Human Computer Interaction - Essay Example

HUMAN COMPUTER INTERACTION [The primary s) of this paper] [The College which grants your degree] Table of Contents Table of Contents 2 INTRODUCTION 6 TASK ANALYSIS 7 Summary 7 Benefits 7 Uses of Task Analysis 7 Designing products, processes and systems 7 Predict difficulties in product use, predict performance of the user 7 Evaluate systems against usability and/or functional requirements 7 Understand the difficulties of using existing products 7 Development of training manuals for products 7 Determine critical information that needs to be displayed 7 Determine information required on screen or in manuals during different aspects of product use 7 Predict possible difficulties in using different design alternatives 7 Provide a vehicle for communication between developers and others involved in the development process 7 Provide the basic information for a systems based approach to design 7 Design operating procedures 7 Allocate activities between people and machines 8 Types of task analysis 8 * Indicates iteration 8 Indicates selection 8 ----- Indicates absence of an action 8 When to use task analysis 9 Task decomposition 9 Task Analysis of current scenario 10 USER INTERFACE 10 Usability 10 ERGONOMICS AND DESIGN 12 Solutions by Design 13 Applications 13 Evaluation 14 Interviews with Principle Informants 14 Field observation of the system in use 14 Construction of day-in-the-life scenarios 14 May have number of functions during development - 15 Assessing performance of existing system (e.g. input to requirements for new release/system) 16 Assessing performance of prototype (input to continuing design) 16 Assessing performance of new system (input to redesign, training) 16 Mixing observation and reports 16 1, Usage statistics (e.g. click stream analysis on Web servers) 16 2, Help desk statistics/descriptions 16 3, User groups, bulletin boards 16 4, Affective tangibles" - detect frustration and context/problem 16 Analytic techniques 16 Informal = implicit representations of system (e.g. in mind of practitioner; 16 Expert's opinion) 16 Formal = explicit model of system (e.g. specified in notation) 16 A, detailed analysis of user-system interaction to evaluation to predict performance (KLM, GOMS, cognitive walkthrough) 16 Expert assessment 16 HCI expert systematically "walks through" the design, as if s/he were a user 16 Specialist evaluates system performance on basis of expected behavior of users 16 Will employ some analytic technique 16 Pro: 16 Fast assessment 16 Coherent recommendations for changes 16 Cons: 16 How good is the expert 16 Knowledge of users & domain 16 B, Heuristic evaluation 16 "Do-it-yourself" or "discount" specialist walkthrough 16 Goal: find the usability problems in the design so that they can be "weeded out" as part of an iterative design process. 16 How: Group of evaluators examines the interface and judges its compliance with recognized usability principles (the "heuristics"). 16 Rate the "severity" of problem and plan how to fix them. 16 The Heuristics (1) 17 Visibility of system status 17 Match between system and the real world 17 User control and freedom 17 Consistency and standards 17 Error prevention 17 The Heuristics (2) 17 Recognition rather than recall 17 Flexibility and efficiency of use 17 Aesthetic and minimalist design 17 Help users recognize, diagnose, and recover from errors 17 Help and documentation 17 Severity ratings 17 Derive a rating for the problem based on frequency, impact and severity. 17 Can be used to set priorities (fix most serious problems first), allocate resources and provide a rough estimate of the need for additional usability efforts. 17 Pros and Cons: Heuristic Evaluation 17 Pros 17 Detects both major (42%) and minor (32%) problems in UI 17 More effective than single specialist 17 Can be used on designs 17 "Realistic" approach 17 "Severity rating" helps to set priorities 17 Cons 17 Groups can develop their own bias 17 Doing it properly is not that cheap 17 New technologies (Web, Multimedia, Virtual Reality) may have specific problems not covered by The Heuristics 17 Choice of technique depends upon context such as, 17 Stage of system development 17 Resources available 17 Time 18 Evaluators 18 Users 18 Laboratory/equipment/facilities 18 Acceptability of intrusion on users, etc. 18 Type of output required 18 Precision / reliability 18 Diagnostic information 18 Level of behavior of interest 18 References 20 Alan Dix, Janet Finlay, Gregory D. Abowd, and Russell Beale (2003): Human-Computer Interaction. 3rd Edition. Prentice Hall, 2003. http://hcibook.com/e3/ ISBN 0-13046-109-1 20 Ben Shneiderman: Designing the User Interface. Strategies for Effective Human-Computer Interaction. 3. ed. Addison Wesley Longman, Reading 1998 ISBN 0-201-69497-2 20 Brad A. Myers: A brief history of human-computer interaction technology. Interactions 5(2):44-54, 1998, ISSN 1072-5520 ACM Press. http://doi.acm.org/10.1145/274430.274436 20 Bruce Tognazzini: Tog on Interface. Addison-Wesley, Reading 1991 ISBN 0-201-60842-1 20 Donald A. Norman: The Psychology of Everyday Things. Basic Books, New York 1988 ISBN 0-465-06709-3 20 Engineering Psychology and Human Performance - Wickens and Hollands - Discusses memory, attention, decision-making, stress and human error, among other topics. 