\emph{vice versa}}.},
   year = {1997},
   pages = {139--168},
   journal = {International Journal of Human-Computer Studies},
   volume = {47},
   number = {1}
}

A simple and general scheme is described that permits multiple authors to collaborate on certain sorts of hypermedia document. The scheme separates content, page design, and site structure. Each author can work in a small space, and therefore have higher quality control over their product. By allowing multiple authors, the workload is divided.

A prototype system has been implemented (in Java) and shows the scheme is feasible, and that it scales up to arbitrary size sites. The prototype suggests many profitable developments.

@inproceedings{HT71,
   title = {Distributed Web Authoring},
   author = {Harold Thimbleby},
   abstract = {A simple and general scheme is described that permits multiple authors to collaborate on certain sorts of hypermedia document. The scheme separates content, page design, and site structure. Each author can work in a small space, and therefore have higher quality control over their product. By allowing multiple authors, the workload is divided.

A prototype system has been implemented (in Java) and shows the scheme is feasible, and that it scales up to arbitrary size sites. The prototype suggests many profitable developments.},
   year = {1997},
   booktitle = {Proceedings {WebNet'97}, World Conference of the {WWW}, Internet, {\&} Intranet},
   pages = {1056--1083},
   isbn = {1--880094--27--4},
   editor = {S. Lobodzinski and I. Tomek},
   location = {Toronto, Canada},
   publisher = {Association for the Advancement of Computing in Education ({AACE})}
}

We demonstrate a simple language that combines specifications and manuals. This shows: first, that a user manual can be automatically reconstructed from a logic specification that is effectively identical to the original logic (up to ambiguities in natural language); second, that such an automated process can help detect errors. The process is fast, and suitable for use in participatory design.

See also the HTML source code for this paper (i.e., the paper written in the language the paper is about, and which generated the published paper).

@article{logtoman2,
   title = {From Logic to Manuals Again},
   author = {Harold Thimbleby and P. B. Ladkin},
   abstract = {We demonstrate a simple language that combines specifications and manuals. This shows: first, that a user manual can be automatically reconstructed from a logic specification that is effectively identical to the original logic (up to ambiguities in natural language); second, that such an automated process can help detect errors. The process is fast, and suitable for use in participatory design. 

See also the HTML source code for this paper (i.e., the paper written in the language the paper is about, and which generated the published paper).},
   year = {1997},
   pages = {185--192},
   journal = {IEE Proceedings Software Engineering},
   volume = {144},
   number = {3}
}

We argue that button-controlled devices can be made better to improve their usability, and that there are routine ways to do so that can be effectively employed in the early stages of the design process.

By way of example, we examine the design of a 1993/4 domestic phone/fax/answerphone machine, and show that alternative designs have quantitative advantages over the original. We point to many strange — obscure, undocumented, non-functional — features, and raise questions about the process that led to the design, and what role either human factors or computer science played in it.

@article{HT10,
   title = {Design for a Fax},
   author = {Harold Thimbleby},
   abstract = {We argue that button-controlled devices can be made better to improve their usability, and that there are routine ways to do so that can be effectively employed in the early stages of the design process. 

By way of example, we examine the design of a 1993/4 domestic phone/fax/answerphone machine, and show that alternative designs have quantitative advantages over the original. We point to many strange --- obscure, undocumented, non-functional --- features, and raise questions about the process that led to the design, and what role either human factors or computer science played in it.},
   year = {1997},
   pages = {101--117},
   journal = {Personal Technologies},
   volume = {1},
   number = {2}
}

@inproceedings{hyperat-bcs,
   title = {{HyperAT}: {HCI} and Web Authoring},
   author = {Harold Thimbleby and {\main{Y. L. Theng}} and C. Rigny and M. Jones},
   year = {1997},
   booktitle = {Proceedings {BCS} {HCI'97}, People and Computers},
   pages = {359--378},
   isbn = {3--540--76172--1},
   volume = {XII},
   editor = {H. Thimbleby and B. O'Conaill and P. J. Thomas},
   publisher = {Springer Verlag},
   location = {Bristol, England}
}

@inproceedings{HT72,
   title = {Benjamin Franklin House: An Illustration of a Site Management and Visual Design Tool for Complex, Multi-authored Web Sites},
   author = {Harold Thimbleby and G. E. Marsden and G. J. Palmer},
   year = {1997},
   booktitle = {Proceedings WebNet'97, World Conference of the {WWW}, Internet, {\&} Intranet},
   pages = {688},
   isbn = {1--880094--27--4},
   editor = {S. Lobodzinski and I. Tomek},
   location = {Toronto, Canada},
   publisher = {Association for the Advancement of Computing in Education ({AACE})}
}

@inproceedings{HT114,
   title = {Is `Lost in Hyperspace' Lost in Controversy?},
   author = {Harold Thimbleby and {\main{Y.~L. Theng}}},
   year = {1997},
   booktitle = {Hypertext'97},
   location = {Southampton}
}

We discuss and show correct an algorithm that constructs autostereograms. The concern is to develop a correct algorithm that may be implemented in a language such as C or Pascal.

@article{stereo-spae,
   title = {An Efficient Equivalence Class Algorithm with Applications to Autostereograms},
   author = {Harold Thimbleby},
   abstract = {We discuss and show correct an algorithm that constructs autostereograms. The concern is to develop a correct algorithm that may be implemented in a language such as C or Pascal.},
   year = {1996},
   pages = {309--325},
   journal = {Software --- Practice {\&} Experience},
   url = {http://cs.swan.ac.uk/~csharold/sirds/index.html},
   volume = {26},
   number = {3}
}

Manuals and interactive help are tedious to provide, difficult to maintain, and difficult to ensure correct, even for simple systems. The result is a loss in product quality, felt particularly by users and designers committed to long-term product development.

This paper shows that it is possible to systematically put a system specification and its documentation into exact correspondence. It follows that much previously manual work can be done automatically — and with considerable advantages, including guaranteed correctness and completeness, as well as supporting powerful new features such as intelligent adaptive assistance. This paper shows how interactive assistance can be provided to answer “how to?”, “why not?” and other questions.

@article{adapt-iwc,
   title = {Intelligent Adaptive Assistance and Its Automatic Generation},
   author = {Harold Thimbleby and M. A. Addison},
   abstract = {Manuals and interactive help are tedious to provide, difficult to maintain, and difficult to ensure correct, even for simple systems. The result is a loss in product quality, felt particularly by users and designers committed to long-term product development. 

This paper shows that it is possible to systematically put a system specification and its documentation into exact correspondence. It follows that much previously {\emph{manual\/}} work can be done automatically --- and with considerable advantages, including guaranteed correctness and completeness, as well as supporting powerful new features such as intelligent adaptive assistance. This paper shows how interactive assistance can be provided to answer ``how to?'', ``why not?'' and other questions.},
   year = {1996},
   pages = {51--68},
   journal = {Interacting with Computers},
   volume = {8},
   number = {1}
}

@inproceedings{cogmod-bcs,
   title = {Cognitive User Models as Design Aids},
   author = {Harold Thimbleby and {\main{C. Rigny}} and Y. L. Theng},
   year = {1996},
   booktitle = {Adjunct Proceedings {BCS} {HCI'96}},
   pages = {139--144},
   isbn = {1--85924--119--0},
   editor = {H. Thimbleby and Ann Blandford}
}

@inproceedings{cogtask-asia,
   title = {Cognitive Task Graphs and Executable User Models for Better Hypertext},
   author = {Harold Thimbleby and Y. L. Theng and {\main{C. Rigny}} and M. Jones},
   year = {1996},
   booktitle = {Proceedings First Asia Pacific Conference on Human Computer Interaction --- APCHI},
   pages = {421--433},
   isbn = {9971--88--495--X},
   editor = {L. K. Yong and L. Herman and Y. K. Leung and J. Moyes},
   location = {Singapore}
}

@inproceedings{idc-asia,
   title = {The Interaction Design Centre},
   author = {Harold Thimbleby and Ann Blandford},
   year = {1996},
   booktitle = {Proceedings First Asia Pacific Conference on Human Computer Interaction --- APCHI},
   pages = {421--433},
   editor = {L. K. Yong and L. Herman and Y. K. Leung and J. Moyes},
   location = {Singapore}
}

@inproceedings{concept-bcs,
   title = {Improved Conceptual Design for Better Hypertext},
   author = {Harold Thimbleby and Y. L. Theng and C. Rigny and M. Jones},
   year = {1996},
   booktitle = {Adjunct Proceedings {BCS} {HCI}'96},
   pages = {181--188},
   isbn = {1--85924--119--0},
   editor = {H. Thimbleby and Ann Blandford}
}

@inproceedings{cumdes-bcs,
   title = {{CUM-DesTool}: Applying Executable User Models for Designing Interactive Systems},
   author = {Harold Thimbleby and {\main{C. Rigny}}},
   year = {1996},
   booktitle = {Adjunct Proceedings {BCS} {HCI'96}},
   pages = {145--149},
   isbn = {1--85924--119--0},
   editor = {H. Thimbleby and Ann Blandford}
}

@inproceedings{hyper-asia,
   title = {`Lost in Hyperspace': Psychological Problem or Bad Design},
   author = {Harold Thimbleby and {\main{Y. L. Theng}} and M. Jones},
   year = {1996},
   booktitle = {Proceedings First Asia Pacific Conference on Human Computer Interaction --- APCHI},
   pages = {387--396},
   isbn = {9971--88--495--X},
   editor = {L. K. Yong and L. Herman and Y. K. Leung and J. Moyes},
   location = {Singapore}
}

User manuals are usually written by technical authors after the design of the device has been committed for production. If the manual’s review leads to insight into the design, it is too late. Meanwhile, if the design is modified, the manual may be inaccurate. This paper describes an example language for creating accurate and complete manuals from formal specifications. We show how it can be used to improve part of the Flight Crew Operating Manual for the Airbus A320 fly-by-wire airplane. The technique is easy to implement, can be generalised to other domains, and contributes to concurrent engineering practice — increasing common ground between engineers, users and HCI practitioners.

