Einführung in die Kognitive Ergonomie

Transcription

1 251 Vorlesung 12, den 3. Februar Vorlesung 12, den 3. Februar 2000 Donnerstag, den 3. Februar 2000 Einführung in die Kognitive Ergonomie Wintersemester 1999/ Semiformal Task Analysis: Further Comments 2. Usability Engineering: Examples and Hints 3. Design Rationale: A Brief Introduction 4. Ubiquitous and Wearable Computing: Two Examples WWW-Seite: Comments on the GOMS Model Simple Example of a GOMS Analysis 252 Goal: Set time / alarm Press and hold button "Time" / "Alarm" Goal: Set hour... if not already right Goal: Set minute... if not already right Release button Goal: Set hour / minute Optional: Press and hold button "Hour" / "Minute"... until correct number has almost appeared Press button "Hour" / "Minute" briefly... until correct number appears

2 253 Comments on the GOMS Model Some GOMS Terminology "G" stands for goals and subgoals that pursues while performing a task Operators are user actions that are not analysed further (in this particular analysis) A method for attaining a particular goal G is a sequence of goals and/or operators that can be pursued in order to achieve G A selection rule is a criterion of a given user for deciding between two or more possible methods to achieve a given goal What Are Models Like GOMS Good For? (1) 254 Specification of a design A design, which may not yet have been implemented, can be specified from the user s point of view Finding problems in a design Inefficiency To achieve certain goals, has to apply unnecessarily many or unnecessarily time-consuming operators Inconsistency In some cases, similar goals can only be achieved through dissimilar means Poor learnability The methods for attaining certain goals are hard to discover and/or to remember Susceptibility to errors Although errors are not part of the original focus of GOMS, the analysis may clarify where particular types of error can occur

3 255 Comments on the GOMS Model What Are Models Like GOMS Good For? (2) Basis for Quantitative Predictions Most frequently used criteria Execution time Transfer time I.e., how much time does require to learn Method B, once he s already learned the related Method A? Problems with quantitative predictions They are only valid given certain assumptions They require values for various parameters Usability Engineering: Examples and Hints Checklist: Measurement Operations 256 The following list from Whiteside, Bennett, and Holtzblatt (1988) can complement Tables 5.3 and 5.4 How will you be able to check whether a usability requirement has been met? 1. Ask to perform a specific task (benchmarking) 2. Monitor during free use (logging and/or observing) 3. Give a questionnaire 4. Interview 5. Survey users 6. Ask for critical incidents revealing successes or failures

4 257 Usability Engineering: Examples and Hints Attribute Initial use Infrequent use Learning rate Preference over Z Error recovery Initial evaluation Fear of seeming foolish Specification for Conferencing System Measuring Concept Measuring Method Worst Case Conferencing task No. of successful 1 2 interactions in 30 min. Task after 1 2 % of errors weeks disuse Task 1st vs. 2nd half score Questionnaire Ratio of scores Same score as Z Critical incident analysis Attitude questionnaire Questionnaire % incidents accounted for Semantic differential score Obstacles related to interface Equal to 50% Z better 2 halves equal Planned Best Level Case nd half better 0 errors "Much" better None prefer Z 10% 50% 100% 0 1 (somewhat 2 (highly (neutral) positive) positive) Many Few None Whiteside, J., Bennett, J., & Holtzblatt, K. (1988). Usability engineering: Our experience and evolution. In Helander, M. (Ed.), Handbook of human-computer interaction, pp Amsterdam: North-Holland. Design Rationale A Graphical Notation for IBIS 258 Example of the graphical IBIS notation Cf. Dix et al., pp ; and Conklin, J., & Yakemovic, K. C. B. (1991). A process-oriented approach to design rationale. Human-Computer Interaction, 6,

5 259 Design Rationale A Textual Notation for IBIS? During what part of the class should the results of the design project work be discussed? # At the end of the class # At the beginning of the class + Students who aren t doing a + Subsequent discussion can design project can leave refer back to students own early examples? Couldn t they simply + Students are maximally alert come later instead? - Students who aren t doing a # No design project would get + The duration of the bored discussion of student? How many students won t work is do a design project? unpredictable # About half + Having students + General experience come later is more with this type of unconventional than course allowing them to leave early Textual IBIS: Basic Schema 260? Question # Possible Answer 1... # Possible Answer 2 + Argument that supports Possible Answer 2 > Reference to literature in which this argument is presented Argument that speaks against Possible Answer 2 Argument that speaks against the above argument? More specific question that is raised by this argument # Possible answer to this specific question... *# Possible Answer 3 ["*" = "ultimately accepted as best answer"]...? Another question... Essentially this version of the original graphical IBIS notation was introduced in: Yakemovic, K. C. B. & Conklin, E. J. (1990). Report on a development project use of an issue-based information system. CSCW90,

6 261 Design Rationale Role of Textual IBIS in Practice Notations like IBIS are useful in real life There exist a lot of other specific notations for design rationale See Section 5.6 of the textbook Most of these are more complex than the textual form of IBIS But a lot of people use some notation like this when analyzing complex problems and making decisions Ubiquitous Computing: The "Digital Ink" Vision Digital Ink: Overview (1) 262 Everybody uses a pen. We carry them in our pockets and briefcases. Their beauty lies in the simplicity and immediacy with which they let us record a thought or phone number on a napkin or even the back of a hand.

