Design of Everyday Things Don Norman on Design & HCI
Today’s agenda • Project scores • Poster • 8400 topics • Design of everyday things • Midterm review • Next week: • 6:30-7:30: web design • 7:45-9:15: Midterm
Poster • March 12 (first class after spring break) • Present (at least) 3 design possibilities, get feedback • Organization: • General topic, perhaps scenario, users, requirements, etc. • At least 3 DIFFERENT designs – sketches, storyboards, perhaps descriptions or features • You can bring whatever else you have • Materials: whatever you like
Summary Darn these hooves! I hit the wrong switch again! Who designs these instrument Panels, raccoon?!
Don Norman • Professor at Northwestern and Principal of Nielsen Norman group • Previously Professor at UCSD, senior positions at Apple & HP • ACM/CHI Lifetime Achievement Award • Prolific author • http://www.jnd.org/
Discussion • What did you take away from DOET book so far?
Here are some • Affordances are important • Minimize the gulf of interpretation and gulf of execution • Use natural mappings • Make state visible • Use a conceptual model that makes sense • Provide feedback
Daily Challenges • How many of you can use all the functionality in your • VCR • Digital watch • Copy machine • Stereo system • Plumbing fixtures
Hall of Shame Example • Leitz slide projector • To move forward, short press • To move backward, long press • What happens when you get frustrated?
Changing Ringer Volume • Press “Program” • Press “6” • Set volume • Low - Press “1” • Medium - Press “2” • High - Press “3” • Press “Program”
Important Concepts • Affordances • Visibility • Conceptual models • Mapping • Feedback • Constraints
Affordances • Perceived and actual properties of an object that determine how it could be used • Chair is for sitting • Button is for pushing • Door handle is for …. • Scroll arrow is for … • Icon is for …
Door Opening Affordances • Which doors are easy to open? • Which doors are hard to open? • Why? 1 2 3 4 5 6 7
Affordances in interfaces • Interfaces are virtual and do not have ‘real’ affordances like physical objects • Interfaces have ‘perceived’ affordances • Learned conventions of arbitrary mappings between action and effect at the interface • Some mappings are better than others
Mantra • Complex things may need explanation, but simple things should not • If a simple thing requires instructions, it is likely a failed design • Norman’s 2 main principles • Provide a good conceptual model • Make things visible • Affordances is part of this
Conceptual Models • People build their own systems of how things work • Example - thermostat • Designer can help user foster an appropriate conceptual model • Appearance, instructions, behavior...
Conceptual Models • Mental models are not always right • Two Classes: • Functional model • Stimulus - response • “Press the accelerator once, then turn the key” • At surface or superficial level • Structural model • Deeper sense of why it happens, not just what happens • “Press the accelerator to engage the automatic choke on a carburetor”
Visibility • When functionality is hidden, problems in use occur • Occurs when number of functions is greater than number of controls • When capabilities are visible, it does not require memory of how to use • Recognition over Recall • in the world vs. in the head
Simple Example • Bathroom faucets • Two functions • Hot/cold • Flow
Bathroom Faucets 1 Can you figure out how to use it? Are two functions clear and independent?
Bathroom Faucets 2 Can you figure out how to use it? Are two functions clear and independent?
Bathroom Faucets 3 Can you figure out how to use it? Are two functions clear and independent?
5:45 My parent’s microwave
Mapping • Relationship between control and action/result in the world • Take advantage of physical analogies or cultural understandings • Good: • Car, various driving controls • Mercedes Benz seat adjustment example • Bad • Car stereo - Knob for front/back speakers
Mapping Example: Euros • Size::value
Mapping Example: Stove Which controls which?
Why Not Design Better • Stove • Speakers Physical, monetary, convenience, etc., constraints dictate otherwise
Feedback • Sending information back to the user about what has been done • Includes sound, highlighting, animation and combinations of these • e.g. when screen button clicked on provides sound or red highlight feedback: “ccclichhk”
Constraints • Limitations on what can be done • Physical - keys • Semantic - menu graying • Cultural - Colors • Logical - When all above don’t apply
Simple Example Electric plugs What if both sides were “big” and you had to remember which side the “small” one went into?
Head Not easy to retrieve Learning required, good conceptual model makes easier Can be very efficient Not easy first time Aesthetics do not need to make info visible World Easy to retrieve No learning, only interpretation Use slowed by need to find the info to interpret Easy for first time Can be cluttered or inelegant Knowledge in Head vs. Knowledge in the World
Execution-Evaluation cycle Norman (DOET, p. 46) Gulf of Execution User Goals Physical System Gulf of Evaluation
Goals, Execution, Evaluation Goals What we want to happen Execution What we do to the world Evaluation Comparing what happened with what we wanted to happen (Gulf of Execution) (Gulf of Evaluation) Physical System
Execution Goals What we want to happen An intention to act so as to achieve the goal The actual sequence of actions that we plan to do The physical execution of that action sequence Physical System
Evaluation Goals What we want to happen Evaluation of the interpretations with what we expected to happen Interpreting the perception according to our expectations Perceiving the state of the world Physical System
Seven Stages - All Together Goals What we want to happen An intention to act so as to achieve the goal Evaluation of the interpretations with what we expected to happen The actual sequence of actions that we plan to do Interpreting the perception according to our expectations The physical execution of that action sequence Perceiving the state of the world Physical System
Implications – Which Gulf does these Address? • Make current state and action alternatives visible • Need good conceptual model with consistent system image • Interface should include mappings that reveal relationships between stages • User should receive continuous feedback • Provide affordances
Gulf of Execution Conceptual model Affordances Natural mappings Gulf of Evaluation Make state visible Feedback Goal: Minimize Gulfs
Errors - Three Considerations • Avoiding and preventing • Identifying and understanding • Handling and recovering
Why errors are important Errors are unavoidable To err is human Making mistakes is part of learning Designer’s responsibility Understand why errors occur Minimize likelihood Allow for recognition of error and graceful recovery (forward or backward)