`
`TOM CAREY
`
`‘
`
`JENNY PREECE
`
`YVONNE ROGERS
`
`HELEN SHARP
`
`DAVID BENIION
`
`SIMON HOLLAND
`
`ADDISON-WESLEY
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`SCEA EX. 1013 Page 1
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`SCEA Ex. 1013 Page 1
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`

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`
`
`Edinburgh Gate
`Harlow
`Essex. CM20 ZJE
`England
`
`All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in
`any form or by any means, electronic. mechanical, photocopying, recording or otherwise, without prior written
`permission of the publisher.
`
`Tire programs presented in this book have been included for their instructional value. They have been tested
`with care but are not guaranteed for any particular purpose. The publisher does not offer any warranties or
`representations, nor does it accept any liabilities with respect to the programs. '
`
`Many of the designations used by manufacturers and sellers to distinguish their products are claimed as
`trademarks. Addison-Wesley has made every attempt to supply trademark information about manufacturers and
`their products mentioned in this book. A list of the trademark designations and their owners appears below.
`EDI'I'ORJNrCHIEF: Simon Plurntree
`PRODUCFIUN MANAGER: Stephen Bishop
`PRODUCTION Ebt'roa: Susan Keany
`Paoouc rroN CONTROLLER: Jim Altman
`TEXT DESIGNER: Valerie O’Donnell
`it.L.USTRATIONSI Chartwell illustrators
`TYPESE'lTERS: CRB Associates, Norwich
`COVER Dasronerzs: Designers & Partners, Oxford
`PRINTED AND BOUND in Great Britain by Biddles Ltd, Guildford and King’s Lynn
`
`First printed 1994. Reprinted 1995 (twice) and 1996. Reprinted 1997' (twice)
`
`British Library Cataloguing in Publication Data
`A. catalogue record for this book is available from the British Library.
`
`Library of Congress Cataloging in Publication Data
`Preece. Jenny.
`Human-computer interaction 1' Jenny Preece lwith] Yvonne Rogers .
`let alr].
`p.
`cm.
`Includes bibliographical references and index.
`ISBN 0A20|~62769-8
`l. Human—computer interaction.
`QA76.9.H85P74
`1994
`004’.Dl‘9—d020
`
`1. Title.
`
`94-16158
`CIP
`
`.
`
`.
`
`Trademark notice
`
`MacPaint. QuiCkTthlC, MacDraw. HyperCard and Macintosh are trademarks of Apple Computer Inc.
`Excel, Word, Microsoft and Windows for Workgroups are trademarks of Microsoft Corporation
`Postiit is a trademark of 3M
`UNIX is a trademark of UNIX System Laboratories Inc.
`VODIS is a trademark of Britiin Telecom, Logica (Cambridge) Ltd, Cambridge University
`Private Eye is a trademark of Reflection Technology
`SuperBook is a trademark of AT & T
`Telstar is a traderrrark of British Telecom
`DataView is a trademark of V1 Corp.
`PARTS Workbench is a trademark of Digitaik Inc.
`XII Windows System is a trademark of Massachusetts institute of Technology
`Prograplt is a trademark of Gunakara Sun Systems Ltd
`[HM/X is a trademark of Visual Edge Software Ltd
`Etchasketeh is a trademark of Peter Pan Playthings Ltd
`MaeroMind Director is a trademark of Macromedia
`Data GloVe is a trademark of VPL
`
`IJ-
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`SCEA EX. 1013 Pa 8 2
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`SCEA Ex. 1013 Page 2
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`