@inproceedings{manuals-chi,
   title = {Creating User Manuals for Use in Collaborative Design},
   author = {Harold Thimbleby},
   abstract = {User manuals are usually written by technical authors after the design of the device has been committed for production. If the manual's review leads to insight into the design, it is too late. Meanwhile, if the design is modified, the manual may be inaccurate. This paper describes an example language for creating accurate and complete manuals from formal specifications. We show how it can be used to improve part of the Flight Crew Operating Manual for the Airbus A320 fly-by-wire airplane. The technique is easy to implement, can be generalised to other domains, and contributes to concurrent engineering practice --- increasing common ground between engineers, users and HCI practitioners.},
   year = {1996},
   booktitle = {Proceedings ACM Conference on Computer-Human Interaction --- CHI'96},
   pages = {279--280},
   editor = {M. Tauber},
   location = {Vancouver, Canada}
}

@inproceedings{rigny-asia,
   title = {Cognitive User Models as Design Aids},
   author = {Harold Thimbleby and Y. L. Theng and {\main{C. Rigny}}},
   year = {1996},
   booktitle = {Proceedings First Asia Pacific Conference on Human Computer Interaction --- APCHI},
   pages = {387--396},
   isbn = {9971--88--495--X},
   editor = {L. K. Yong and L. Herman and Y. K. Leung and J. Moyes},
   location = {Singapore}
}

@inbook{HT174,
   title = {Observations on Practically Perfect CSCW},
   author = {Harold Thimbleby and D. J. Pullinger},
   year = {1996},
   booktitle = {Remote Cooperation. CSCW Issues for Mobile and Teleworkers},
   pages = {69--86},
   isbn = {3--540--76035--0},
   editor = {A. J. Dix and Russell Beale},
   publisher = {Springer Verlag}
}

Quality program design has received considerable attention from the software engineering community. Quality user manual design has received considerable attention from the human computer interaction community. Yet manuals and systems are often independently conceived, and thus do not well complement each other. This paper shows one method of easily obtaining correct and complete user manuals guaranteed to correspond with the system they document. The method has considerable merit for improving interactive systems design.

@inproceedings{explan-bcs,
   title = {A Proper Explanation When You Need One},
   author = {Harold Thimbleby and P. B. Ladkin},
   abstract = {Quality program design has received considerable attention from the software engineering community. Quality user manual design has received considerable attention from the human computer interaction community. Yet manuals and systems are often independently conceived, and thus do not well complement each other. This paper shows one method of easily obtaining correct and complete user manuals guaranteed to correspond with the system they document. The method has considerable merit for improving interactive systems design.},
   year = {1995},
   pages = {107--118},
   isbn = {0--521--56729--7},
   journal = {Proceedings British Computer Society Conference HCI'95, People and Computers},
   volume = {X},
   editor = {M. A. R. Kirby and A. J. Dix and J. E. Finlay},
   location = {Huddersfield},
   publisher = {Cambridge University Press}
}

@inproceedings{HT76,
   title = {Hypermedia Manuals for Interactive Systems},
   author = {Harold Thimbleby and M. A. Addison},
   year = {1995},
   booktitle = {Proceedings The Authoring and Application of Hypermedia-based User-Interfaces},
   pages = {5/1--5/4},
   series = {IEE Colloquium},
   number = {IEE Digest 1995/202}
}

@article{HT12,
   title = {An Example of Distribution-Free Testing},
   author = {Harold Thimbleby},
   year = {1995},
   pages = {62--65},
   journal = {Mathematica Journal},
   volume = {5},
   number = {2}
}

@inproceedings{HT75,
   title = {Designer Tools for Hypertext Authoring},
   author = {Harold Thimbleby and Y. L. Theng and M. Jones},
   year = {1995},
   booktitle = {Proceedings The Authoring and Application of Hypermedia-based User-Interfaces},
   pages = {4/1--4/4},
   series = {IEE Colloquium},
   number = {IEE Digest 1995/202}
}

@inproceedings{notlost-bcs,
   title = {Authoring Consistent Hypermedia Without Getting Lost},
   author = {Harold Thimbleby},
   year = {1995},
   booktitle = {Proceedings British Computer Society Conference on People and Computers, {HCI}'95, Adjunct Proceedings},
   pages = {118--124},
   editor = {G. Allen and J. Wilkinson and P. Wright}
}

We have built some simple, but useful, cooperative Artificial Life agents. Based on this experience and by contrasting our work with computer viruses, we argue that Artificial Life (the simulation of life including evolution) can only remain reliably and indefinitely cooperative if it adheres to explicitly-specified social conventions. Breaking or neglecting these conventions results in systems that are worse than useless; in fact, malicious with respect to human social values.

@article{HT13,
   title = {Concepts of Cooperation in Artificial Life},
   author = {Harold Thimbleby and D. J. Pullinger and I. H. Witten},
   abstract = {We have built some simple, but useful, cooperative Artificial Life agents. Based on this experience and by contrasting our work with computer viruses, we argue that Artificial Life (the simulation of life including evolution) can only remain {\emph{reliably\/}} and indefinitely cooperative if it adheres to explicitly-specified social conventions. Breaking or neglecting these conventions results in systems that are worse than useless; in fact, malicious with respect to human social values.},
   year = {1995},
   pages = {1166--1171},
   journal = {IEEE Transactions on Systems, Man {\&} Cybernetics},
   volume = {25},
   number = {7}
}

@inproceedings{hyperdoc-bcs,
   title = {HyperDoc: An Interactive System Development Tool},
   author = {Harold Thimbleby and M. A. Addison},
   year = {1995},
   booktitle = {Proceedings British Computer Society Conference HCI'95, People and Computers},
   pages = {95--106},
   isbn = {0--521--56729--7},
   volume = {X},
   location = {Huddersfield},
   editor = {M. A. R. Kirby and A. J. Dix and J. E. Finlay},
   publisher = {Cambridge University Press}
}

Conventional calculators are badly designed: they suffer from bad computer science — they are unnecessarily difficult to use and bug ridden. I describe a solution, avoiding the problems caused by conventional calculators that is more powerful and arguably much easier to use. The solution has been implemented, and design issues are discussed. This paper shows an interactive system that is declarative, with the advantages of clarity and power that entails. It frees people from working out how a calculation should be expressed to concentrating on what they want solved. An important contribution is to demonstrate the very serious problems users face when using conventional calculators, and hence what a freedom a declarative design brings.

@article{newcalc-cj,
   title = {A New Calculator and Why it is Necessary},
   author = {Harold Thimbleby},
   abstract = {Conventional calculators are badly designed: they suffer from bad computer science --- they are unnecessarily difficult to use and bug ridden. I describe a solution, avoiding the problems caused by conventional calculators that is more powerful and arguably much easier to use. The solution has been implemented, and design issues are discussed. This paper shows an interactive system that is declarative, with the advantages of clarity and power that entails. It frees people from working out how a calculation should be expressed to concentrating on what they want solved. An important contribution is to demonstrate the very serious problems users face when using conventional calculators, and hence what a freedom a declarative design brings.},
   year = {1995},
   pages = {418--433},
   journal = {Computer Journal},
   url = {http://cs.swan.ac.uk/~csharold/calculators/index.html},
   volume = {38},
   doi = {10.1093/comjnl/38.6.418},
   number = {6}
}

@inproceedings{HT77,
   title = {``Users as Computers'': An Approach to VR Design and Conceptual Evaluation},
   author = {Harold Thimbleby},
   year = {1995},
   booktitle = {Proceedings Conference on Interface to Real and Virtual Worlds},
   pages = {305--313},
   volume = {IV}
}

It was pointed out in the Preface that the term handicap applies to the effects a person’s limitations have on their ability to function in their environment. This chapter explores that concept in a very important direction: it advances the proposition that the average human-computer interface is so badly designed that anyone who uses it is handicapped by it. Moreover, it suggests a practical way to start to respect the user, based in the theory of computer science. It should therefore appeal to the computer scientists and programmers who design interactive systems.

