More on Design of Everyday Things

Turn it up, or shut it down?

Welcome to the hall of shame! ●signifiers are present ●this is an execution problem ○specifically the “perform” step ●should there really be a one-touch shortcut to close all tabs?

Bad Microwave My microwave has a problem. It has a huge problem, actually. Can you identify it?

Bad Microwave ●The problem with this microwave is that there is no way to specify “Add thirty seconds” after I input a number. ●Therefore, my food can only be cooked in thirty second increments, if I’m lazy. ●The microwaves programming only allows me as a user to input a specific time, or any product of thirty seconds.

So how does a designer help users acquire the right model? Visibility Affordances Constraints Mappings Feedback

Constraints Limit the range of possible actions Physical Constraints –Only some possibilities are physically possible (only one way to put a VCR tape in a player) Semantic Constraints –Only some possibilities make sense Cultural Constraints –Only some possibilities are acceptable Logical Constraints –General principles: e.g., every part should be used

Feedback Remember that people will build models –And feedback leads to causal models: “if Y happened after X, then X caused Y” So provide the proper feedback immediately: respond to user actions – don’t hide the results! –Did I press the button? (visual and/or audio feedback) All actions should have effects –Promote exploration

Knowledge In The World Recognition, not Recall Partial, “good enough” descriptions stored

Put knowledge in the world So users don’t have to keep it all in their heads –Menus, toolbars –Agendas –Graphical workspaces Provide memory aids –so users don’t have to remember information between screens

To err is human… Slips – errors in automatic actions: easy to detect –Capture errors –Description errors –Data-driven errors –Associative action errors –Loss of activation errors –Mode errors Mistakes – errors in intention or logic: hard to detect

Preventing errors Avoiding slips –Different things should look different –Consistent confirmation is not useful –Immediate confirmation may not be useful Simplify tasks –Make task structure narrow or shallow

Ooops, I opened my trunk Controls to open trunk and access gas tank are right next to each other

More ways to prevent errors Support recovery –Undo and backups –Support exploration toward a goal Prevent errors with forcing functions –failure in one step means later steps can’t be done –Make illegal actions unavailable –Disable buttons or menus –Turn illegal actions into legal ones

Last resort - standardization Fewer things to memorize Quicker to learn Clocks should run clockwise But note that standards are culture- dependent!

“Standards” and cultures What does the color red mean? –US – danger, warning, … –India – purity What color should a wedding dress be? –US – white –India – red & yellow How do you turn on a faucet? –US – counter-clockwise –UK – clockwise Problems with icons – mailboxes, trashcans, …

Applying the principles

A usable design - scissors Affordances –Holes for something to be inserted Constraints –Big hole for several fingers, small hole for thumb Mappings –Between holes and fingers suggested and constrained by appearance A cultural standard Conceptual model –Implications of actions clear – feedback is immediate

A problematic design – digital watch Affordances –4 buttons to push, but not clear what they do Constraints, mappings –Unknown – no natural relations or constraints Transfer –Little/none from analog watches Standardization –Still quite variable

How do I pump the gas?

“Push To Start”

Design Principle Problems Visibility Affordances

When does the bottom light go on?

Design Principle Problems Conceptual Model Feedback

Setting Options in MS Word

Design Principle Problems Conceptual model – “What happened?!?”

Which string turns on the fan, which turns on the light?

Design Principle Problems Mappings

What’s that thing in the corner?

It’s a mop sink!

Design Principle Problems Affordances Conceptual Model Standardization

How do you raise/lower this screen?

Design Principle Problems Conceptual Model Mappings

Wrapping up DOET Reflecting on DOET: –Was written 25+ years ago –Talks about things like doors, slide projectors, refrigerators, not GUIs –So how well does it apply to designing GUIs in 2015?

Next Steps For next time –Begin discussion on how to interact with users Project – Friday, September 11 –Project Proposal Due –But we won’t do studio on this until next week.