`

`Contents
`
`Foreword
`
`Preface
`
`Readership
`How to use this book
`
`About the Authors
`
`The Story of this Book and Acknowledgements
`
`Acknowledgements
`
`messes
`seem”
`
`
`PART I
`
`Introduction
`
`1 What is HCI?
`
`
`
`1.1
`1.2
`1.3
`1.4
`
`Technological change: Different design needs
`The challenge of HCl
`The goals of HCI
`HC1 and its evolution
`
`The importance oil-1C1: Productivity
`1.5
`1.6 When things go wrong
`
`2 Components of HCI
`
`2.1
`2.2
`2.3
`2.4
`
`HCI as interdisciplinary practice
`Disciplines contributing to HCI
`A conceptual model for I-lCI
`Designing HCI
`
`Interview with Terry Winograd
`
`
`
`SCEA Ex. 1013 Page 3
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`SCEA Ex. 1013 Page 3
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`

`‘
`
`
`
`.
`
`3 Cognitive Frameworks for HCI
`3.1
`A cognitive perspective
`3.2
`Broadening the cognitive framework
`
`4 Perception and Representation
`4.1
`Visual perception
`4.2
`Graphical representation at the interface
`
`5 Attention and Memory Constraints
`5.1
`Focusing attention
`5.2
`Memory constraints
`6 Knowledge and Mental Models
`6.1
`Knowledge representation and organization
`6.2
`Mental models
`6.3
`The utility of mental models in HCI
`
`7
`
`Interface Metaphors and Conceptual Models
`7.1
`Verbal metaphors
`7.2
`Virtual interface metaphors
`7.3
`Classification of interface metaphors for applications
`7.4
`Ubiquitous computing
`7.5
`Conceptual models
`
`8 Learning in Context
`
`8.1
`8.2
`8.3
`8.4
`
`Learning as an active process
`Gaining expertise
`Psychoiogy of programming
`Collaborative and situated learning
`
`9 Social Aspects
`
`9.1
`9.2
`9.3
`
`Analysing conversation
`Group communication
`Group working in context
`
`10 Organizational Aspects
`
`10.1
`
`10.2
`
`The nature of organizations
`
`The impact of information technology on organizations
`
`
`
`f1
`f
`a}
`
`f
`1T- '
`’5 1
`1,.
`
`| I
`
`+ '
`3‘
`v
`‘ ‘5
`r.
`'
`i
`
`_
`
`I
`
`f
`
`5'1
`'1‘
`
`‘
`
`
`
`SCEA EX. 1013 Pa 6 4
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`SCEA Ex. 1013 Page 4
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`

`

`Interview with Marilyn Mantei
`
`
`,.
`..
`.
`. Wfififi’fi .
`"
`AR lll Humans and Technology: Technology
`
`Interview with Ben Shneiderman
`
`1 1
`
`Input
`Input devices
`11.]
`A sample of input issues: Keyboards
`11.2
`Pointing devices
`11.3
`11.4 Matching devices with work
`11.5 Matching devices with users: Input for the disabled
`11.6 Matching devices with environments of use
`11.7 Developments in input
`
`12 Output
`12.1
`Devices and output
`12.2
`Visual output
`12.3 Dynamic visualizations
`12.4
`Sound output
`12.5
`Speech output
`12.6 Developments in output
`
`13
`
`Interaction Styles
`13.1
`Interaction styles
`13.2
`Command entry
`13.3 Menus and navigation
`13.4
`Form-fills and spreadsheets
`13.5 Natural language dialogue
`13.6 Direct manipulation
`13.7
`Cognitive issues in direct manipulation
`
`14 Designing Windowing Systems
`14.]
`General issues
`14.2
`Basic window components
`14.3
`Common tasks in windowing systems
`14.4
`Issues in windowing systems for CSCW
`
`SCEA EX. 1013 Page 5
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`