@inbook{HT175,
   title = {Treat People Like Computers? {Designing} Usable Systems for Special People},
   author = {Harold Thimbleby},
   abstract = {It was pointed out in the Preface that the term handicap applies to the effects a person's limitations have on their ability to function in their environment. This chapter explores that concept in a very important direction: it advances the proposition that the average human-computer interface is so badly designed that anyone who uses it is handicapped by it. Moreover, it suggests a practical way to start to respect the user, based in the theory of computer science. It should therefore appeal to the computer scientists and programmers who design interactive systems.},
   year = {1995},
   booktitle = {Extraordinary People and Human-Computer Interaction},
   pages = {283--295},
   isbn = {0--521--43413--0},
   editor = {A. Edwards},
   publisher = {Cambridge University Press}
}

A personal digital assistant (PDA) is not interesting — it would be nothing more than a glamorous organiser — while it remains merely personal. What makes a PDA interesting and worthwhile is its ability to extend the small world of the personal user to the wider world, involving many users distributed over space and time. If it was not for this widening of horizons, a PDA would be both personal and private: whether someone had a PDA would not be known to another person, and therefore it could not make a significant impact on the owner’s operation in the world.

@inbook{HT176,
   title = {Usability, Communication and Security and Personal Digital Assistants ({PDAs})},
   author = {Harold Thimbleby},
   abstract = {A personal digital assistant (PDA) is not interesting --- it would be nothing more than a glamorous organiser --- while it remains merely personal. What makes a PDA interesting and worthwhile is its ability to extend the small world of the personal user to the wider world, involving many users distributed over space and time. If it was not for this widening of horizons, a PDA would be both personal and private: whether someone had a PDA would not be known to another person, and therefore it could not make a significant impact on the owner's operation in the world.},
   year = {1995},
   booktitle = {Personal Information Management},
   pages = {31--43},
   isbn = {0--7487--2327--7},
   editor = {P. J. Thomas},
   publisher = {Stanley Thornes}
}

@inproceedings{HT74,
   title = {Reducing Information Overload: A Comparative Study Of Hypertext Systems},
   author = {Harold Thimbleby and {\main{Y. L. Theng}} and M. Jones},
   year = {1995},
   booktitle = {Proceedings Information Overload},
   pages = {6/1--6/5},
   series = {IEE Colloquium},
   number = {IEE Digest 1995/223}
}

The complementary paradigms of text compression and image compression suggest that there may be potential for applying methods developed for one domain to the other. In image coding, lossy techniques yield compression factors that are vastly superior to those of the best lossless schemes, and we show that this is also the case for text. This paper investigates the resulting tradeoff between subjective quality of the transmission and its compression factor. Two different methods are described, which can be combined into an extremely effective technique that provides far better compression than the present state of the art and yet preserves a reasonable degree of perceived match between the original and received text. The major challenge for lossy text compression is the quantitative evaluation of the quality of this match.

@article{april-cj,
   title = {Semantic and Generative Models for Lossy Text Compression},
   author = {Harold Thimbleby and I. H. Witten and T. C. Bell and A. Moffat and C. G. Nevill-Manning and T. C. Smith},
   abstract = {The complementary paradigms of text compression and image compression suggest that there may be potential for applying methods developed for one domain to the other. In image coding, lossy techniques yield compression factors that are vastly superior to those of the best lossless schemes, and we show that this is also the case for text. This paper investigates the resulting tradeoff between subjective quality of the transmission and its compression factor. Two different methods are described, which can be combined into an extremely effective technique that provides far better compression than the present state of the art and yet preserves a reasonable degree of perceived match between the original and received text. The major challenge for lossy text compression is the quantitative evaluation of the quality of this match.},
   year = {1994},
   pages = {83--87},
   journal = {Computer Journal},
   volume = {37},
   number = {2}
}

Usability is empirical, and often highly context-specific, but it would be useful for designers to have general estimates of usability from interactive system specifications alone. We discuss how this problem may be approached, and we give examples. We also discuss the justification for the approach, since it is unusual to measure usability without involving users. The explicit mathematical content of this paper has been deliberately kept to a minimum.

@article{HT19,
   title = {Formulating Usability},
   author = {Harold Thimbleby},
   abstract = {Usability is empirical, and often highly context-specific, but it would be useful for designers to have general estimates of usability from interactive system specifications alone. We discuss how this problem may be approached, and we give examples. We also discuss the justification for the approach, since it is unusual to measure usability without involving users. The explicit mathematical content of this paper has been deliberately kept to a minimum.},
   year = {1994},
   pages = {59--64},
   journal = {ACM SIGCHI Bulletin},
   volume = {26},
   number = {2}
}

@inproceedings{lang-bcs,
   title = {Designing the Interface Programming Language for the End User},
   author = {Harold Thimbleby and {\main{G. Marsden}}},
   year = {1994},
   booktitle = {BCS Conference on People and Computers, {HCI}'94}
}

Interactive computer systems can support their users in problem solving, both in performing their work tasks and in using the systems themselves. Not only is direct support for heuristics beneficial, but to do so modifies the form of computer support provided. This paper defines and explores the use of problem solving heuristics in user interface design.

A demonstration hypertext system, Hyperwriter, was developed as the outcome of considering general problem-solving heuristics as goals of interactive systems design. Whereas hypertext joins and relates ideas, Hyperwriter additionally, and as a direct outcome of the design approach, has ways of separating, ordering and polishing ideas. As an application for creative writing, Hyperwriter supports effective thinking over a period of time. (This paper was drafted, organised and re-organised using the system itself.) Some issues arising in implementing Hyperwriter are also discussed.

@article{HT15,
   title = {Designing Interfaces for Problem Solving},
   author = {Harold Thimbleby},
   abstract = {Interactive computer systems can support their users in problem solving, both in performing their work tasks and in using the systems themselves. Not only is direct support for heuristics beneficial, but to do so modifies the form of computer support provided. This paper defines and explores the use of problem solving heuristics in user interface design. 

A demonstration hypertext system, Hyperwriter, was developed as the outcome of considering general problem-solving heuristics as goals of interactive systems design. Whereas hypertext joins and relates ideas, Hyperwriter additionally, and as a direct outcome of the design approach, has ways of separating, ordering and polishing ideas. As an application for creative writing, Hyperwriter supports effective thinking over a period of time. (This paper was drafted, organised and re-organised using the system itself.) Some issues arising in implementing Hyperwriter are also discussed.},
   year = {1994},
   note = {with Application to Hypertext and Creative Writing},
   pages = {29--44},
   journal = {AI {\&} Society},
   volume = {8}
}

We discuss a procedure proposed by Voas, Payne & Cohen for detecting the existence of software corruption in real time. In particular, we discuss problems posed by the concurrent execution of programs. In the cases where the proposed method may work, corruption is unlikely to be a problem; and where corruption by viruses and Trojans are a problem, major problems with the method remain.

@article{HT14,
   title = {Comments on A Paper by Voas, Payne {\&} Cohen: ``A Model for Detecting the Existence of Software Corruption in Real Time''},
   author = {Harold Thimbleby and P. Ladkin},
   abstract = {We discuss a procedure proposed by Voas, Payne {\&} Cohen for detecting the existence of software corruption in real time. In particular, we discuss problems posed by the concurrent execution of programs. In the cases where the proposed method may work, corruption is unlikely to be a problem; and where corruption by viruses and Trojans are a problem, major problems with the method remain.},
   year = {1994},
   pages = {527--531},
   journal = {Computers {\&} Security},
   volume = {13},
   number = {6}
}

This paper describes how to generate a single image which, when viewed in the appropriate way, appears to the brain as a 3D scene. The image is a stereogram composed of seemingly random dots. A new, simple and symmetric algorithm for generating such images from a solid model is given, along with the design parameters and their influence on the display. The algorithm improves on previously-described ones in several ways: it is symmetric and hence free from directional (right-to-left or left-to-right) bias, it corrects a slight distortion in the rendering of depth, it removes hidden parts of surfaces, and it also eliminates a type of artifact that we call an “echo.”

Random dot stereograms have one remaining problem: difficulty of initial viewing. If a computer screen rather than paper is used for output, the problem can be ameliorated by shimmering, or time-multiplexing of pixel values. We also describe a simple computational technique for determining what is present in a stereogram so that, if viewing is difficult, one can ascertain what to look for.

@article{HT16,
   title = {Displaying 3D Images: Algorithms for Single-Image Random-Dot Stereograms},
   author = {Harold Thimbleby and I. H. Witten and S. Inglis},
   abstract = {This paper describes how to generate a single image which, when viewed in the appropriate way, appears to the brain as a 3D scene. The image is a stereogram composed of seemingly random dots. A new, simple and symmetric algorithm for generating such images from a solid model is given, along with the design parameters and their influence on the display. The algorithm improves on previously-described ones in several ways: it is symmetric and hence free from directional (right-to-left or left-to-right) bias, it corrects a slight distortion in the rendering of depth, it removes hidden parts of surfaces, and it also eliminates a type of artifact that we call an ``echo.''

Random dot stereograms have one remaining problem: difficulty of initial viewing. If a computer screen rather than paper is used for output, the problem can be ameliorated by shimmering, or time-multiplexing of pixel values. We also describe a simple computational technique for determining what is present in a stereogram so that, if viewing is difficult, one can ascertain what to look for.},
   year = {1994},
   pages = {38--48},
   journal = {IEEE Computer},
   url = {http://cs.swan.ac.uk/~csharold/sirds/index.html},
   volume = {27},
   number = {10}
}

Conventional protection methods against software piracy and computer viruses are limited in their effectiveness and timeliness. A cryptographic method, introduced in this paper, can stop the spread of viruses of all kinds, stop software piracy, and can be ideal for organisational purposes. Computer use within an organisation is completely unaffected.

