Human Capabilities: Mental Models CS352

Announcements Project – your users: due next Wed. 7/7 Quiz #3 (human capabilities) next Tue. 2

Hints: Team Process Improvement List risks and what you’ll do if they materialize. Agree on a process for working out disagreements in direction. –We should use a web interface! No, we should use portable bar-code readers! –eg: votes? eg: quality data from CogTool? eg: joint visits to office hours? Do a post-mortem after every hand-in or grade received –What went right in our process? Data, not finger-pointing: “we got an A-”. –What went wrong in our process? Data, not finger-pointing: “we had to pull an all-nighter because we started too late” –What will we do differently from now on? –Write it down and revisit next time.

Mental Models

Mental Models = How to use the system (and how the system works). Users build these in their heads. Developed over time. –Not always correct (and usually not complete). Thermostat example. –Why do users build these? Rote mem is hard, explained-by memory easier. Mental model is an explanation. –If user’s mental model is correct, will have an easier time using the system.

How to help user’s mental model be correct Remember Norman’s 2 Gulfs? 1Useful feedback in response to inputs (Evaluation). 2Context-sensitive devices for guidance (Execution). 3Ways of interacting with UI consistent with underlying workings (Eval+Exec). Activity: sketch a thermostat UI idea that does 1, 2, or 3.

How people do things: the 7 stages of an action Norman, at a conf in Italy. –Speaker needed to show film, had trouble threading it into projector. –Many people cam up to help, none succeeded. –Finally technical was called, who quickly threaded it correctly. Q: Why so hard? A: Structure of an action as relate to the Gulfs.

The 7 stages 1=goal. 2,3,4=execution. 5,6,7=evaluation

The 7 stages (cont) 1 goal: “what” we want to do. –Example. 2. execution intention (from what to how but top-level without details) –Example. 3. execution: sequence of actions. –Example. 4. execution: physicall do them (to objects in the world) –Example.

The 7 stages (cont.) 5. evaluation: perceiving (senses) what the world did in response (with our eyes, etc.) –Example. 6. evaluation: interpreting (brain) the perception. –Example. 7. evaluation: comparison of interpretation with goal. –Example.

The 7 stages (cont.) Gulf of Execution. –How to get from 1 to 2, 2 to 3, or 3 to 4. –Example

The 7 stages (cont.) Gulf of Evaluation. –How to get to 5 at all, 5 to 6, 6 to 7. –Example

The 7 stages as design aids To find problems, apply these to any task in a UI:How easily can determine... –1. Goal:...the purpose of the device/feature? –2. Exec:... what actions are possible? –3. Exec:...the mapping from intention to specific physical movements? –4. Exec:...how to actually perform the action? –5. Eval:...what state the system is in? –6. Eval:...what “that (feedback in UI)” means? –7. Eval: if system is in desired state?

Activity In pairs (cell phone owner, other) –Cell phone owner “drives” (no thinking, just hit keys when told to). –Other “thinks” (no access, just tell driver what to do). Task: –Make ALL display dimming go away. It should never dim at all under any circumstances. Ask the 7 questions at each stage. Write down problems you experience and the step you are at in the 7 stages.

To find solutions Consider these remedies. –Visibility: to reveal state (5), show what actions available (2). –Good mappings revealing: relationships between actions and results (2), controls and effects (3), system state and what is visible (6, 7) –Feedback every action provides immediate feedback of results (5,6,7)