20 Ergonomics for Beginners - Jan Dul and Bernard Weerdmeester - A classic introduction on ergonomics - Original title: Vademecum Ergonomie (Dutch) -published and updated since 1960's. 20 Jakob Nielsen: Usability Engineering. Academic Press, Boston 1993 ISBN 0-12-518405-0 20 Jef Raskin: The humane interface. New directions for designing interactive systems. Addison-Wesley, Boston 2000 ISBN 0-201-37937-6 20 Julie A. Jacko and Andrew Sears (Eds.). (2003). Handbook for Human Computer Interaction. Mahwah: Lawrence Erlbaum & Associates. ISBN 0-8058-4468-6 20 Ronald M. Baecker, Jonathan Grudin, William A. S. Buxton, Saul Greenberg (1995): Readings in human-computer interaction. Toward the Year 2000. 2. ed. Morgan Kaufmann, San Francisco 1995 ISBN 1-558-60246-1 20 Shneiderman, B & Plaisant C (2005) Designing the User Interface Addison-WestleySutcliffe, A.G (1995) Human Computer Interface Macmillan 21 Stuart K. Card, Thomas P. Moran, Allen Newell: The Psychology of Human-Computer Interaction. Erlbaum, Hillsdale 1983 ISBN 0-89859-243-7 21 The Design of Everyday Things - Donald Norman - An entertaining user-centered critique of nearly every gadget out there (at the time it was published). 21 The Measure of Man & Woman - Henry Dreyfuss Associates - A human factors design manual. 21 William S. Bainbridge, ed. (2004): Berkshire Encyclopedia of Human-Computer Interaction. 2 volumes. Great Barrington, MA: Berkshire. http://www.berkshirehci.com. ISBN 0-9743091-2-5 21 INTRODUCTION This paper will discuss about the various stages involved in evaluating a User Interface design (also known as UI) for a system that will be used by University RACs (Research Award Coordinators). The paper will talk in detail of the various stages that are listed below. Task analysis - involves the various requirements of the system with respect to the UI Conceptualization & Design - involves various design techniques that can be used for UI design Evaluation - various techniques that are available for UI evaluation and the one that is well suited for the RAC system that is discussed in the paper Conclusion - the findings, observations that were obtained The paper talks about the UI design of a system for RACs, who do non-academic activities in assisting research students right from their induction to the college to their obtaining the PhDs. The will basically coordinate and liaise with different teams in the college, in preparing the various topics for which they admit students for their research work, list of professors who are available to supervise the research work in various areas, communication and coordination between college and the students, scheduling Interview for the applicants. Once the student is admitted to read for a research work at college, the RACs also assist in setup for stay, and computer and other miscellaneous requirements that will help students in successfully completing their research work. The UI design for the requirement discussed in the above passage calls for an intelligent, easy to use and a simple and user-friendly design, since the system will used by RACs who are not very much acquainted with the intricacies of Computers or software. They would rather prefer an interface that is non very intuitive. Some of the key concepts that will be discussed in the subsequent paragraphs are the task analysis, UI design techniques and their evaluation. Task analysis is the stage where the requirements of the system, from UI point of view will be explained in detail, analyzed, and the key criteria will be noted down. Once these criteria are identified, then the next stage involved in studying various UI design techniques that are available, and some of the most widely used ones. The paper will explain each of the techniques, and will identify the one that is most likely suited for the requirement given. The paper will provide sufficient justifications as to why a particular technique was chosen over the others and how it suits well for the RACs system design. In the concluding part, the paper will explain about the various observations that are made during the preparation of the paper and the techniques that is used for the UI design. TASK ANALYSIS Summary Task analysis analyses what a user is required to do in terms of actions and/or cognitive processes to achieve a task. A detailed task analysis can be conducted to understand the current system of User Interface design (also known as UI) used by University RACs (Research Award Coordinators) and the information flows within it. These information flows are important to the maintenance of the existing system and must be incorporated or substituted in any new system. Task analysis makes it possible to design and allocate tasks appropriately within the new system. The functions to be included within the system and the user interface can then be accurately specified. Benefits Task analysis provides structure for the concise, unambiguous description of the tasks performed to accomplish a goal, which then makes it easier to describe the user's actions, and to explore the implications of this for the design of the products. Task Analysis provides the foundational information about how people carry out tasks so that a wide variety of disciples can apply their expertise effectively to the design of the system. By focusing on the user's