@article{HT18,
   title = {An Organisational Solution to Piracy and Viruses},
   author = {Harold Thimbleby},
   abstract = {Conventional protection methods against software piracy and computer viruses are limited in their effectiveness and timeliness. A cryptographic method, introduced in this paper, can stop the spread of viruses of all kinds, stop software piracy, and can be ideal for organisational purposes. Computer use within an organisation is completely unaffected.},
   year = {1994},
   pages = {207--215},
   journal = {Journal of Systems and Software},
   volume = {25},
   number = {2}
}

@article{hubris1,
   title = {Technological Hubris},
   author = {Harold Thimbleby},
   year = {1994},
   pages = {229--234},
   journal = {Computers {\&} Digital Techniques},
   volume = {5},
   number = {5}
}

Most user interfaces are constructed by programs, so there is no direct relationship between the program, its structure and the user interface it implements. For example, graphics drawn on a screen need have no correspondence with regions of the screen sensitive to the user’s input. View binding is introduced as a binding scheme (related to static or lexical binding schemes) whereby the user’s browsing the user interface also manipulates the program’s environment in a particular way. The result is a direct relation between user interface and program, with many advantages.

Like particular binding schemes in programming languages, view binding is not a solution to every programmer’s or user’s wishes, yet it provides a useful discipline that can help simplify user interfaces and their programs. In particular, it is very suitable for user enhanceable systems.

No system currently available is implemented with a strict view binding scheme, but this paper exhibits suggestive examples taken from several well-known programming languages and interactive systems.

@article{HT17,
   title = {View Binding and User Enhanceable Systems},
   author = {Harold Thimbleby},
   abstract = {Most user interfaces are constructed by programs, so there is no direct relationship between the program, its structure and the user interface it implements. For example, graphics drawn on a screen need have no correspondence with regions of the screen sensitive to the user's input. View binding is introduced as a binding scheme (related to static or lexical binding schemes) whereby the user's browsing the user interface also manipulates the program's environment in a particular way. The result is a direct relation between user interface and program, with many advantages. 

Like particular binding schemes in programming languages, view binding is not a solution to every programmer's or user's wishes, yet it provides a useful discipline that can help simplify user interfaces and their programs. In particular, it is very suitable for user enhanceable systems.

No system currently available is implemented with a strict view binding scheme, but this paper exhibits suggestive examples taken from several well-known programming languages and interactive systems.},
   year = {1994},
   pages = {337--349},
   journal = {The Visual Computer: An International Journal of Computer Graphics},
   volume = {10},
   number = {6}
}

A user manual may provide instructions that, if the user follows them, achieve any of certain objectives as determined by the manual designers. A manual may therefore be viewed rather like a computer program, as pre-planned instructions. Accordingly, software engineering and its methods may be applied mutatis mutandis to the manual and its design process.

We consider structured programming methods, and show that some difficulties with user interfaces may be attributed to manuals being “unstructured.” Since there are many programming metrics, and very many styles of manuals for user interfaces, this paper is concerned with justifying the approach and showing how insightful it is.

@inproceedings{structured-bcs,
   title = {Manuals as Structured Programs},
   author = {Harold Thimbleby and M. A. Addison},
   abstract = {A user manual may provide instructions that, if the user follows them, achieve any of certain objectives as determined by the manual designers. A manual may therefore be viewed rather like a computer program, as pre-planned instructions. Accordingly, software engineering and its methods may be applied {\emph{mutatis mutandis\/}} to the manual and its design process. 

We consider structured programming methods, and show that some difficulties with user interfaces may be attributed to manuals being ``unstructured.'' Since there are many programming metrics, and very many styles of manuals for user interfaces, this paper is concerned with justifying the approach and showing how insightful it is.},
   year = {1994},
   booktitle = {Proceedings British Computer Society Conference HCI'94, People and Computers},
   pages = {67--79},
   isbn = {0--521--48557--6},
   volume = {IX},
   editor = {G. Cockton and S. W. Draper and G. R. S. Weir},
   publisher = {Cambridge University Press}
}

Computerisation is the technological imperative, yet it often results in deeper social malaise than the simpler methods replaced; the alienations, even inefficiencies, that they represent become more rigidly entrenched. All this is well known and widely debated. It is systemic and seems intractable. This article discusses a similar problem at the level of user interface design, a much smaller domain and one where there can be more hope.

@article{solution-bit,
   title = {Solutioneering in User Interface Design},
   author = {Harold Thimbleby and Will Thimbleby},
   abstract = {Computerisation is the technological imperative, yet it often results in deeper social malaise than the simpler methods replaced; the alienations, even inefficiencies, that they represent become more rigidly entrenched. All this is well known and widely debated. It is systemic and seems intractable. This article discusses a similar problem at the level of user interface design, a much smaller domain and one where there can be more hope.},
   year = {1993},
   pages = {190--193},
   journal = {Behaviour and Information Technology},
   volume = {12},
   number = {3}
}

@article{parkinson1,
   title = {Computerised Parkinson's Law},
   author = {Harold Thimbleby},
   year = {1993},
   pages = {197--198},
   journal = {Computing {\&} Control Engineering Journal},
   volume = {4},
   number = {5}
}

@article{HT20,
   title = {A Personal View: Software Mechanics},
   author = {Harold Thimbleby},
   year = {1993},
   pages = {110--111},
   journal = {Software Engineering Journal},
   volume = {8},
   number = {3}
}

@article{HT22,
   title = {GenaillesRods.m package},
   author = {Harold Thimbleby},
   year = {1993},
   note = {Converted to Mathematica 8},
   journal = {Mathematica Journal Electronic Supplement},
   url = {http://www.mathematica-journal.com/issue/v3i2/},
   volume = {3},
   number = {2}
}

Henri Genaille’s Rods are a nineteenth-century device for doing multiplication, similar to, but easier to use than, the more familiar Napier’s Bones. Genaille’s Rods are visually attractive and useful in teaching. This article shows how to use Mathematica to draw the required diagrams, which can then be cut out with scissors and passed to wooden rods to make an accurate set of rods.

@article{HT21,
   title = {Genaille's Rods},
   author = {Harold Thimbleby},
   abstract = {Henri Genaille's Rods are a nineteenth-century device for doing multiplication, similar to, but easier to use than, the more familiar Napier's Bones. Genaille's Rods are visually attractive and useful in teaching. This article shows how to use Mathematica to draw the required diagrams, which can then be cut out with scissors and passed to wooden rods to make an accurate set of rods.},
   year = {1993},
   pages = {60--62},
   journal = {Mathematica Journal},
   url = {http://library.wolfram.com/infocenter/Articles/3146/},
   volume = {3},
   number = {2}
}

@inproceedings{HT78,
   title = {Hypertext as a Combined System and Manual},
   author = {Harold Thimbleby},
   year = {1993},
   booktitle = {Proceedings Workshop on Issues in Computer Support for Documentation and Manuals},
   pages = {8/1--8/5},
   series = {IEE Colloquium},
   number = {IEE Digest 1993/169}
}

This chapter takes a formal approach to the design of a class of user interfaces, and shows that some “psychological” design guidelines can be approached without assumptions of human psychology. We suggest an operational approach to assessing user interfaces, with a theoretical foundation in systems theory. Although more work in applying formal methods to HCI is required, we provide arguments for its importance, not least because of the intrinsic unreliability of empirical methods in the face of the complexity of even the simplest of interactive systems. We also argue that much of this complexity is in any case spurious and exacerbates user interface problems, indeed, drives the debate about quality in user interfaces away from fundamental issues towards cosmetic concealing of design faults.

A reader of this chapter commented that, “I would not argue that these problems aren’t important, but they seem minor compared to the real task of designing a system that suggests and supports appropriate, task-relevant actions.” This is based on a misconception: the real task of design includes more than just making a system suggest and support task-relevant actions (and so forth). It must do so reliably, completely, and consistently (to chosen criteria): in short, it must be trustworthy. Without a formal basis — which is what we argue for — interactive systems merely give the temporary semblance of being easy to use. The thorough study of even a simple interactive system is beyond either users or conventional empirical design methods: formal analysis is essential.

@inbook{HT179,
   title = {User Modelling as Machine Identification: New Design Methods for {HCI}},
   author = {Harold Thimbleby and I. H. Witten},
   abstract = {This chapter takes a formal approach to the design of a class of user interfaces, and shows that some ``psychological'' design guidelines can be approached without assumptions of human psychology. We suggest an operational approach to assessing user interfaces, with a theoretical foundation in systems theory. Although more work in applying formal methods to HCI is required, we provide arguments for its importance, not least because of the intrinsic unreliability of empirical methods in the face of the complexity of even the simplest of interactive systems. We also argue that much of this complexity is in any case spurious and exacerbates user interface problems, indeed, drives the debate about quality in user interfaces away from fundamental issues towards cosmetic concealing of design faults.

