User Interface Design and Ergonomics - National Open University of ...

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Nielsen and Molich used their own experience to identify nine general heuristics (see table, below), which, as they noted, are implicit or explicit in almost all the lists of guidelines that have been suggested for HCI. Then they developed a procedure for applying their heuristics. The procedure is based on the observation that no single evaluator will find every problem with an interface, and different evaluators will often find different problems. So the procedure for heuristic analysis is this: Have several evaluators use the nine heuristics to identify problems with the interface, analyzing either a prototype or a paper description of the design. Each evaluator should do the analysis alone. Then combine the problems identified by the individual evaluators into a single list. Combining the individual results might be done by a single usability expert, but it's often useful to do this as a group activity. Nielsen and Molich's Nine Heuristics Simple and natural dialog - Simple means no irrelevant or rarely used information. Natural means an order that matches the task. Speak the user's language - Use words and concepts from the user's world. Don't use system-specific engineering terms. Minimize user memory load - Don't make the user remember things from one action to the next. Leave information on the screen until it's not needed. Be consistent - Users should be able to learn an action sequence in one part of the system and apply it again to get similar results in other places. Provide feedback - Let users know what effect their actions have on the system. Provide clearly marked exits - If users get into part of the system that doesn't interest them, they should always be able to get out quickly without damaging anything. Provide shortcuts - Shortcuts can help experienced users avoid lengthy dialogs and informational messages that they don't need. Good error messages - Good error messages let the user know what the problem is and how to correct it. Prevent errors - Whenever you write an error message you should also ask, can this error be avoided? The procedure works. Nielsen and Molich have shown that the combined list of interface problems includes many more problems than any single evaluator would identify, and with just a few evaluators it includes most of the major problems with the interface. Major problems, here, are problems that confuse users or cause them to make errors. The list will also include less critical problems that only slow or inconvenience the user. How many evaluators are needed to make the analysis work? That depends on how knowledgeable the evaluators are. If the evaluators are experienced interface experts, then 3 to 5 evaluators can catch all of the "heuristically identifiable" major problems, and they can catch 75 percent of the total heuristically identifiable problems. (We'll explain what "heuristically identifiable" means in a moment.) These experts might be people who've worked in interface design and evaluation for several years, or who have several years of graduate training in the area. For evaluators who are also specialists in the 174
specific domain of the interface (for example, graphic interfaces, or voice interfaces, or automated teller interfaces), the same results can probably be achieved with 2 to 3 evaluators. On the other hand, if the evaluators have no interface training or expertise, it might take as many as 15 of them to find 75 percent of the problems; 5 of these novice evaluators might find only 50 percent of the problems. We need to caution here that when we say "all" or "75 percent" or "50 percent," we're talking only about "heuristically identifiable" problems. That is, problems with the interface that actually violate one of the nine heuristics. What's gained by combining several evaluators’ results is an increased assurance that if a problem can be identified with the heuristics, then it will be. But there may still be problems that the heuristics themselves miss. Those problems might show up with some other evaluation method, such as user testing or a more task-oriented analysis. Also, all the numbers are averages of past results, not promises. Your results will vary with the interface and with the evaluators. But even with these caveats, the take-home message is still very positive: Individual heuristic evaluations of an interface, performed by 3 to 5 people with some expertise in interface design, will locate a significant number of the major problems. To give you a better idea of how Nielsen and Molich's nine heuristics apply, one of the authors has done a heuristic evaluation of the Macintosh background printing controls. 4.0 CONCLUSION The concept of evaluation of user interface without the users was introduced in this unit. Users walkthrough, action analysis and heuristics analysis concepts was also discussed in greater detail while emphasis on the need for evaluation was also introduced. 5.0 SUMMARY The cognitive walkthrough is a formalized way of imagining people's thoughts and actions when they use an interface for the first time. Action analysis is an evaluation procedure that forces you to take a close look at the sequence of actions a user has to perform to complete a task with an interface. In this unit, we will distinguish between two flavors of action analysis. The formal approach to action analysis has been used to make accurate predictions of the time it takes a skilled user to complete tasks. Heuristics, also called guidelines, are general principles or rules of thumb that can guide design decisions. 6.0 TUTOR MARKED ASSIGNMENT a. Explain the term heuristics. b. Explain the Nielsen and Molichs heuristics. 175
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] NATIONAL OPEN UNIVERSITY OF NIGER
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National Open University of Nigeria
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Summary ...........................
