Human Capabilities: Mental Models

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.

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.

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.

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.

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) 3. execution: sequence of actions. 4. execution: physically do them.

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. 7. evaluation: comparison of interpretation with goal.

The 7 stages (cont.) Gulf of Execution. Gulf of Evaluation. 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.

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? Could do example using Block-a-pix, the way I saw Ellie interact with it, but no need really because we did an example with the slide projector. * 1. color blocks st everything filled. 2. But WHAT FEATURES/ACTIONS are relevant here? 3. “You have to stretch the block”. to do that, grab it and pull 4. can’t grab it and pull. too high, doesn’t keep thumb down, etc., etc.

To find solutions Consider these remedies. Visibility: 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?