Einführung in die Kognitive Ergonomie

Transcription

1 185 Vorlesung 10, den 20. Januar Vorlesung 10, den 20. Januar 2000 Donnerstag, den 20. Januar 2000 Einführung in die Kognitive Ergonomie Wintersemester 1999/ Usability Principles (continued) (See Slides from Class 9) 2. Mental Models Revisited 3. Using Design Guidelines 4. The Usability Engineering Lifecycle 5. Developing User Profiles 6. Contextual Task Analysis WWW-Seite: Guidelines Concerning Command Names Guidelines Concerning Naming 186 Poor Improved Hierarchicalness Go Move forward Back Move backward Congruence Add Insert Kill Delete Specificity Change Replace Directory Search Familiarity Extract Delete Transmit Send Grammatical consistency Print Print Directory Search Distinctiveness Sen(d) Send Sea(rch) Find Sel(ect) Choose Mayhew, D. J. (1992). Principles and guidelines in software user-interface design. Englewood Cliffs, NJ: Prentice Hall.

2 187 Mental Models Revisited Mental Models Revisited The Role of Mental Models Objects Tasks Methods Objects Tasks Methods Designer, Design Model User, Mental Model Definitions of "Mental Model" 188 What is a mental model? Narrow definition A set of beliefs about s (perhaps unobservable) structure How works Broader definition Also, beliefs about What tasks can perform with What methods can use to perform these tasks

3 189 The Usability Engineering Lifecycle The Usability Engineering Lifecycle Overview of the Entire Lifecycle Mayhew, D. J. (1999). The usability engineering lifecycle: A practitioner s handbook for user interface design. San Francisco: Morgan Kaufmann. Comments on Lifecycle Models 190 Many models of the software development lifecycle have been formulated The textbook gives another example of such a model Mayhew s model is especially useful in that it focuses on activities that concern usability The other activities involved in software engineering must of course also be kept in mind

4 191 The Usability Engineering Lifecycle The Requirements Analysis Phase Developing User Profiles Procedures 192 Best procedure Distinguish user categories = Develop questionnaire Administer questionnaire to large sample of users from all categories Formulate conclusions about each user category Today s procedure Select a few sample questions Guess what the answers might be List a few points about each user category

5 193 Developing User Profiles Welche Benutzergruppen sind zu analysieren? Mögliche Kategorien Erwachsene, die zuhause privat verwenden wollen aber noch keine -erfahrung haben Entsprechende Benutzer, die bereits -erfahrung haben Erwachsene, die außerhalb des Büros privat und beruflich verwenden (zuhause, auf Reisen) Kinder, die mit anderen Kindern s austauschen wollen Very Short User Questionnaire (1) How old are you? < > Do you enjoy learning about computers? No Sometimes, depends on application Yes 3. What s the most complex type of system that you ve used regularly? None Simpler than Same complexity as More sophisticated than

6 195 Developing User Profiles Very Short User Questionnaire (2) 4. How many computer applications have you used? None > 10, but I have no programming skills > 10 and I have programming skills 5. What is your highest level of education? Grundschule Haupt- oder Realschule Gymnasium Hochschule Category: Profile of a User Category (1) 196 Age < > 60 Computer enjoyment? No Sometimes Yes system complexity None < = > Number of applications used None > 10, no progr. > 10, + progr. Indicate the answers you would expect from users in this category by (a) writing in percentages or (b) just checking the most likely answer

7 197 Developing User Profiles Profile of a User Category (2) Category: Age < > 60 Computer enjoyment? No Sometimes Yes system complexity None < = > Number of applications used None > 10, no progr. > 10, + progr. Importance of Usability Requirements 198 Group Ease of learning Speed of use Errors Mental load Enjoyment Functionality Adult beginners Adults with experience Blank = "not important"; "+" = "important"; "++" = "very important"

8 199 Contextual Task Analysis Contextual Task Analysis Procedures Best procedure Review requirements specifications Meet with project team members and user representatives Select key actors and use cases for detailed analysis Observe and interview users in the natural context of system use Document the work environment analysis Construct task scenarios Document the task analysis Identify all basic user tasks Specify a user task organization model, with the help of users Today s procedure = Meet with project team members = Think back to our relevant experience Note a few key points about a couple of the environments Construct one example scenario Note features of one key scenario Which Actors and Use Cases? 200 Actor 1. Internet-Neuling, der privat surfen und schreiben möchte 2. Versierter T-Online-Benutzer, der regelmäßig mit Freunden und Bekannten korrespondiert Use case versucht zuhause, mit, zum ersten Mal im Leben, eine zu schreiben schreibt abends , wobei er abwechselnd auch im Internet surft und sich zwischendurch mit der Familie unterhält 3.

9 201 Contextual Task Analysis Features of the Work Environment (1) Actor and Use Case: Aspect of Environment Key features here Physical aspects Noise level Distractions Sociocultural aspects Motivation to perform task Support from other persons Task-related aspects Amount of work to be done Time pressure Importance of good performance Reading Assignment for Class 11 Reading Assignment for Class Chapter 5 - The Design Process Overview 5.1 Introduction, p The Software Life Cycle, p. 179 Many of these ideas may be familiar from previous courses Especially important here are the comments about the role of usability analyses in the traditional software life cycle 5.3 Using Design Rules, p. 190 We discuss some design guidelines in depth in Class 10 The complete text of Smith and Mosier s classic report on design guidelines (1986) is available in a PDF file via the course Web site [End], p. 199

10 203 Design Project Assignment for Class Design Project Assignment for Class Applying Design Guidelines Retrieve the classic Smith-Mosier design guidelines from the course web site Find at least two guidelines that appear to be violated in if possible, concerning very different aspects of For each such guideline, write a note to the designers of the following form: The text of the Guideline X is as follows: [You can copy the text from the file in the Acrobat Reader] The guideline is violated in the following way in : [State specifically which aspect(s) of violate the guideline, perhaps using a screen shot] In my view, this is a moderately/very serious violation, because it can have the following consequences for the user: [Describe any errors, misunderstandings, inefficiencies, or other problems that you think could be caused by the violation]