tasks the analyst builds a foundation of understanding of what the users do and what they need in order to do it successfully, rather than getting tied up in details of the tools and systems that they will use. By clearly identifying tasks and examining the relationships between them, this approach helps identify tasks that can be improved by a designer- simplified, or made safer or easier to learn. Uses of Task Analysis This list of ways that task analysis can be used as a source of ideas about how you can use the technique in your organization. Task analysis provides the information that is the basis for realizing the business benefits listed below. Designing products, processes and systems Predict difficulties in product use, predict performance of the user Evaluate systems against usability and/or functional requirements Understand the difficulties of using existing products Development of training manuals for products Determine critical information that needs to be displayed Determine information required on screen or in manuals during different aspects of product use Predict possible difficulties in using different design alternatives Provide a vehicle for communication between developers and others involved in the development process Provide the basic information for a systems based approach to design Design operating procedures Allocate activities between people and machines Types of task analysis 1, Hierarchical Task Analysis This analysis gives the graphical representation of the tasks involved in the system, high-level tasks are decomposed into constituent subtasks, operations & plans and it uses structure chart notation. In chart notation, tasks are ordered left to right, where, * Indicates iteration Indicates selection ----- Indicates absence of an action The HTA chart preparation involves three operations such as, Start analysis, Progress the analysis and three, Finalize the analysis. Start analysis - Area of work and main task are defined and the main task is further break down into 4-8 sub tasks and it is defined in terms of objective. Layered-plans are drawn for the sub tasks. Progress the analysis - Level of detail for the tasks has to be selected. Next the approach for this process has to be decided like depth-first, breadth-first or the combination of both and then hierarchical numbering convention has to be used. Finalize the analysis - Consistency in decompositions and numbering of tasks are checked and then user with good knowledge in the domain will be consulted. 2, Cognitive Task Analysis In this analysis with the help of cognitive theories, design process has been informed through application. Here some tasks and actions are cognitive, that has to be defined. Finally, internal representation has to be modeled and processing that occurs for the purpose of tasks that can be undertaken more effectively. Different techniques available for the CTA are, 1. Model Human Processor (MHP) 2. GOMS (Goals, Operators, Methods, and Selection rules) 3. Cognitive Complexity Theory (CCT) 4. Task Knowledge Structures (TKS) 5. Knowledge Analysis of Tasks (KAT) 3, Modeling Procedure knowledge In this analysis "how to do it" knowledge approach is followed, more focusing on mapping tasks to actions and finally "Goals, Operators, Methods and Selection rules" approach is followed. When to use task analysis Task analysis provides information that is used at the start of a User Interface design (also known as UI) for a system that will be used by University RACs (Research Award Coordinators); it provides a foundation for later design decisions. In designing a new User Interface design (also known as UI) for the system, task analysis can be used to sketch a proposed sequence of tasks and tool use for review by potential users and designers in order to reach consensus on the final design. The revised task analysis can be used as a communication tool across the design, documentation and training teams. In improving an existing system, task analysis can be used to document how the current system is used now in order to identify where there is room for improvement. In assessing training needs, task analysis can be used to document what is currently carried out, where current training is useful and where more training would be useful. Task Analysis provides the foundational information about how people carry out tasks using the new user interface design so that a wide variety of disciples can apply their expertise effectively to the design of the system. Task decomposition The aim of 'high level task decomposition' is to decompose the high level tasks and break them down into their constituent subtasks and operations. This will show an overall structure of the main user tasks. At a lower level, it may be desirable to show the task flows, decision processes and even screen layouts. The process of task decomposition is best represented as a structure chart (similar to that used in Hierarchical Task Analysis). This shows the sequencing of activities by ordering them from left to right. In order to break down a task, the question should be asked 'how is this task done' If a sub-task is identified at a lower level, it is possible to build up the structure by asking 'why is this done' The task decomposition can be carried out using the following stages: 1. Identify the task to be analyzed. 