`

`15.3 Hypertext and hypermedia
`15.4
`Designing hypermedia for training in HCI
`
`16 Designing for Collaborative Work and Virtual
`Environments
`
`Computer supported cooperative work
`16.1
`16.2 Virtual environments and virtual reality
`16.3 Design trade-offs: An environment for learning about motion
`
`Interview with Roy Kalawsky
`
`
`
`.
`..
`..
`.
`.
`--
`-
`Q Kmfix afiwafififi‘s’emfimfi
`
`
`PART W Interaction Design: Methods and he niques
`
`Interview with Tom Moran
`
`17 Principles of User-Centred Design
`17.1
`Fundamentals
`
`17.2
`17.3
`17.4
`
`The design of software systems
`Two examples of user-centred design
`The scope of human—computer system design
`
`18 Methods for User-Centred Design
`
`Soft systems methodology
`18.1
`Cooperative design
`18.2
`18.3 Multiview: A user-centred approach
`18.4 An HCI design approach
`
`19 Requirements Gathering
`
`Functional requirements
`19.1
`19.2 Data requirements
`19.3
`Usability requirements
`19.4
`Relationship between requirements and usability
`
`20 Task Analysis
`
`20.]
`
`Goals, tasks and actions
`
`20.2 Hierarchical task analysis
`20.3
`Cognitive task analysis
`20.4 Modelling ‘how to do it’ knowledge
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`SCEA Ex. 101% Page 6
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`

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`21 Structured HCI Design
`
`A framework for design
`21.1
`21.2 Conceptual design example: Euroc'hange
`21.3
`From logical to physical design: Task allocation
`21.4
`Physical design
`21.5
`Completing the design
`
`22 Envisioning Design
`
`22.1
`22.2
`22.3
`
`Holistic design
`Sketching and metaphor
`Scenarios, storyboards and snapshots
`
`
`
`
`
`PART V Interaction Design: Support for designers
`
`Interview with Bill Verplank
`
`23 Supporting Design
`
`Supporting the design process
`23.1
`Supporting designers
`23.2
`Supporting design teams
`23.3
`23.4 Different kinds of support
`
`24 Guidelines: Principles and Rules
`
`Principles and rules
`24.1
`24.2 Where do guidelines come from?
`24.3
`Evaluating guidelines
`24.4 An example of applying conflicting guidelines
`
`25 Standards and Metrics
`
`25.1
`25.2
`25.3
`
`Standards and standardization
`Software standards
`HCI standards
`
`25.4 House style guides
`25.5 Metrics
`
`26 Design Rationale
`26.1
`IBIS
`
`26.2
`26.3
`
`Design space analysis
`Claims analysis
`
`SCEA EX. 1013 Page 7
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`SCEA Ex. 1013 Page 7
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`27.2
`27.3
`
`Prototyping to support design
`Software prototyping tools
`
`28 Software Support
`28.1
`The user interface and software tooling
`28.2
`Stand-alone tools
`28.3
`lntegrated environments
`28.4
`Support tools for group working
`
`Interview with Deborah Hix
`
` PART VI interaction Design: Evaluation
`
`Interview with Brian Shackel
`
`29 The Role of Evaluation
`29.1 What do you want to know and why?
`29.2 When and how do you do evaluation?
`
`30 Usage Data: Observations, Monitoring, Users’ Opinions
`30.1
`Observing users
`30.2 Verbal protocols
`30.3
`Software logging
`30.4
`Users’ opinions: Interviews and questionnaires
`
`31 Experiments and Benchmarking
`31.1
`Traditional experiments
`31.2 Usability engineering
`
`32 Interpretive Evaluation
`32.1
`Contextual inquiry
`32.2 Cooperative and participative evaluation
`32.3
`Ethnography
`
`33 Predictive Evaluation
`33.1
`Inspection methods
`33.2 Usage simulations
`33.3
`Structured expert reviewing
`33.4 Modelling: The keystroke level model
`
`{l
`
`SCEA EL10_13,P_a e 8
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`SCEA Ex. 1013 Page 8
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`

`

`Glossary
`
`Solutions to Questions
`
`References
`
`Index
`
`
`
`SCEA Ex. 1013 Page 9
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`SCEA Ex. 1013 Page 9
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`