7 263 Ubiquitous Computing: The "Digital Ink" Vision Digital Ink: Overview (2) Part design, part critique, Digital Ink is the re-assemblage of current and future technologies into a portable and socially familiar object. It s a sophisticated pen that allows people to take notes, sketch, and digitally save their physical data as they write. It strives to turn mobile computing on it s head by turning the computer display into a piece of paper and the keyboard and input device into the pen itself. It s designed so people can do things they normally do with any pen, but also store, fax, plan and correspond with others. Digital Ink: Overview (3) 264 Digital Ink has cellular components that allow any stored information to be sent to computers, printers and fax machines by simply pressing the pen s mode button and writing words like "send to" followed by an address, or "fax to" followed by a phone number. The interaction language of the pen might look somthing like this: Send to mfanzo@berlin.com ->

8 265 Ubiquitous Computing: The "Digital Ink" Vision Digital Ink: Overview (4) Writing "Send to" invokes the command. The "->" ends the command and sends the message. The transmission s status is displayed on the pen s elliptical LCD. Another feature of Digital Ink is its ability to understand the meaning of the basic shapes and symbols that it draws, as well as their relative positions. For example, the pen can understand a drawing of a calculator as a calculator. This capability allows a person to create hand-drawn tools and interfaces when they need them. A small digital "inkwell" connects to any computer and serves as home to Digital Ink. It also serves as the pen s recharging station and downloading port. The first working prototype is currently under construction, but we still have many challenges ahead. For example, today, a production version would be fairly power intensive, and there are still several interaction and technology issues to be addressed. We are collaborating with other organizations to address these issues. Digital Ink: Overview (5) 266

9 267 Wearable Computing: Nomadic Radio Wearable Computing: Nomadic Radio Wearing the Nomadic Radio Speakers Microphone Nitin Sawhney and Chris Schmandt (1999). Nomadic Radio: Scaleable and Contextual Notification for Wearable Audio Messaging. CHI99, Notification Scenario 268 Distinct signals chosen by

10 269 Wearable Computing: Nomadic Radio Nomadic Radio: Issues (1)? How can notify of incoming messages?? How can notification be made differentiated?? How can notification take into account s current situation?? How can learn from previous interactions with?? How can notifications be coordinated?? How can distracting interruptions be minimized? Nomadic Radio: Issues (2) 270? How can auditory feedback be effective?? How can an incoming message be summarized? # Voice cues # First few words # Speeding up of playback? How can disruption be minimized? # Increase latency for less important messages #...

11 271 Wearable Computing: Nomadic Radio Overview of Auditory Output Scaling of Incoming Messages 272 The conspicuousness of a message depends on s assumed interruptability

12 273 Wearable Computing: Nomadic Radio Determinants of Message Priority Dynamic Adaptation 274 Adaptation is based on s actions in response to messages

13 275 Wearable Computing: Nomadic Radio Evaluation Results Nature of study One user, 2 days Feedback from Auditory feedback was distracting to others But it did cue them to wait Indication of priority through distinct signals wasn t found very useful Suggestion: Integrate priority information into continuous ambient noise Voice Cues were appreciated The overall auditory scheme was found too complex Reading for Class 13 Reading for Class Chapter 15 - Out of the Glass Box 15.6 Gesture Recognition, p Computer Vision, p Ubiquitous Computing Applications Research, p Interfaces for Users with Special Needs, p Virtual Reality, p. 578 [End], p. 583

14 277 Reading for Class Homework for Class 13 (1) Suppose you had the job of designing a completely new version of that made use of the more innovative interaction techniques discussed in Chapter 15 (not necessarily only the techniques discussed in the reading for this week): Speech Non-speech sound Handwriting recognition Gesture recognition Computer vision Techniques associated with ubiquitous computing Techniques developed for users with special needs Virtual reality Techniques for information and data visualisation Homework for Class 13 (2) 278 What techniques would be most useful? How would their realization in look? Specifically, describe a scenario in which a user uses your new version of, explaining how the more novel interaction techniques are used If you don t manage to work out your ideas in detail, at least make a start by sketching the basic nature of the new version of We will continue discussing this broad question next week