A reader of this chapter commented that, ``I would not argue that these problems aren't important, but they seem minor compared to the real task of designing a system that suggests and supports appropriate, task-relevant actions.'' This is based on a misconception: the real task of design includes more than just making a system suggest and support task-relevant actions (and so forth). It must do so reliably, completely, and consistently (to chosen criteria): in short, it must be trustworthy. Without a formal basis --- which is what we argue for --- interactive systems merely give the temporary semblance of being easy to use. The thorough study of even a simple interactive system is beyond either users or conventional empirical design methods: formal analysis is essential.},
   year = {1993},
   booktitle = {Advances in Human Computer Interaction},
   pages = {58--86},
   isbn = {0--89391--934--9},
   volume = {IV},
   editor = {D. Hix and H. R. Hartson},
   publisher = {Ablex}
}

Technical systems are so powerful that there is a temptation to try to provide “perfect” support for any cooperative work practice. Some CSCW problems result from designs motivated by optimising technical criteria. A very high bandwidth network, for instance, can support a wide variety of work patterns; the consequent focus of solving the salient technical problems gives the impression that CSCW is a merely social concern. We suggest a class of CSCW system property, observational properties, which are required by users. This motivates a description of an appropriate technology to support such properties. Observational properties tend to be easier to support, so that systems may be more robust or able to handle degradation more gracefully. When an observer cannot distinguish a CSCW system from a perfect system, we say the system is practically perfect. Practically perfect CSCW can be achieved either by perfect technology or, more appropriately, by judicious design of the CSCW application. Such systems are particularly appropriate for mobile and remote activities, including the activities of personal users without permanent access to reliable and timely communications infrastructures.

@inproceedings{HT79,
   title = {Observations on Practically Perfect CSCW},
   author = {Harold Thimbleby and D. J. Pullinger},
   abstract = {Technical systems are so powerful that there is a temptation to try to provide ``perfect'' support for any cooperative work practice. Some CSCW problems result from designs motivated by optimising technical criteria. A very high bandwidth network, for instance, can support a wide variety of work patterns; the consequent focus of solving the salient technical problems gives the impression that CSCW is a merely social concern. We suggest a class of CSCW system property, {\emph{observational properties\/}}, which are required by users. This motivates a description of an appropriate technology to support such properties. Observational properties tend to be easier to support, so that systems may be more robust or able to handle degradation more gracefully. When an observer cannot distinguish a CSCW system from a perfect system, we say the system is {\emph{practically perfect\/}}. Practically perfect CSCW can be achieved either by perfect technology or, more appropriately, by judicious design of the CSCW application. Such systems are particularly appropriate for mobile and remote activities, including the activities of personal users without permanent access to reliable and timely communications infrastructures.},
   year = {1993},
   booktitle = {Proceedings CSCW (Computer Supported Co-Operative Working) Issues for Mobile and Remote Workers},
   pages = {5/1--5/4},
   series = {Joint CSCW SIG/IEE Colloquium},
   number = {IEE Digest 1993/059}
}

Like many interactive systems, hypertext is operated by button pressing. It is therefore possible to combine an interactive system with its own hypertext manual. Numerous advantages follow: adaptive intelligent interactive help; correct documentation, in natural or mathematical language; automatic generation of conventional manuals optimised for various tasks; and detailed analysis.

This paper motivates the approach, and describes a representative system, Hyperdoc. Hyperdoc enables research questions about good user interfaces and good user manuals to be investigated.

@inproceedings{manuals-bcs,
   title = {Combining Systems and Manuals},
   author = {Harold Thimbleby},
   abstract = {Like many interactive systems, hypertext is operated by button pressing. It is therefore possible to combine an interactive system with its own hypertext manual. Numerous advantages follow: adaptive intelligent interactive help; correct documentation, in natural or mathematical language; automatic generation of conventional manuals optimised for various tasks; and detailed analysis.

This paper motivates the approach, and describes a representative system, {\emph{Hyperdoc\/}}. Hyperdoc enables research questions about good user interfaces and good user manuals to be investigated.},
   year = {1993},
   booktitle = {Proceedings British Computer Society Conference on Human-Computer Interaction, {HCI}'93},
   pages = {479--488},
   isbn = {0--521--46633--4},
   volume = {VIII},
   location = {Loughborough},
   editor = {J. L. Alty and D. Diaper and S. Guest},
   publisher = {Cambridge University Press}
}

@inproceedings{HT80,
   title = {Creative Writing in Hypertext: Beyond Linking Concepts},
   author = {Harold Thimbleby},
   year = {1993},
   booktitle = {Proceedings Conference on Computers {\&} Writing},
   volume = {VI}
}

The value of electronic mail as a medium for collaborative and coordinated work can be enhanced by relating messages to conversations. While some groupware systems have offered such facilities, their ability to assess conversational context is dependent on explicit user action and the use of specific systems by all collaborators.

This paper describes Mona, a novel conversation based email platform. Mona provides a hypertext representation of conversational context without requiring any additional effort from the user or the use of specific email systems by other collaborators. Mona’s lack of requirements and independence is made possible by inferring conversational context with heuristics using information inherently transferred in all email communications.

Mona’s heuristics are described, as are its mechanisms for personalising conversation views.

@inproceedings{HT81,
   title = {Reducing User Effort in Collaboration Support},
   author = {Harold Thimbleby and {\main{A. J. G. Cockburn}}},
   abstract = {The value of electronic mail as a medium for collaborative and coordinated work can be enhanced by relating messages to conversations. While some groupware systems have offered such facilities, their ability to assess conversational context is dependent on explicit user action and the use of specific systems by all collaborators. 

This paper describes Mona, a novel conversation based email platform. Mona provides a hypertext representation of conversational context without requiring any additional effort from the user or the use of specific email systems by other collaborators. Mona's lack of requirements and independence is made possible by inferring conversational context with heuristics using information inherently transferred in all email communications. 

Mona's heuristics are described, as are its mechanisms for personalising conversation views.},
   year = {1993},
   booktitle = {Proceedings 1993 {ACM/SIGCHI} International Conference on Intelligent User Interfaces --- IUI'93},
   pages = {215--218},
   isbn = {0--89791--556--9},
   editor = {W. D. Gray and W. E. Hefley and D. Murray},
   location = {Orlando, Florida},
   publisher = {ACM Press},
   doi = {10.1145/169891.169989}
}

@inbook{HT183,
   title = {An Author's Cross--Referencer},
   author = {Harold Thimbleby},
   year = {1992},
   booktitle = {Computers and Writing},
   pages = {82--98},
   isbn = {1--871516--20--X},
   editor = {P. O'B. Holt and N. Williams},
   publisher = {Intellect Books}
}

Relating individual messages to their on-going conversations enhances the value of electronic mail as a medium for collaborative and coordinated work. Some groupware systems have offered these facilities, but their ability to determine conversational context is dependent on explicit user actions — being told — and the use of specific systems by all users involved.

This paper describes Mona, an email system that provides an automatic hypertext representation of conversational context. Mona is novel in that conversation facilities are provided without requiring any user effort or the use of particular systems by other collaborators. This lack of requirements and independence is made possible by inferring conversational context with heuristics from information inherent in all email communications. Mona’s heuristics are described, together with its central design motivation: that the cost/benefit disparity resulting from dependency on user actions is liable to cause system rejection.

@inproceedings{mona-ozchi,
   title = {Automatic Conversational Context: Avoiding Dependency on User Effort in Groupware},
   author = {Harold Thimbleby and {\main{A. J. G. Cockburn}}},
   abstract = {Relating individual messages to their on-going conversations enhances the value of electronic mail as a medium for collaborative and coordinated work. Some groupware systems have offered these facilities, but their ability to determine conversational context is dependent on explicit user actions --- being told --- and the use of specific systems by all users involved.

This paper describes Mona, an email system that provides an automatic hypertext representation of conversational context. Mona is novel in that conversation facilities are provided without requiring any user effort or the use of particular systems by other collaborators. This lack of requirements and independence is made possible by inferring conversational context with heuristics from information inherent in all email communications. Mona's heuristics are described, together with its central design motivation: that the cost/benefit disparity resulting from dependency on user actions is liable to cause system rejection.},
   year = {1992},
   booktitle = {Proceedings of OZCHI'92, Interface Technology: Advancing Human-Computer Communication, CHISIG Annual Conference},
   pages = {142--149},
   isbn = {0--9595349--9--7},
   editor = {M. J. Rees and R. Iannella},
   location = {Australia}
}

@inproceedings{weak-chi,
   title = {The Weak Science in Human-Computer Interaction},
   author = {Harold Thimbleby and S. Greenberg},
   year = {1992},
   booktitle = {Proceedings ACM CHI'92 Research Symposium},
   note = {Also Department of Computer Science University of Calgary Research Report 91/459/43}
}

@inproceedings{HT84,
   title = {The Future of Viruses},
   author = {Harold Thimbleby},
   year = {1992},
   booktitle = {Proceedings of The NCC Information Technology Conference}
}

@inproceedings{HT85,
   title = {Intelligent Consumer Products},
   author = {Harold Thimbleby},
   year = {1992},
   booktitle = {Proceedings Intelligent Consumer Products},
   pages = {2/1--2/3},
   series = {IEE/CSD Joint Colloquium},
   number = {IEE Digest 1992/013}
}