`

`
`
`What is HCI?
`
`.1 Technological change: Different design needs
`.2 The challenge of HCI
`8
`.3 The goals of HCI
`l4
`.4 HCI and its evolution
`
`16
`
`5
`
`.5 The importance of HCI: Productivity
`.6 When things go wrong 23
`Key points 26
`Further reading 26
`
`19
`
`Aims and objectives
`
`to introduce you to the study of Human—
`The aim of this chapter is
`Computer Interaction [HCI], so that after studying it you are able to:
`
`0
`
`o
`
`0
`
`0
`
`0
`
`0
`
`describe what HCI is,
`
`discuss and argue about why HCl is important with reference to the
`way in which technology has developed during the past thirty years,
`describe some of the goals of HCI that are concerned with improving
`productivity and designing safe systems,
`describe how HCI has evolved to ensure that the needs of different
`
`kinds of users are taken into account in computer system design,
`outline the quantifiable benefits of good HCI design for both individuals
`and organizations,
`describe the role of HCI in the design of safety critical systems.
`
`SCEA EX. 1013 Page 10
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`SCEA Ex. 1013 Page 10
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`

`

`During the past twenty years technology has advanced to such an extent
`that almost everyone comes into contact with computers in one way or
`other. Unlike in the early days of computing, when only highly skilled
`technical people used computers, nowadays the range of knowledge and
`experience of different users is very broad. So, it is important that the way in
`which people interact with computers is intuitive and clear. However,
`designing appropriate HCI
`is not always straightfonrvard, as the many
`poorly designed computer systems testify. One of the challenges of HCI
`design is to keep abreast of technological developments and to ensure that
`they are harnessed for maximum human benefit.
`The main reason why many people in the business community are
`interested in finding out about HCI is because they want to increase the
`efficiency of their staff and, hence, make more money. Another important
`factor is safety; some kinds of computer systems can endanger life if they do
`not have good HCI.
`
`
`
`When computers first appeared on the commercial scene in the 19505, they were
`extremely difficult to use, cumbersome and at times unpredictable. There were a
`number of reasons for this:
`
`a They were very large and expensive machines, so that by comparison human
`labour (that is, ‘people time‘) was an inexpensive resource.
`They were used only by technical specialists — scientists and engineers — who
`were familiar with the intricacies of off-line programming using punch cards.
`Little was known about how to make them easier to use.
`
`o
`
`0
`
`None of these conditions holds today: computers have become much less expensive,
`users come from every walk of life, and we understand a great deal more about how
`to fit the machines to people‘s needs and their work.
`Dramatic decreases in the cost of computing resources have resulted from new
`technological advances, the most significant being the development of the silicon
`chip. The ability not only to miniaturize circuits but also to pack large numbers of
`them on to tiny, individual chips paved the way for the development of powerful
`computers with large storage capacity. In less than thirty years computers changed
`from being huge machines housed in large. air-conditioned rooms to much smaller
`machines, including some that can easily be carried around by children. Computers
`have also become more reliable and today’s machines do not suffer from overheating
`like their ancestors. Computing has entered a new era and is becoming ubiquitous.
`
`SCEA EX. 1013 Page 11
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`SCEA Ex. 1013 Page 11
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`

