more on design of everyday things. turn it up, or shut it down?
TRANSCRIPT
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.