@inbook{HT182,
   title = {HyperCard: An Object Oriented Disappointment},
   author = {Harold Thimbleby and S. Jones and A. J. G. Cockburn},
   year = {1992},
   booktitle = {Building Interactive Systems: Architectures and Tools},
   pages = {35--55},
   isbn = {3--540--19736--2},
   editor = {P. D. Gray and R. Took},
   publisher = {Springer Verlag}
}

@inproceedings{HT83,
   title = {Belief Representation and Agent Architectures},
   author = {Harold Thimbleby and {\main{S. P. Marsh}}},
   year = {1992},
   booktitle = {Proceedings of the Third Belief Representation and Agent Architectures Workshop, BRAA'92},
   note = {University of Durham Engineering and Computer Science TR 6/92},
   pages = {97--125}
}

@article{HT224,
   title = {Ted Nelson and His 2020 Vision},
   author = {Harold Thimbleby and G. F. Coulouris},
   year = {1991},
   pages = {8--9},
   journal = {Computer Bulletin, Series IV},
   volume = {3},
   number = {3}
}

@inproceedings{HT86,
   title = {Formal Methods without Psychology},
   author = {Harold Thimbleby},
   year = {1991},
   booktitle = {Proceedings Theory in Human-Computer Interaction},
   pages = {6/1--6/6},
   series = {IEE Colloquium},
   number = {IEE Digest 1991/192}
}

@article{liveware-ijhcs,
   title = {A New Approach to Sharing Data in Social Networks},
   author = {Harold Thimbleby and S. Greenberg and I. H. Witten and G. F. Coulouris},
   year = {1991},
   pages = {337--348},
   journal = {International Journal of Man-Machine Studies},
   volume = {34},
   number = {3}
}

@article{HT23,
   title = {A Reflexive Perspective of CSCW},
   author = {Harold Thimbleby and A. J. G. Cockburn},
   year = {1991},
   pages = {63--68},
   journal = {ACM SIGCHI Bulletin},
   volume = {23},
   number = {3}
}

For many years, computer scientists have been concerned with whether computers can think. Considerable thought, therefore, goes into designing “thinking” computer systems and into wondering whether they really can think or just pretend to. On the other hand, it is “obvious” that humans can think, and therefore little thought has gone into the related question, “can humans think?” This paper explores the ergonomic implications of the affirmative answer.

Computers get better treatment than humans, yet humans are more than machines. However not only do designers seem to forget this, but they don’t even treat users with the same respect as they would a machine.

@article{think-ergonomicsj,
   title = {Can Humans Think? The Ergonomics Society Annual Lecture},
   author = {Harold Thimbleby},
   abstract = {For many years, computer scientists have been concerned with whether computers can think. Considerable thought, therefore, goes into designing ``thinking'' computer systems and into wondering whether they really can think or just pretend to. On the other hand, it is ``obvious'' that humans can think, and therefore little thought has gone into the related question, ``can humans think?'' This paper explores the ergonomic implications of the affirmative answer.

Computers get better treatment than humans, yet humans are more than machines. However not only do designers seem to forget this, but they don't even treat users with the same respect as they would a machine.},
   year = {April 1991},
   pages = {1269--1287},
   journal = {Ergonomics},
   volume = {34},
   highlight = {Ergonomics Society Annual Lecture},
   number = {10}
}

@article{HT24,
   title = {Can Viruses Ever Be Useful?},
   author = {Harold Thimbleby},
   year = {1991},
   pages = {111--114},
   journal = {Computers and Security},
   volume = {10},
   number = {2}
}

@inproceedings{HT87,
   title = {Sharing HyperCard Stacks},
   author = {Harold Thimbleby},
   year = {1991},
   booktitle = {Proceedings 7th Annual Apple European University Consortium Conference},
   pages = {68--71},
   location = {Paris}
}

@inproceedings{HT88,
   title = {Low tech {\LaTeX}},
   author = {Harold Thimbleby},
   year = {1991},
   booktitle = {Proceedings Computers {\&} Writing},
   pages = {124--130},
   volume = {IV},
   editor = {M. Sharples},
   location = {Brighton}
}

@inbook{HT185,
   title = {A New Approach to Sharing Data in Social Networks},
   author = {Harold Thimbleby and S. Greenberg and I. H. Witten and G. F. Coulouris},
   year = {1991},
   booktitle = {Computer Supported Cooperative Work and Groupware},
   pages = {211--222},
   isbn = {0--12--299220--2},
   editor = {S. Greenberg},
   publisher = {Academic Press}
}

@inproceedings{HT90,
   title = {Visible Aspects of Text},
   author = {Harold Thimbleby and {\main{R. J. Watt}} and J. Bock and A. Wilkins},
   year = {1990},
   booktitle = {Proceedings Applying Visual Psychophysics to User Interface Design},
   pages = {309--325},
   location = {London}
}

@inproceedings{HT93,
   title = {Virus Theory},
   author = {Harold Thimbleby and S. O. Anderson},
   year = {1990},
   booktitle = {Proceedings Workshop on Viruses and Their Future Impact on Computing Systems},
   pages = {4/1--4/5},
   number = {IEE Digest 1990/132}
}

@article{HT25,
   title = {The ``Worm'' Programs --- Early Experience with a Distributed Intelligence},
   author = {Harold Thimbleby and I. H. Witten},
   year = {1990},
   pages = {14--17},
   journal = {ACM SIGART Bulletin},
   volume = {1},
   number = {2}
}

CSCW (Computer Supported Cooperative Work) is an active research area with many promising applications and benefits. We argue that the plight of the individual user can also be viewed as a CSCW problem, for the individual frequently acts as multiple persona: performing many independent tasks, perhaps in several places. We propose reflexive CSCW to address such issues. Solutions in the reflexive case will of course be of benefit to users even if they are working in a conventional multi-user CSCW context; proposed solutions in CSCW can be re-presented for individual users.

@article{cscw-iwc,
   title = {Reflexive {CSCW}: Supporting Cooperative Long-Term Personal Work},
   author = {Harold Thimbleby and S. O. Anderson and I. H. Witten},
   abstract = {CSCW (Computer Supported Cooperative Work) is an active research area with many promising applications and benefits. We argue that the plight of the individual user can also be viewed as a CSCW problem, for the individual frequently acts as multiple persona: performing many independent tasks, perhaps in several places. We propose {\emph{reflexive\/}} CSCW to address such issues. Solutions in the reflexive case will of course be of benefit to users even if they are working in a conventional multi-user CSCW context; proposed solutions in CSCW can be re-presented for individual users.},
   year = {1990},
   pages = {330--336},
   journal = {Interacting with Computers},
   volume = {2},
   number = {3}
}

@article{bugs-iwc,
   title = {You're Right About the Cure: Don't Do That},
   author = {Harold Thimbleby},
   year = {1990},
   pages = {8--25},
   journal = {Interacting with Computers},
   volume = {2},
   number = {1}
}

@inproceedings{HT92,
   title = {Viruses and Their Impact on Future Computing Systems},
   author = {Harold Thimbleby},
   year = {1990},
   booktitle = {Proceedings Workshop on Viruses and Their Future Impact on Computing Systems},
   pages = {1/1--1/4},
   series = {IEE Colloquium},
   number = {IEE Digest 1990/132}
}

@inproceedings{HT91,
   title = {Liveware: A Personal Distributed CSCW},
   author = {Harold Thimbleby},
   year = {1990},
   booktitle = {Proceedings CSCW: Computer Supported Co-operative Work},
   pages = {6/1--6/4},
   number = {IEE Digest 1990/133},
   series = {IEE Colloquium}
}

@inbook{HT187,
   title = {The Role of Formal Methods in Human-Computer Interaction},
   author = {Harold Thimbleby and Michael D. Harrison},
   year = {1990},
   booktitle = {Formal Methods in Human Computer Interaction},
   pages = {1--8},
   isbn = {0--521--37202 X},
   editor = {Michael D. Harrison and H. Will Thimbleby},
   publisher = {Cambridge University Press}
}

@article{HT225,
   title = {Artificial Life},
   author = {Harold Thimbleby},
   year = {1990},
   pages = {22--23},
   journal = {Computer Bulletin, Series IV},
   volume = {2},
   number = {4},
   crossref = {cbreferences1990}
}

@inproceedings{HT94,
   title = {On Formal Methods in {HCI}, {IEE} Colloquium},
   author = {Harold Thimbleby},
   year = {1989},
   booktitle = {Proceedings Workshop on Formal Methods in {HCI}},
   pages = {1/--1/},
   volume = {III},
   number = {IEE Digest 1989/151}
}

The inner loop of insert sort can he simplified by using a sentinel value. We suggest a way of avoiding the extra storage normally required for the sentinel, and a way of avoiding the prior, and possibly restrictive, choice of its value. Algorithms are given in Pascal.