`

`that almost everyone comes into contact with computers in one way or
`other. Unlike in the early days of computing, when only highly skilled
`technical people used computers, nowadays the range of knowledge and
`experience of different users is very broad. So, it is important that the way in
`which people interact with computers is intuitive and clear. However,
`designing appropriate HCl
`is not always straightforward, as the many
`poorly designed computer systems testify. One of the challenges of HCl
`design is to keep abreast of technological developments and to ensure that
`they are harnessed for maximum human benefit.
`The main reason why many people in the business community are
`interested in finding out about HCl is because they want to increase the
`efficiency of their staff and, hence, make more money. Another important
`factor is safety; some kinds of computer systems can endanger life if they do
`not have good HCl.
`
`
`
`When computers first appeared on the commercial scene in the 19505, they were
`extremely difficult to use, cumbersome and at times unpredictable. There were a
`number of reasons for this:
`
`a They were very large and expensive machines, so that by comparison human
`labour (that is, ‘people time’) was an inexpensive resource.
`I They were used only by technical specialists — scientists and engineers — who
`were familiar with the intricacies of off-line programming using punch cards.
`Little was known about how to make them easier to use.
`
`0
`
`None of these conditions holds today: computers have become much less expensive,
`users come from every walk of life, and we understand a great deal more about how
`to fit the machines to people‘s needs and their work.
`Dramatic decreases in the cost of computing resources have resulted from new
`technological advances, the most significant being the development of the silicon
`chip. The ability not only to miniaturize circuits but also to Pack large numbers of
`them on to tiny, individual chips paved the way for the development of powerful
`computers with large storage capacity. In less than thirty years computers changed
`from being huge machines housed in large, air-conditioned rooms to much smaller
`machines, including some that can easily be carried around by children. Computers
`have also become more reliable and today's machines do not suffer from overheating
`like their ancestors. Computing has entered a new era and is becoming ubiquitous.
`
`SCEA EX. 1013 Page 12
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`SCEA Ex. 1013 Page 12
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`

`

`experienced programmers being the only users, people from all walks of life e
`commerce, farming, education, retailing, defence, manufacturing and entertainment
`— began using computer systems.
`These changes in the technology have opened up a wide range of new
`possibilities for the way in which computers can be used. The sheer costliness and
`time required to run programs on the early machines dictated the kinds of
`commercial application in which computers could be used. Businesses such as
`banking and accounting, with large-scale record keeping activities, were the first to
`take up computing technology. Companies that were involved in activities with 'fast‘
`cycles, such as transaction processing for airlines and retailing, could not make use
`of these machines. They were not sufficiently fast or responsive, but this is not a
`problem with modern computers.
`Computers have also found a place in many private homes. in fact, such has
`been their pervasiveness that now just about everyone, young or old, able or
`disabled, skilled or unskilled, is using or is directly affected by computers in one way
`or another.
`
`rW-mwewwms
`
`i 1.1 g Technological change: different design needs
`
`For computers to be widely accepted and used effectively they need to be well
`designed. This is not to say that all systems have to be designed to accommodate
`everyone, but that computers should be designed for the needs and capabilities of
`the people for whom they are intended. Ultimately, users should not even have to
`think about the intricacies of how to use a computer. Just as knowledge of how the
`actual mechanics of steering an automobile is transmitted from the steering wheel to
`the wheels is of little concern to most motorists, so too should knowledge of the
`internal workings of a computer be of little consequence to its users. However, just as
`the shape and position of the steering wheel and its effect when turned has an
`enormous impact on the driver, so too will the design of the computer system have
`an effect on its user. The format of the input and the style of feedback affect the
`success with which any artefact is used.
`Donald Norman (1988, 1992), author of The Psychology of Everyday Things,
`and Turn Signals are the Facial Expressions of Automobiles, catalogues many
`examples of everyday things that do not present a clear and obvious image to their
`users. if you think about the complexity of most computer systems you can see that
`the potential for poorly designed l-ICI is very high. However, Norman identifies two
`key principles that help to ensure good HCl: visibility and affordance. Controls
`need to be visible, with good mapping with their effects, and their design should also
`suggest (that is, afford) their functionality. Box 1.1 contains more information about
`visibility and affordance.
`
`SCEA EX. 1013 Page 13
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`SCEA Ex. 1013 Page 13
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`