2. Break this down into between 4 and 8 subtasks. These subtasks should be specified in terms of objectives and, between them, should cover the whole area of interest of the system developed. 3. Draw the subtasks as a layered diagram ensuring that it is complete. 4. Decide upon the level of detail into which to decompose. Making a conscious decision at this stage will ensure that all the subtask decompositions are treated consistently. It may be decided that the decomposition should continue until flows are more easily represented as a task flow diagram. 5. Continue the decomposition process, ensuring that the decompositions and numbering are consistent. It is usually helpful to produce a written account as well as the decomposition diagram. 6. Present the analysis to someone else who has not been involved in the decomposition but who knows the tasks well enough to check for consistency. Task Analysis of current scenario 1. Gather student information 2. Sort out eligible student for research 3. Send them Invitations for research in specified areas. 4. Receive the replies and check the relevance of the areas with yours. 5. If area of research not under you forwarded the reply to the concerned RAC 6. Check for the availability of a lecturer having experience in the particular area. 7. Check for the availability of lecturer 8. Call the qualified candidates for interview 9. Send message for approval of research to the candidates who are eligible and affording 10. Organise external examiners and a viva for candidate who are about to complete their research. USER INTERFACE Usability The design of a user interface affects the amount of effort the user must expend to provide input for the system and to interpret the output of the system, and how much effort it takes to learn how to do this. Usability is the degree to which the design of a particular user interface takes into account the human psychology and physiology of the users, and makes the process of using the system effective, efficient and satisfying. Usability is mainly a characteristic of the user interface, but is also associated with the functionalities of the system. It describes how well a system can be used for its intended purpose by its target users with efficiency, effectiveness, and satisfaction, also taking into account the requirements from its context of use. These functionalities or features are not always parts of the user interface (e.g. are you able to reverse with your car or not), yet they are key elements in the usability of a product. In computer science and human-computer interaction, the user interface (of a computer program) refers to the graphical, textual and auditory information the program presents to the user, and the control sequences (such as keystrokes with the computer keyboard, movements of the computer mouse, and selections with the touch screen) the user employs to control the program. Most common types of user interfaces as of 2005 are, Graphical user interfaces, which accept input via devices such as computer keyboard and mouse and provide articulated graphical output on the computer monitor. There are at least two different principles widely used in GUI design: object-oriented interfaces and application oriented interfaces. Web-based user interfaces, which accept input and provide output by generating web pages, which are transported via the Internet and viewed by the user using a web browser program. User interfaces that are common in various fields outside desktop computing: Command-line interfaces, where the user provides the input by typing a command string with the computer keyboard and the system provide output by printing text on the computer monitor. Tactile interfaces supplement or replace other forms of output with haptic feedback methods and used in computerized simulators etc. Touch interfaces are graphical user interfaces using a touch screen display as a combined input and output device, and used in many types of industrial processes and machines, self-service machines etc. Other types of user interfaces: Attentive user interfaces manage the user attention deciding when to interrupt the user, the kind of warnings, and the level of detail of the messages presented to the user. Batch interfaces are non-interactive user interfaces, where the user specifies all the details of the batch job in advance to batch processing, and receives the output when all the processing is done. The computer does not prompt for further input after the processing has started. Crossing-based interfaces are graphical user interfaces in which the primary task consists in crossing boundaries instead of pointing. Gesture interfaces are graphical user interfaces, which accept input in a form of hand gestures, or mouse gestures sketched with a computer mouse or a stylus. Noncommand user interfaces, which observe the user to infer his needs and intentions, without requiring that he, formulate explicit commands. Reflexive user interfaces, where the users control and redefine the entire system via the user interface alone, for instance to change its command verbs. Typically, this is only possible with very rich graphic user interfaces. Tangible user interfaces, which place a greater emphasis on touch and physical environment or its element. ERGONOMICS AND