CS160 Discussion Section 7 Midterm review David Sun March 13, 2007

Assignment Concerns

Contextual Inquiry Explain the model of interaction between designer and user in contextual inquiry and contrast it with interviewing

In contextual inquiry, the designer and user behave in a master-apprentice fashion, such that the designer learns about the user’s tasks in order to understand them. The user explains how he carries out his work as he performs them, in front of the designer, at the user’s workplace. On the other hand, an interview becomes a question-and-answer process such that the user ceases to perform and explain his ongoing work. Contextual Inquiry

(continued) (You should be able to describe the four principles of contextual inquiry, how the master-apprentice model differs from the interviewer-interviewee, expert-novice, and host-guest models, the importance of task analysis, as well as a solid understanding of how contextual inquiry relates to task analysis and iterative design.) Beyer & Holtzblatt reading:

Human Centered Design In Human-Centered Design, at what stages of the design process should the customer or representative users be involved?

Task analysis, usability testing using prototypes, and tracking use. (This question is vague. Each designer has a different conceptualization of the exact stages in the task-centered design process, and the boundaries between stages are somewhat blur.) (Know not only the stages in which users are involved, but also how they are involved at each stage). Human Centered Design

Human Model Processor Briefly explain what each of the 5 main parts of the human model processor does.

Human Model Processor Three interacting subsystems –Perceptual, motor, cognitive –Serial in action, parallel in recognition. Memory stores: –Working memory: visual image and auditory image store; finite storage, fast decay time, physical encoding. –Long-term memory: infinite storage, no decay, semantic encoding, knowledge is stored by associations. –Working memory = activated portions of long- term memory.

Recognition vs. Recall Why is recognition preferred over recall?

Recognition vs. Recall Recall requires the user to reproduce information from long term memory –the ease of which differs from user to user depending on how the information was originally encoded and stored. Recognition presentation of info provides knowledge that info has been seen before –easier because of cues to retrieval

Structural vs. Functional Models Contrast structural and functional models.

Structural vs. Functional Models A structural model explains what the system does independent of use (it’s a system centered model) functional model explains what the system does to assist a user’s task (it’s a user- centered model).

Metaphors List two (good) user interface metaphors

Metaphors Desktop metaphor: –Directories are like folders –Files are like sheets of paper –Windows are like ?: –Menus are like menus –Deleting is like putting in the trash –Running an application program is like opening the doc. –Copy to buffer and restore is like cut-and- paste

Metaphors Other plausible questions: –Describe some of the difficulties/issues associated with the use of metaphors in interface design. –Give examples of some bad interface metaphors…

Conceptual Models Other than from a metaphor, where else do conceptual models come from?

Conceptual Models Other existing systems, and social-cultural norms. (Make sure that you also understand how conceptual models are an improvement over metaphors, and the significance of composite metaphors.)

Lo-fi Prototyping Give two advantages of rapid prototyping.

Lo-fi Prototyping Less time spent in coding. Forces designers and users to focus on the big picture: design of metaphors and mental models to facilitate uncovering major usability problems at early stages of interface design. (There are several other advantages of rapid prototyping and you should be aware of them. You should also understand the relative strengths and weaknesses between lo-fi and hi-fi prototyping) Rettig: “Prototyping for Tiny Fingers”

Heuristic Evaluation Process What are some of the advantages of heuristic evaluation? How many testers is a reasonable number in a heuristic evaluation? Why?

Heuristic Evaluation Advantages: –Cheap no special labs or equipment needed the more careful you are, the better it gets –Fast on order of 1 day to apply standard usability testing may take a week –Easy to use can be taught in 2-4 hours Small set (3-5) of evaluators examine UI –independently check for compliance with usability principles (“heuristics”) –different evaluators will find different problems –evaluators only communicate afterwards findings are then aggregated Can perform on working UI or on sketches

Heuristic Evaluation Process Describe how to perform a heuristic evaluation.

How to Perform Evaluation At least two passes for each evaluator –first to get feel for flow and scope of system –second to focus on specific elements If system is walk-up-and-use or evaluators are domain experts, no assistance needed –otherwise might supply evaluators with scenarios Each evaluator produces list of problems –explain why with reference to heuristic or other information –be specific and list each problem separately

Results of Using HE (cont.) Single evaluator achieves poor results –only finds 35% of usability problems –5 evaluators find ~ 75% of usability problems –why not more evaluators???? 10? 20? adding evaluators costs more many evaluators won’t find many more problems

More Questions Explain briefly why personas are useful for design. Why is user-interface design based on iterative refinement, rather than detailed specification?

(continued) How should budget usability methods be combined with user studies? Give some advantages of the master- apprentice model for contextual inquiry over other kinds of user questioning.

(continued) Which of the following statements best describes contextual inquiry? Circle all that apply. –a) A way of mastering how to perform the users’ tasks –b) A way of uncovering usability problems in a prototype –c) A way of understanding the users’ needs and work practices

More tips Make sure that you are aware of the major developments in the history of Human- Computer Interaction, and the pioneers who were responsible for these advances. Know what are the main stages of the human centered design cycle. Be sure that you understand Nelson’s heuristics and practice applying them in analyzing an interface design (you should get plenty from your assignment)

Administrivia Wed 3/21 Midterm Tue 2/20 Section: –Run as last-minute Q&A session. –Bring your questions.