`

`In cars things are generally visible. There are good mappings between the controls
`and their effects, between the driver's goals and needs and the functions available.
`A control often has just one function. There is good feedback and the system is
`understandable.
`In general,
`the relationships between the user‘s goals,
`required actions and the results are sensible, meaningful and not arbitrary. With
`many video recorders, however, there is no visible structure. Mappings between
`controls and their effects are arbitrary, there is no correspondence between the
`user’s goals and the buttons and displays that make up the interface. Several of
`the controls have multiple functions. There is very poor feedback, so a user is
`often unsure whether the desired result has been obtained. In general, the system
`
`is not easily understandable.
`Norman (1992, p. 19) defines affordance as a ‘technical term that refers to
`the properties of objects , what sorts of operations and manipulations can be
`done to a particular object”. Doors, for example, afford opening, whereas a chair
`affords support. Affordances play a large part in the design of objects but what is
`important is ‘perceived affordance’ r what a person thinks can be done with the
`object. For example, does the design of the door suggest that it should be pushed
`open or pulled? Unfortunately, aesthetics sometimes conflict with good affordance
`and the appearance of the object takes precedence over its use.
`
`EXERCISE
`
`The management of British Rail were trying to decide which material to use for a
`partition on one of their platforms. Should it be glass or very thin plywood? Both
`were about the same cost. Thinking that glass would be the more attractive, they
`selected toughened glass. However, even toughened glass was not strong enough
`to deter the vandals in that area, and after replacing the smashed glass twice they
`eventually opted for the piywood. Although no stronger, the plywood remained
`intact but there were other problems. Can you think what they were? What kind of
`actions did the glass afford and what did the plywood afford?
`
`COMMENT
`
`Within a very short time the plywood was covered with all kinds of graffiti,
`but despite being thin it was not smashed. The glass afforded smashng and
`the plywood afforded drawing and writing. Section 13.7 discusses
`affordance in more detail and contains more examples.
`Visibility and affordance, therefore, are very important principles in HCI
`design. (See Norman (1988, 1992) for further examples.)
`
`
`|__—_—_—————f
`
`SCEA EX. 1013 Page 14
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`SCEA Ex. 1013 Page 14
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`

`

`They also need to consider the interaction that goes on between users and a
`computer system. During the technology explosion of the 19705 the notion of the
`user interface, also known as the Man—Machine Interface (MMI), became a
`general concern to both system designers and researchers. Moran defined this term
`as ‘those aspects of the system that the user comes in contact with’ (1981, p. 4),
`which in turn means ‘an input language for the user, an output language for the
`machine, and a protocol for interaction’ (Chi, 1985, p. 671).
`Computer companies became aware that if they could somehow improve the
`physical aspects of the user interface they would stand a better chance of being
`successful in the market-place. To exploit this new dimension, a greatly overused
`cliche evolved — calling a system 'user—friendly’. In practice, this often simply meant
`tidying up the screen displays to make them more aesthetically pleasing. While this was
`an improvement on earlier interfaces (which wasn't that difficult) , many companies —
`unfortunately— used the term simply as a marketing ploy, paying lip service to the real
`issues surrounding HCI. Most systems Were still not designed to match users’ needs and
`still required users to cope with what seemed more like 'user—hostile'
`Academic researchers, in contrast, were concerned about how the use of computers
`might enrich the work and personal lives of people. In particular, they focused on the
`capabilities and limitations of human users, that is, understanding the ‘people side' of
`the interaction with computer systems. At that time this primarily meant understanding
`people's psychological processes when interacting with computers. However, as the
`field began to develop it soon became clear that other aspects impinge on users and
`that these, too, should be included. For example, training issues, working practices,
`management and organizational issues and health hazards are all important factors
`contributing to the success or failure of using computer systems.
`The term human—computer interaction (HCI) was adopted in the mid-19805
`as a means of describing this new field of study. This term acknowledged that the
`focus of interest was broader than just the design of the interface and was concerned
`with all those aspects that relate to the interaction between users and computers.
`Also, unlike the term man—machine studies, it did not imply gender bias. Although
`there are still no currently agreed definitions of HCI,
`the following definition
`embodies the spirit at that time: ‘[a] set of processes, dialogues, and actions through
`which a human user employs and interacts with a computer' (Baecker and Buxton,
`1987, p. 40). A more recent and broader characterization is provided by the
`following definition: ‘human—computer interaction is a discipline concerned with
`the design, evaluation and implementation of interactive computing systems for
`human use and with the study of major phenomena surrounding them’
`SIGCHI, 1992, p. 6).
`
`Question 1.1
`
`What is the difference between the tenns ‘user interface” and ‘ human—computer
`interaction' ?
`
`SCEA EX. 1013 Page 15
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`SCEA Ex. 1013 Page 15
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`

