CS160 Discussion Section 7 Midterm review

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CS160 Discussion Section 7Midterm review

• David Sun
• March 13, 2007

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Assignment Concerns
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Contextual Inquiry

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

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Contextual Inquiry

• In contextual inquiry, the designer and user
  behave in a master-apprentice fashion, such that
  the designer learns about the users 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 users 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.

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(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 http//inst.eecs.berke
ley.edu/cs160/sp07/readings/f3_beyer_holtzblatt.p
df
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Human Centered Design

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

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Human Centered Design

• 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).

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Human Model Processor

• Briefly explain what each of the 5 main parts of
  the human model processor does.

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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.

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Recognition vs. Recall

• Why is recognition preferred over recall?

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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

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Structural vs. Functional Models

• Contrast structural and functional models.

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Structural vs. Functional Models

• A structural model explains what the system does
  independent of use (its a system centered model)
• functional model explains what the system does to
  assist a users task (its a user-centered model).

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Metaphors

• List two (good) user interface metaphors

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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

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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

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Conceptual Models

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

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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.)

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Lo-fi Prototyping

• Give two advantages of rapid prototyping.

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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
http//inst.eecs.berkeley.edu/cs160/sp07/reading
s/f17_rettig_prototyping.pdf
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Heuristic Evaluation Process

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

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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

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Heuristic Evaluation Process

• Describe how to perform a heuristic evaluation.

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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

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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 wont find many more problems

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More Questions

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

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(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.

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(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

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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 Nelsons heuristics
  and practice applying them in analyzing an
  interface design (you should get plenty from your
  assignment)

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Administrivia

• Wed 3/21 Midterm
• Tue 2/20 Section
• Run as last-minute QA session.
• Bring your questions.