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UNIT 3 - GRAPHICAL USER INTERFACE (
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Assignments File Tutor-Marked Assig
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2 DESIGN and DESIGNING GOOD USER IN
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need both the study unit you are wo
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CIT 711: USER INTERFACE DESIGN AND
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UNIT 1 FUNDAMENTALS OF USER INTERFA
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3.3 TYPES OF USER INTERFACES Curren
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3.5 USER INTERFACE MODALITIES AND M
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Table of Contents 1.0 Introduction
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3.1.1 DESIGNING A GOOD USER INTERFA
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widgets properly is to read and und
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Figure 1:- Showing that alignment o
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6.0 TUTOR MARKED ASSIGNMENT a. How
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A graphical user interface is a typ
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Operating System. It is easy for a
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A list of items from which to selec
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collaborative work. For example, sc
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MODULE 1 UNIT 4 HUMAN COMPUTER INTE
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3.3 DIFFERNCES WITH RELATED FIELDS
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window blinds to automobile braking
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Wickens, Christopher D., John D. Le
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The International Ergonomics Associ
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approach, the Gilbreths reduced the
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3.6 BENEFITS OF ERGONOMICS The thre
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Another key to reducing lumbar disc
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MODULE 2 - USER INTERFACE DESIGN TE
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methods include inspection methods,
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Determine time of each operation (b
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unable to understand new informatio
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M cones, or, misleadingly, green co
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Motor skill which is a learned seri
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MODULE 2 UNIT 2 UNDERSTANDING USERS
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The users of a system must be ident
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This example brings up an important
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whether you want to have a palette
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Task analysis which includes identi
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MODULE 2 UNIT 3 USER CENTERED DESIG
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or small body text is also hard to
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Introduction to User-centered desig
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organizations themselves. Interacti
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After thorough analysis using vario
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Interaction design which is the dis
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In human-computer interaction and c
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The preferred method for ensuring u
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3.4 ISO STANDARDS FOR USABILITY ISO
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In this unit, you have been introdu
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affect the way the command is execu
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• Guides the user via the predefi
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The term direct manipulation was in
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There are two important reasons for
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UNIT 1 PROTOTYPING Table of Content
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Figure 12: The iterative steps of p
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select print Figure 13: An interfac
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Ambler, S.W. & Constantine, L.L. (2
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3.2 LOW-FIDELITY PROTOTYPES Low-fid
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Figure 14:- Example of Sketching II
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Much more important for features th
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Page 126 and 127: • Encourage menu & forms style, r
Page 128 and 129: Another problem is that native widg
Page 130 and 131: interfaces, so that a realistic sim
Page 132 and 133: UNIT 3 INPUT AND OUTPUT MODELS Tabl
Page 134 and 135: Recall that perceptual fusion means
Page 136 and 137: 3.2 OUTPUT MODEL There are basicall
Page 138 and 139: directly-mapped pixel image will no
Page 140 and 141: Most stroke models also include som
Page 142 and 143: UNIT 4 MODEL VIEW-CONTROLLER (MVC)
Page 144 and 145: 3.3.2 AS A DESIGN PATTERN MVC enco
Page 146 and 147: The Views are XForms controls for s
Page 148 and 149: UNIT 5 LAYOUTS AND CONSTRAINTS Tabl
Page 150 and 151: 3.5 CONSTRAINTS Constraints are rel
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Page 154 and 155: MODULE 4 UNIT 1 TECHNIQUES FOR EVAL
Page 156 and 157: a. Card Sorting Card sorting is a w
Page 158 and 159: Rapid prototyping is a method used
Page 160 and 161: 3.2.1 THE USE OF PROTOTYPES It is o
Page 162 and 163: Dumas, J.S. and Redish, J.C. (1999)
Page 164 and 165: the users' respect for you as a pro
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Page 168 and 169: speed whenever the average load was
Page 170 and 171: Table 4:- Table: Average times for
Page 172 and 173: phases: list the actions, and then
Page 176 and 177: 7.0 REFERENCES AND FURTHER READING
Page 178 and 179: users. If you do not, you can be ba
Page 180 and 181: If you are led to develop more and
Page 182 and 183: It's very easy to shape the comment
Page 184 and 185: a. Analyzing the Bottom-Line Number
Page 186 and 187: you use. But then you need some way
Page 188 and 189: ecruit test users with more similar
Page 190 and 191: MODULE 4 UNIT 4 OTHER EVALUATION IS
Page 192 and 193: 3.2 CURRENT ISSUES CONCERNING EVALU
Page 194 and 195: 2.0 OBJECTIVES By the end this unit
Page 196 and 197: It provides a real focal point for
Page 198 and 199: 3.3.4 CONDUCTING THE TEST Having co
Page 200: The stages involved in usability te
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