`

`
`
`Input
`
`Input devices 212
`11.1
`11.2 A sample of Input Issues: Keyboards 214
`11.3 Pointing devIces 217
`1 1.4 Matching devIces wIth work 221
`11.5 Matching devices with users: Input for the disabled 224
`11.6 Matching devices with environments of use 227
`11.7 Developments in input 230
`Key points 235
`Further reading 236
`
`Aims and objectives
`
`The aim of this chapter is to introduce you to various kinds of input devices
`and discuss some of the factors that need to be considered when selecting
`an input device. After studying this chapter you should be able to:
`
`I
`
`0
`
`0
`
`discuss the properties of different input devices in relation to different
`design needs,
`apply your understanding of user, work and environment characteristics
`to select appropriate input devices and techniques,
`envision the design impacts of emerging input technologies.
`
`Overview
`
`Environmental conditions, safety hazards, the variation in tasks and their
`relationship to other work all have to be taken into account when selecting
`
`SCEA EX. 1013 Page 16
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`SCEA Ex. 1013 Page 16
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`characteristics like culture and gender. Knowing the scope of different
`kinds of devices is important too, because ultimately you have to match the
`technology with the user and work needs, not forgetting the work
`environment.
`
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`Input devices
`
`Input is concerned with recording and entering data into the computer system and
`issuing instructions to the computer.
`In order to interact with computer systems
`effectively, users must be able to communicate their intentions in such a way that the
`machine can interpret them. Therefore, we can define an input device as: a device
`that, together with appropriate software, transforms information from the user into
`data that a computer application can process.
`One of the key aims in selecting an input device and deciding how it will be
`used to control events in the system is to help users to carry out their work safely,
`effectively, efficiently and, if possible, to also make it enjoyable. The choice of input
`device should contribute as positively as possible to the usability of the system. In
`general, the most appropriate input device will be the one that:
`
`0
`
`0 matches the physiological and psychological characteristics of users,
`training and their expertise. For example, older adults may be hampered by
`conditions such as arthritis and may be unable to type; inexperienced users may
`be unfamiliar with keyboard layout.
`is appropriate for the tasks that are to be performed. For example, a drawing task
`requires an input device that allows continuous movement; selecting an option
`from a list requires an input device that permits discrete movement.
`is suitable for the intended work and environment. For example, speech input is
`useful where there is no surface on which to put a keyboard but is unsuitable in
`noisy conditions; automatic scanning is suitable if there is a large amount of data
`to be gathered.
`
`0
`
`Frequently the demands on the input device are conflicting, and no single optimal
`device can be identified: trade-offs usually have to be made between desirable and
`undesirable features in any given situation. Furthermore, many systems will use two
`or more input devices together, such as a keyboard and a mouse, so the devices
`must be complementary and well coordinated. This means that not only must an
`
`SCEA EX. 1013 Page 17
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`SCEA Ex. 1013 Page 17
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`