DESIGN Ergonomics is the study of the human body at work. As a science, it has its roots in the industrial revolution. Time and motion studies were used to improve workers' performance. The success of Henry Ford's production line was a direct result of an understanding and respect for Ergonomics. Most of the data from which ergonomists based their studies grew from information gathered because of World War II. The need to clothe, transport and house troops, design airplane cockpits and gun stations and build efficient physical and technical training programs was the primary motivation. It has only been recently that designers could benefit from new databases and statistics and it is only recently that the results of bad ergonomics are showing up in large segments of the population, as RSIs (Repetitive Stress Injuries). The sea change occurring in industry because of the growth in information technology has changed the focus of Ergonomics from factories to offices and from machines that mimic the human body to machines that mimic the human mind. As a testament to the importance of ergonomics in today's world, the proliferation of web sites chock full of content should give you pause (while you do, stretch a little, close your eyes and take a few deep breaths...) These guides offer a lot of information, some of it conflicting, but application of the basic concepts will have a beneficial effect on the quality of your work and your life. Proper computing ergonomics is a combination of your physiology, your work environment and equipment, the nature of the task routines you regularly perform and the (good or bad) postural habits you have developed. It is very important to realize that, in the end, the only true judge of what is proper for you is you. Solutions by Design One of the key elements of good ergonomics is good environmental design. The way you lay out your workspace and how you interface with it has an immediate impact on both your productivity and your health. This is true for healthy workers, physically challenged workers and people already suffering from cumulative trauma disorders. Solutions may range from simple fixes such as adding height to the arm pads on your chair, installing an articulated keyboard platform and re-aiming lighting to the purchase of motorized adjustable work stations and body-conforming chairs that dynamically support you as you move. Domains The IEA divides ergonomics broadly into three domains: Physical ergonomics: deals with the human body's responses to physical and physiological loads. Relevant topics include manual materials handling, workstation layout, job demands, and risk factors such as repetition, vibration, force and awkward/static posture as they relate to musculoskeletal disorders (repetitive strain injury). Cognitive ergonomics, also known as engineering psychology, concerns mental processes such as perception, attention, cognition, motor control, and memory storage and retrieval as they affect interactions among humans and other elements of a system. Relevant topics include mental workload, vigilance, decision-making, skilled performance, human error, human-computer interaction, and training. Organizational ergonomics, or macro ergonomics, is concerned with the optimization of sociotechnical systems, including their organizational structures, policies, and processes. Relevant topics include shift work, scheduling, job satisfaction, motivational theory, supervision, teamwork, telework and ethics. Applications The more than twenty technical subgroups within the HFES (Human Factors and Ergonomics Society) indicate the range of applications for ergonomics. Human factors engineering continues to be successfully applied in the fields of aerospace, aging, health care, IT, product design, transportation, training, nuclear and virtual environments, among others. Kim Vicente, a University of Toronto Professor of Ergonomics, argues that the nuclear disaster in Chernobyl is attributable to plant designers not paying enough attention to human factors. "The operators were trained but the complexity of the reactor and the control panels nevertheless outstripped their ability to grasp what they were seeing [during the prelude to the disaster]." Human factors issues arise in simple systems and consumer products as well. Some examples include cellular telephones and other handheld devices that continue to shrink yet grow more complex (a phenomenon referred to as "creeping featurism"), millions of VCRs blinking "12:00" across the world because very few people can figure out how to program them, or alarm clocks that allow sleepy users to inadvertently turn off the alarm when they mean to hit 'snooze'. A user-centered design (UCD), also known as a systems approach or the usability engineering lifecycle aims to improve the user-system fit. Evaluation An assessment of the conformity between a work system's performance and its desired performance. Evaluation criteria performance must be determined before evaluation starts - this is part of evaluation plan. Performance is assessed in terms of, 1. Task outcome 2. User satisfaction 3. User cost Evaluation methods are of two types, 1, Empirical evaluation Observation-based evaluation 1. Observe users interacting with system 2. In usability lab - range from formal task-based assessment 