Human Capabilities: Mental Models

1. Human Capabilities:Mental Models

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: try both quickly with user? 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.

3. Mental Models = How to use the system (& how the system works). • MENTAL: Users build these in their heads. • Developed over time. • Not always correct (and usually not complete). • Thermostat example. • Lightswitch 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.

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

5. 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 came 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.

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

7. 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: physically do them. • Example.

8. 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.

9. The 7 stages (cont.) • Gulf of Execution. • How to get from 1 to 2, 2 to 3, or 3 to 4. • Example. • Gulf of Evaluation. • How to get to 5 at all, 5 to 6, 6 to 7. • Example.

10. The 7 stages as design aids • To find problems, apply these to any task in a UI: How easily can determine ... • 1. My Goal • 2. Exec: ...what relevant actions are possible? • 3. Exec: ...map those actions to physical moves? • 4. Exec: ...actually do the physical move? • 5. Eval: ...what state the system is in? • 6. Eval: ...what “that (feedback in UI)” means? • 7. Eval: if system is in desired state?

11. To find solutions 2: Exec: ...what relevant actions are possible? • Consider these remedies. • Visibility: • show what actions available (2). • Good mappings revealing: • relationships between actions and results (2), • controls (causes) and effects (3), • system state visible (5,6,7) • Feedback • every action provides immediate feedback of results (5,6,7) 3: Exec: ......map actions to physical moves? 5: Eval:...in what state? 6: Eval: …what feedback means? 7: Eval: …in desired state?