@article{insert-spae,
   title = {Using Sentinels in Insert Sort},
   author = {Harold Thimbleby},
   abstract = {The inner loop of insert sort can he simplified by using a sentinel value. We suggest a way of avoiding the extra storage normally required for the sentinel, and a way of avoiding the prior, and possibly restrictive, choice of its value. Algorithms are given in Pascal.},
   year = {1989},
   pages = {303--307},
   journal = {Software --- Practice {\&} Experience},
   volume = {19},
   number = {3},
   doi = {10.1002/spe.4380190308}
}

@article{HT29,
   title = {A Literate Program for File Comparison},
   author = {Harold Thimbleby},
   year = {1989},
   pages = {740--755},
   journal = {Communications of the ACM},
   volume = {32},
   number = {6}
}

Ded is a text display editor designed by computer scientists. The design is characterised by simplicity and adherence to user interface principles. This has led to a good design but with contentious features. This chapter highlights the conflict between principles and features, particularly in the social context in which ded was designed.

@inbook{HT188,
   title = {The Life and Times of {Ded}, Display Editor},
   author = {Harold Thimbleby and R. Bornat},
   abstract = {Ded is a text display editor designed by computer scientists. The design is characterised by simplicity and adherence to user interface principles. This has led to a good design but with contentious features. This chapter highlights the conflict between principles and features, particularly in the social context in which ded was designed.},
   year = {1989},
   booktitle = {Cognitive Ergonomics and Human Computer Interaction},
   pages = {225--255},
   isbn = {0--521--37179--1},
   editor = {J. B. Long and A. Whitefield},
   publisher = {Cambridge University Press}
}

The Leidenfrost Phenomena arises when a heated object becomes insulated by a vapour layer. Vapour generation may also sustain oscillation. The Leidenfrost Phenomenon is easily studied using simple apparatus and water, and beautiful oscillations may be observed.

@article{HT26,
   title = {The Leidenfrost Phenomenon},
   author = {Harold Thimbleby},
   abstract = {The Leidenfrost Phenomena arises when a heated object becomes insulated by a vapour layer. Vapour generation may also sustain oscillation. The Leidenfrost Phenomenon is easily studied using simple apparatus and water, and beautiful oscillations may be observed.},
   year = {1989},
   pages = {300--303},
   journal = {Physics Education},
   volume = {24},
   number = {5}
}

@article{HT27,
   title = {Worms and Bugs in the Church-Turing Thesis},
   author = {Harold Thimbleby and I. H. Witten},
   year = {1989},
   pages = {3--4},
   journal = {Canadian Artificial Intelligence},
   number = {21}
}

@article{HT28,
   title = {Bugs in the Church-Turing Thesis},
   author = {Harold Thimbleby and I. H. Witten},
   year = {1989},
   pages = {17--18},
   journal = {Canadian Artificial Intelligence},
   number = {19}
}

@inproceedings{bugs-bcs,
   title = {Bugs: The Issue Facing {HCI}},
   author = {Harold Thimbleby},
   year = {1989},
   booktitle = {Proceedings British Computer Society Conference on Human Computer Interaction, {HCI}'89},
   aftertitle = {Keynote},
   pages = {105--107},
   isbn = {0--521--38430--3},
   volume = {V},
   location = {Nottingham},
   editor = {A.~Sutcliffe and L.~Macaulay},
   publisher = {Cambridge University Press}
}

Delaying commitment means keeping your options open, with inventive consequences. Algorithms and other techniques make delaying commitment an effective strategy.

@article{HT30,
   title = {Delaying Commitment},
   author = {Harold Thimbleby},
   abstract = {Delaying commitment means keeping your options open, with inventive consequences. Algorithms and other techniques make delaying commitment an effective strategy.},
   year = {1988},
   pages = {78--86},
   journal = {IEEE Software},
   volume = {5},
   number = {3}
}

@inproceedings{HT95,
   title = {Modes, {WYSIWYG} and The von Neumann Bottleneck},
   author = {Harold Thimbleby},
   year = {1988},
   booktitle = {Proceedings Workshop on Formal Methods and Human-Computer Interaction},
   volume = {II},
   number = {IEE Digest 1988/82}
}

@inproceedings{HT96,
   title = {Interaction Models and The Principled Design of Interactive Systems},
   author = {Harold Thimbleby and A. J. Dix and Michael D. Harrison and C. Runciman},
   year = {1987},
   booktitle = {Proceedings European Software Engineering Conference},
   pages = {127--135},
   editor = {H. Nichols and D. S. Simpson},
   publisher = {Springer Verlag}
}

@inproceedings{HT97,
   title = {Formal Methods and Human-Computer Interaction, {IEE} Colloquium},
   author = {Harold Thimbleby},
   year = {1987},
   booktitle = {Proceedings Workshop on Formal Methods and Human-Computer Interaction},
   number = {{IEE} Digest No. 1987/09}
}

A simple algorithm for menu selection, which enhances existing methods for small menus (e.g., fewer than 20 entries) is discussed. Algorithms are presented in Pascal.

@article{menu-bit,
   title = {A Menu Selection Algorithm},
   author = {Harold Thimbleby},
   abstract = {A simple algorithm for menu selection, which enhances existing methods for small menus (e.g., fewer than 20 entries) is discussed. Algorithms are presented in Pascal.},
   year = {1987},
   pages = {89--94},
   journal = {Behaviour and Information Technology},
   volume = {6},
   number = {1},
   doi = {10.1080/01449298708901819}
}

@article{optimising-cj,
   title = {Optimising Self-Replicating Programs},
   author = {Harold Thimbleby},
   year = {1987},
   pages = {475--476},
   journal = {Computer Journal},
   volume = {30},
   number = {5}
}

Character-mapped display terminals very considerably. TIP is a Terminal Independent Package which conceals the details of efficiently handling terminal protocols from applications programs. There is a conflict between the ability to handle esoteric terminal features and providing a uniform programmer’s interface for all terminals. This paper discusses the conflicts and the design approach which resolved them.

@article{tip-spae,
   title = {The Design of a Terminal Independent Package},
   author = {Harold Thimbleby},
   abstract = {Character-mapped display terminals very considerably. TIP is a Terminal Independent Package which conceals the details of efficiently handling terminal protocols from applications programs. There is a conflict between the ability to handle esoteric terminal features and providing a uniform programmer's interface for all terminals. This paper discusses the conflicts and the design approach which resolved them.},
   year = {1987},
   pages = {351--367},
   journal = {Software --- Practice {\&} Experience},
   volume = {17},
   doi = {10.1002/spe.4380170505},
   number = {15}
}

@inproceedings{innovative-bcs,
   title = {The Design of Two Innovative User Interfaces},
   author = {Harold Thimbleby},
   year = {1986},
   booktitle = {Proceedings British Computer Society Conference on Human Computer Interaction, {HCI}'86},
   pages = {336--351},
   isbn = {0--521--33259--1},
   editor = {Michael D. Harrison and A. F. Monk},
   location = {York},
   publisher = {Cambridge University Press}
}

@inproceedings{sam-bcs,
   title = {Ease of Use --- The Ultimate Deception},
   author = {Harold Thimbleby},
   year = {1986},
   booktitle = {Proceedings British Computer Society Conference on Human Computer Interaction, {HCI}'86},
   aftertitle = {Keynote},
   pages = {78--94},
   isbn = {0--521--33259--1},
   editor = {M.~D.~Harrison and A.~F.~Monk},
   location = {York},
   publisher = {Cambridge University Press}
}

@inproceedings{HT98,
   title = {The {TIN}: An Approach to Powerful and Cheap User Interfaces},
   author = {Harold Thimbleby and G. S. Macfarlane},
   year = {1986},
   booktitle = {Proceedings 8th. International Conference on Computer Communication, {ICCC}'86},
   pages = {238--241},
   location = {Munich},
   editor = {P. J. Kuehn},
   publisher = {North-Holland}
}

Cweb is a literate programming system for the programming language C. Experience developing and using it forms the basis of this paper, the purpose of which is to:

• support Knuth’s enthusiasm for literate programming
• discuss developments in literate programming support, both within the current framework of cweb and to interactive graphics support
• discuss the implementation issues, considering cweb as part of a simple IPSE (Integrated Project Support Environment); the conclusions for IPSEs appear pessimistic.

@article{cweb-cj,
   title = {Experiences with Literate Programming Using CWEB (A Variant of Knuth's WEB)},
   author = {Harold Thimbleby},
   abstract = {{\textbf{Cweb}} is a literate programming system for the programming language C{\@}. Experience developing and using it forms the basis of this paper, the purpose of which is to: {\begin{itemize}}{\item} support Knuth's enthusiasm for literate programming {\item} discuss developments in literate programming support, both within the current framework of {\textbf{cweb}} and to interactive graphics support {\item} discuss the implementation issues, considering {\textbf{cweb}} as part of a simple IPSE (Integrated Project Support Environment); the conclusions for IPSEs appear pessimistic.{\end{itemize}}},
   year = {1986},
   pages = {201--211},
   journal = {Computer Journal},
   volume = {29},
   highlight = {Awarded British Computer Society Wilkes Medal},
   number = {3}
}

One view of interactive computer systems is that the user, having problems to solve, supplies the “givens” of these problems to the machine, which in response supplies as output the “unknowns.” Reassigning or discarding these labels “givens” and ‘unknown” is a time-honoured heuristic for problem-solving. Also, people seem to prefer interpretations without such labels for fast interactive systems, and mere speed in systems that do embody fixed distinctions between input and output often contributes little towards ease of useÑit may only serve to emphasize a frustrating mechanical dumbness. We therefore apply the same heuristic to the design of interactive computer systems, noting that a number of existing successful interactive system styles can be viewed as the outcome of this approach.