3. In the field - long-term observation 4. Usually collect range of data There are three different empirical techniques to locate and analyze the ethical and social issues: Interviews with Principle Informants Field observation of the system in use Construction of day-in-the-life scenarios Interviews with Principle Informants Trainings are given in taking an expert's verbal description of a system and in turn, it is applied to determine the criteria the expert was using to describe the system and given training in constructing an interview protocol that led logically from basic issues to critical functions of the system. In addition, the ethical issues inherent in doing interviews (e.g. confidentiality, respect, informed consent) can be discussed. Based on that at least 3 and no more than 7 interviews will be conducted and there is chance for follow-up interviews as well. Designers, managers, lower level operators, clients and other important stack holders of the system will also be interviewed. Field Observation Training will be given in designing coding systems and taking field notes for careful, real time observation of the system in use. This observation is carried out to get a better feel for the chaos and complexity of actual system in use, as opposed to the description elicited in the interviews. Real-time observation is carried out for at least 3-5 hours. By this time on-line activity reports might already been prepared, and these may be used as part of the field observation. As part of this process, attempts are made to get as wide and varied set of observations as time permits. And collected information will be kept confidential. Day-In-The-Life Scenarios This technique, taken from human-computer interaction methods, involves taking the data from observations and interviews and using it to construct a "story-line" of a unit of the system over a unit of time. Observation-based data collection 1. Task measures: (task completion, time, errors) 2. System logs 3. Video recording - screen, keyboard, user and can be annotated 4. Audio recording (especially for "thinking aloud") 5. In the field: usually less structured & focused, general video recording User report-based evaluation 1. Users are requested to provide information about their usage of a system 2. Assessment without having to observe the system actually in use May have number of functions during development - Assessing performance of existing system (e.g. input to requirements for new release/system) Assessing performance of prototype (input to continuing design) Assessing performance of new system (input to redesign, training) Mixing observation and reports 1, Usage statistics (e.g. click stream analysis on Web servers) 2, Help desk statistics/descriptions 3, User groups, bulletin boards 4, Affective tangibles" - detect frustration and context/problem Analytic techniques Techniques generally intend to predict system performance and distinction between formal and informal analysis Informal = implicit representations of system (e.g. in mind of practitioner; Expert's opinion) Formal = explicit model of system (e.g. specified in notation) A, detailed analysis of user-system interaction to evaluation to predict performance (KLM, GOMS, cognitive walkthrough) Expert assessment HCI expert systematically "walks through" the design, as if s/he were a user Specialist evaluates system performance on basis of expected behavior of users Will employ some analytic technique Pro: Fast assessment Coherent recommendations for changes Cons: How good is the expert Knowledge of users & domain B, Heuristic evaluation "Do-it-yourself" or "discount" specialist walkthrough Goal: find the usability problems in the design so that they can be "weeded out" as part of an iterative design process. How: Group of evaluators examines the interface and judges its compliance with recognized usability principles (the "heuristics"). Rate the "severity" of problem and plan how to fix them. The Heuristics (1) Visibility of system status Match between system and the real world User control and freedom Consistency and standards Error prevention The Heuristics (2) Recognition rather than recall Flexibility and efficiency of use Aesthetic and minimalist design Help users recognize, diagnose, and recover from errors Help and documentation Severity ratings Derive a rating for the problem based on frequency, impact and severity. Can be used to set priorities (fix most serious problems first), allocate resources and provide a rough estimate of the need for additional usability efforts. Pros and Cons: Heuristic Evaluation Pros Detects both major (42%) and minor (32%) problems in UI More effective than single specialist Can be used on designs "Realistic" approach "Severity rating" helps to set priorities Cons Groups can develop their own bias Doing it properly is not that cheap New technologies (Web, Multimedia, Virtual Reality) may have specific problems not covered by The Heuristics Choice of technique depends upon context such as, Stage of system development Resources available Time Evaluators Users Laboratory/equipment/facilities Acceptability of intrusion on users, etc. Type of output required Precision / reliability Diagnostic information Level of behavior of interest Two activities go hand-in-hand in a majority of HCI research: