Human Capabilities: Mental Models

1. Human Capabilities:Mental Models CS352

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

3. 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.

4. Mental Models http://www.youtube.com/watch?v=T2EIx9rBy78

5. 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.

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

7. 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.

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

9. 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.

10. 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.

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

12. The 7 stages (cont.) • Gulf of Evaluation. • How to get to 5 at all, 5 to 6, 6 to 7. • Example. 1 7 6 5

13. 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?

14. 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.

15. 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)