@article{eo-ijhcs,
   title = {Equal Opportunity Interactive Systems},
   author = {Harold Thimbleby and C. Runciman},
   abstract = {One view of interactive computer systems is that the user, having problems to solve, supplies the ``givens'' of these problems to the machine, which in response supplies as output the ``unknowns.'' Reassigning or discarding these labels ``givens'' and `unknown'' is a time-honoured heuristic for problem-solving. Also, people seem to prefer interpretations without such labels for fast interactive systems, and mere speed in systems that do embody fixed distinctions between input and output often contributes little towards ease of useÑit may only serve to emphasize a frustrating mechanical dumbness. We therefore apply the same heuristic to the design of interactive computer systems, noting that a number of existing successful interactive system styles can be viewed as the outcome of this approach.},
   year = {1986},
   pages = {439--451},
   journal = {International Journal of Man-Machine Studies},
   volume = {25},
   doi = {10.1016/S0020-7373(86)80070-0},
   number = {4}
}

User engineering principles may be formalised as theorems over specifications of interactive systems. In this paper we discuss some different categories of user engineering principle and expose issues that must be resolved to produce effective formalisation.

@inproceedings{formalising-bcs,
   title = {Formalising Guidelines for the Design of Interactive Systems},
   author = {Harold Thimbleby and Michael D. Harrison},
   abstract = {User engineering principles may be formalised as theorems over specifications of interactive systems. In this paper we discuss some different categories of user engineering principle and expose issues that must be resolved to produce effective formalisation.},
   year = {1985},
   booktitle = {Proceedings British Computer Society Conference on Human Computer Interaction, {HCI}'85},
   pages = {161--171},
   isbn = {0--521--32066--6},
   editor = {S. Cook and P. Johnson},
   location = {Norwich},
   publisher = {Cambridge University Press}
}

@article{HT31,
   title = {Failure in the Technical User Interface Design Process},
   author = {Harold Thimbleby},
   year = {1985},
   pages = {187--193},
   journal = {Computers and Graphics},
   volume = {9},
   number = {3}
}

Generative user-engineering principles are assertions about interactive system behaviour and have equivalent colloquial forms. Current work shows that they are a promising contribution to the design of acceptable user interfaces, because they effectively bridge the conceptual gap between designer and user. In colloquial form a generative user-engineering principle can be used to help clarify requirements in participative design, or to explicate documentation. In rigorous form, generative user-engineering principles provide a constructive higher order consistency on user interfaces.

@inproceedings{guep2-interact,
   title = {Generative User-Engineering Principles for User Interface Design},
   author = {Harold Thimbleby},
   abstract = {Generative user-engineering principles are assertions about interactive system behaviour and have equivalent colloquial forms. Current work shows that they are a promising contribution to the design of acceptable user interfaces, because they effectively bridge the conceptual gap between designer and user. In colloquial form a generative user-engineering principle can be used to help clarify requirements in participative design, or to explicate documentation. In rigorous form, generative user-engineering principles provide a constructive higher order consistency on user interfaces.},
   year = {1985},
   booktitle = {Proceedings First {IFIP} Conference on Human-Computer Interaction --- {Interact} 1984},
   note = {(983pp)},
   pages = {661--666},
   isbn = {0--444--87773--8},
   editor = {B. Shackel},
   publisher = {North-Holland},
   location = {London}
}

Generative user-engineering principles are assertions about interactive system behaviour and have equivalent colloquial forms. Current work shows that they are a promising contribution to the design of acceptable user interfaces, because they effectively bridge the conceptual gap between designer and user. In colloquial form a generative user-engineering principle can be used to help clarify requirements in participative design, or to explicate documentation. In rigorous form, generative user-engineering principles provide constructive higher order consistency on user interfaces.

Note. An updated discussion can be found in my User Interface Design (Addison-Wesley, 1990).

@inproceedings{guep-interact,
   title = {Generative User-Engineering Principles for User Interface Design},
   author = {Harold Thimbleby},
   abstract = {Generative user-engineering principles are assertions about interactive system behaviour and have equivalent colloquial forms. Current work shows that they are a promising contribution to the design of acceptable user interfaces, because they effectively bridge the conceptual gap between designer and user. In colloquial form a generative user-engineering principle can be used to help clarify requirements in participative design, or to explicate documentation. In rigorous form, generative user-engineering principles provide constructive higher order consistency on user interfaces.

Note. An updated discussion can be found in my {\emph{User Interface Design\/}} (Addison-Wesley, 1990).},
   year = {1984},
   booktitle = {Proceedings First {IFIP} Conference on Human-Computer Interaction --- {Interact} 1984},
   pages = {102--107},
   volume = {2},
   editor = {B. Shackel},
   location = {London}
}

@article{edit-bit,
   title = {Guidelines for `Manipulative' Editing},
   author = {Harold Thimbleby},
   year = {1983},
   pages = {127--161},
   journal = {Behaviour and Information Technology},
   volume = {2},
   number = {2}
}

@article{HT32,
   title = {Designing Word Processors: Principle and Prejudice},
   author = {Harold Thimbleby},
   year = {1983},
   pages = {239--244},
   journal = {Information Design Journal},
   volume = {3},
   number = {3}
}

@inproceedings{HT100,
   title = {Interactive Systems Design: {A} Personal View},
   author = {Harold Thimbleby},
   year = {1982},
   booktitle = {Proceedings {IEE} Conference Man/Machine Systems},
   pages = {118--122},
   isbn = {9--85296264--9},
   location = {Manchester},
   number = {IEE Publication 212}
}

@article{ambiguity-ijhcs,
   title = {Character Level Ambiguity: Consequences for User Interface Design},
   author = {Harold Thimbleby},
   year = {1982},
   pages = {211--225},
   journal = {International Journal of Man-Machine Studies},
   volume = {16}
}

@inproceedings{HT101,
   title = {Basic User Engineering Principles for Display Editors},
   author = {Harold Thimbleby},
   year = {1982},
   booktitle = {Proceedings 6th. International Conference on Computer Communication, ICCC'82},
   pages = {537--542},
   isbn = {0--444--86464--4},
   editor = {M. B. Williams},
   location = {London},
   publisher = {North Holland}
}

A simple yet flexible method of editing text is described which is applicable to all forms of character based command processing applications. The technique greatly increases the friendliness of a text driven interface but does not interfere with most existing command conventions; it can also be generalised to form the basis of a powerful and easy to use text editor. This paper describes the details and basic philosophy of the editing interface and describes its successful use in two applications (command processor and calculator) which are not normally associated with text editing requirements.

@article{HT33,
   title = {A Text Editing Interface: Definition and Use},
   author = {Harold Thimbleby},
   abstract = {A simple yet flexible method of editing text is described which is applicable to all forms of character based command processing applications. The technique greatly increases the friendliness of a text driven interface but does not interfere with most existing command conventions; it can also be generalised to form the basis of a powerful and easy to use text editor. This paper describes the details and basic philosophy of the editing interface and describes its successful use in two applications (command processor and calculator) which are not normally associated with text editing requirements.},
   year = {1982},
   pages = {25--40},
   journal = {Computer Languages},
   volume = {7},
   number = {1}
}

@inproceedings{HT102,
   title = {A Text Display Editor as a Terminal Driver},
   author = {Harold Thimbleby},
   year = {1981},
   booktitle = {Proceedings Document Preparation Systems},
   pages = {13--14},
   location = {Lausanne}
}

@article{word-cj,
   title = {A Word Boundary Algorithm for Text Processing},
   author = {Harold Thimbleby},
   year = {1981},
   pages = {249--255},
   journal = {Computer Journal},
   volume = {24},
   number = {3}
}

@article{dd-ijhcs,
   title = {Dialogue Determination},
   author = {Harold Thimbleby},
   year = {1980},
   pages = {295--304},
   journal = {International Journal of Man-Machine Studies},
   volume = {13},
   number = {3}
}

@article{leave-spae,
   title = {Leave and Recall: Primitives for Procedural Programming},
   author = {Harold Thimbleby},
   year = {1980},
   pages = {127--134},
   journal = {Software --- Practice {\&} Experience},
   volume = {10},
   number = {2},
   doi = {10.1002/spe.4380100204}
}

@inproceedings{HT103,
   title = {Interactive Technology: The Role of Passivity},
   author = {Harold Thimbleby},
   year = {1979},
   booktitle = {Proceedings 23rd. Annual Human Factors Conference},
   pages = {80--84},
   editor = {C. K. Bensel},
   location = {Boston, USA}
}

@article{HT35,
   title = {Dreams},
   author = {Harold Thimbleby},
   year = {1979},
   pages = {601--608},
   journal = {Self and Society},
   volume = {7},
   number = {6}
}

@article{HT34,
   title = {Computers and Human Consciousness},
   author = {Harold Thimbleby},
   year = {1979},
   pages = {241--243},
   journal = {Computers and Education},
   volume = {3},
   number = {3}
}

@article{HT233,
   title = {A Note on Menu Selection},
   author = {Harold Thimbleby},
   year = {1978},
   pages = {20, 21 {\&} 23},
   journal = {Computer Bulletin, Series 2},
   number = {18}
}