modeling and evaluation. Modeling addresses, what you know about the user, and often their surrounding social and physical environment. A variety of existing models, such as the Human-Model Processor, and modeling techniques, such as Contextual Inquiry, address differing domains and levels of specificity. Models may be used to predict performance, organize field data, and describe potential interactions with a computer interface. The most basic distinction is between a quantitative or qualitative evaluation. In a quantitative evaluation, the purpose is to come up with some objective metric of human performance that can be used to compare interaction phenomena. This can be contrasted with a qualitative evaluation, in which the purpose is to derive deeper understanding of the human interaction experience. A typical example of a quantitative evaluation is the empirical user study, a controlled experiment in which some hypothesis about interaction is tested through direct measurement. A typical example of a qualitative evaluation is an open-ended interview with relevant users. The cognitive walkthrough is a technique for evaluating the design of a user interface, with special attention to how well the interface supports "exploratory learning," i.e., first-time use without formal training. The evaluation can be performed by the system's designers in the early stages of design, before empirical user testing is possible. Early versions of the walkthrough method relied on a detailed series of questions, to be answered on paper or electronic forms. This material presents a simpler method, founded in an understanding of the cognitive theory that describes user's interactions with a system. The material refines the method based on recent empirical and theoretical studies of exploratory learning with display-based interfaces. The strengths and limitations of the walkthrough method are considered, and it is placed into the context of a more complete design approach. One of the basic lessons learned in the area of HCI is that usability evaluation should start early in the design process, optimally in the stages of early prototyping. The earlier critical design flaws are detected, the greater the chance that they can and will be corrected. Empirical usability testing, still the most comprehensive evaluation technique, however, is expensive and requires at least a working prototype. Traditionally, it is used at the end of the design cycle, where changes to the interface can be costly and difficult to implement. Unfortunately, usability recommendations given at this time are therefore often ignored. The cognitive walkthrough was developed as an additional tool in usability engineering, to give design teams a chance to evaluate early mockups of designs quickly. It does not require a fully functioning prototype, or the involvement of users. Instead, it helps designers to take on a potential users perspective, and therefore to identify some of the problems that might arise in interactions with the system. References Alan Dix, Janet Finlay, Gregory D. Abowd, and Russell Beale (2003): Human-Computer Interaction. 3rd Edition. Prentice Hall, 2003. http://hcibook.com/e3/ ISBN 0-13046-109-1 Ben Shneiderman: Designing the User Interface. Strategies for Effective Human-Computer Interaction. 3. ed. Addison Wesley Longman, Reading 1998 ISBN 0-201-69497-2 Brad A. Myers: A brief history of human-computer interaction technology. Interactions 5(2):44-54, 1998, ISSN 1072-5520 ACM Press. http://doi.acm.org/10.1145/274430.274436 Bruce Tognazzini: Tog on Interface. Addison-Wesley, Reading 1991 ISBN 0-201-60842-1 Donald A. Norman: The Psychology of Everyday Things. Basic Books, New York 1988 ISBN 0-465-06709-3 Engineering Psychology and Human Performance - Wickens and Hollands - Discusses memory, attention, decision-making, stress and human error, among other topics. Ergonomics for Beginners - Jan Dul and Bernard Weerdmeester - A classic introduction on ergonomics - Original title: Vademecum Ergonomie (Dutch) -published and updated since 1960's. Jakob Nielsen: Usability Engineering. Academic Press, Boston 1993 ISBN 0-12-518405-0 Jef Raskin: The humane interface. New directions for designing interactive systems. Addison-Wesley, Boston 2000 ISBN 0-201-37937-6 Julie A. Jacko and Andrew Sears (Eds.). (2003). Handbook for Human Computer Interaction. Mahwah: Lawrence Erlbaum & Associates. ISBN 0-8058-4468-6 Ronald M. Baecker, Jonathan Grudin, William A. S. Buxton, Saul Greenberg (1995): Readings in human-computer interaction. Toward the Year 2000. 2. ed. Morgan Kaufmann, San Francisco 1995 ISBN 1-558-60246-1 Shneiderman, B & Plaisant C (2005) Designing the User Interface Addison-WestleySutcliffe, A.G (1995) Human Computer Interface Macmillan Stuart K. Card, Thomas P. Moran, Allen Newell: The Psychology of Human-Computer Interaction. Erlbaum, Hillsdale 1983 ISBN 0-89859-243-7 The Design of Everyday Things - Donald Norman - An entertaining user-centered critique of nearly every gadget out there (at the time it was published). The Measure of Man & Woman - Henry Dreyfuss Associates - A human factors design manual. William S. Bainbridge, ed. (2004): Berkshire Encyclopedia of Human-Computer Interaction. 2 volumes. Great Barrington, MA: Berkshire. http://www.berkshirehci.com. ISBN 0-9743091-2-5 Read More