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`'Dam these hooves! I hit the wrong switch again!
`Who designs these instrument panels, raccoons?’
`
`(© 1986 United Feature Syndicate, Inc. Reprinted by permission.)
`
`input device be easy to use and the form of input be straightforward, there must also
`be adequate and appropriate system feedback (Norman, 1988) to guide, reassure,
`inform and, if necessary, correct users’ errors. This feedback can take various forms.
`It can be a visual display on a screen: a piece of text appears, an icon expands into a
`window, a cursor moves across the screen or a complete change of screen
`presentation occurs. It can be auditory: an alarm warning, a spoken comment or
`some other audible clue such as the sound of keys clicking when hit. It can be tactile:
`the feel of a button being depressed, or a change in pressure, such as ‘occurs when
`using a joystick. in many cases feedback from input can be a combination of visual,
`auditory and tactile responses. For example, when selecting an icon on a screen, the
`tactile feedback from the mouse button or function keys will
`tell users that they
`instructed the system to activate the icon. Simultaneously, visual feedback will show
`the icon changing shape on the screen. This is coordinated with the sound of the
`button clicking or the feel of the key resisting further pressure. in this chapter the
`various types of device are discussed in terms of their common characteristics and
`
`the factors that need to be considered when selecting an input device. In Chapter 12
`we return to the issue of feedback.
`
`SCEA EX. 1013 Page 18
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`SCEA Ex. 1013 Page 18
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`

`

`
`
`Figure 11.5 Touch screen (photographed in Milton Keynes central library).
`
`Touch screens
`
`Touch displays allow the user to input information into the computer simply by
`touching an appropriate part of the screen or a touch—sensitive pad near to the
`screen. In this way the screen of the computer becomes a bidirectional instrument in
`that it both receives information from a user and displays output from a system. Using
`appropriate software, different parts of a screen can represent different responses as
`different displays are presented to a user. For example, a system giving directions to
`visitors at a large exhibition may first present an overview of the exhibition layout in
`the form of a general map. A user may then be requested to touch the hall that he
`wishes to visit and the system will present a list of exhibits. Having selected the
`exhibit of his choice by touching it, the user may then be presented with a more
`detailed map of the chosen hall.
`The advantages of touch screens, as in Figure 11.5, are that they are easy to
`learn require no extra workspace, have no moving parts and are durable. They can
`provide a very direct interaction. Ease of learning makes them ideal for domains in
`which use by a particufar user may occur only once or twice, and users cannot be
`expected to spend time learning to use the system. (in Chapters 21 and 22 you will
`he introduced to the Eurochange system in which a touch screen is used) However,
`some less favourable reports claim lack of precision high error rates, arm fatigue
`from reaching to the screen, fingers obscuring detail on the screen and screen
`smudging. A survey by Muratore (1987)
`implied that of various cursor control
`devices studied, touch screen was the fastest but least accurate. Problems with arm
`fatigue and fingers obscuring the screen can be eased by the use of a remote off-
`screen touch pad, which can be positioned horizontally. In general, touch screens
`are thought to be good for large targets and untrained users, but inappropriate for
`frequent high resolution tasks or expert users. For recent developments in touch
`screens, see Section 11.7.
`
`SCEA EX. 1013 Page 19
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`SCEA Ex. 1013 Page 19
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`i
`
`fferingthe mostcomprehensiveaccountofthe multi—
`disciplinary field of HCl, this book illustrates-the powerful
`
`E NY PREECE
`N _
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`benefits of a user-oriented approach to the design of modern
`computer systems. It balanCes the technical and cognitive issues
`required for understanding the subtle interplay between people and
`computers, particularlyIn emerging fields like multimedia, virtual
`environments andcomputer supported cooperative work(CSCW).
`..
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`Y’yONNE ROGERS
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`0 DAVID BENYON
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`DONALD NORMAN
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`:DEBOAKAH HIx
`ROY KAL‘AWSKY
`MARILYN MANTEI
`t- TOM MORAN
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`BRIAN SHACKEL
`BEN SHNEIDERMAN
`BILL VERPIANK
`TERRY WINooRAI)
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`'
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`Human-Computer Interaction is flexibly structured to allow a variety
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`The book has been developed from successful modules offered by the
`UK Open University team chaired by Jenny Preece. ljer co-authors are
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`University of Guelph, Canada
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`SCEA EX. 1013 Page 20 _
`
`SCEA Ex. 1013 Page 20
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`