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Psychology 384 Human Factors Laboratory. The Psychopathology of Everyday Things. Today’s sources: Don Norman. Things That Make Us Smart Turn Signals are the Facial Expressions of Automobiles The Design of Everyday Things (formerly: The Psychology of Everyday Things).
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Psychology 384 Human Factors Laboratory The Psychopathology of Everyday Things
Today’s sources: Don Norman • Things That Make Us Smart • Turn Signals are the Facial Expressions of Automobiles • The Design of Everyday Things (formerly: The Psychology of Everyday Things)
The Psychopathology of Everyday Things Why are some common things so hard to use? • Doors • Stoves • Faucets • Light switches • Refrigerators • (you name it!)
??? PUSH
Affordances: Norman: the perceived and actual properties of things in the environment that determine just how those things might be used by a human being Affordances provide clues for forming mental models.
Key to bad design: • Look for a sign!
ATTENTION The light level in this room is controlled by pushing the numbered buttons. Number 1 = 100% (Brightest) Number 2 = 75% Number 3 = 50% Number 4 = 25% (Dimmest) Number 5 = 0% (Off) DO NOT USE “ON”/”OFF” BUTTON DO NOT USE ANY OTHER BUTTON WITHOUT INSTRUCTIONS
The Design Follies prize: Welcome to the Del Mar Post Office vending machine. I refund a maximum of $3.25 change with your purchase. Think before depositing a bill larger than $5. (This kind of situation, from which there is no recovery, has been called a dead end or “deadly embrace”)
Human factors in the cockpit • $$$ • Complex, high-tech setting • The consequences of errors can be disastrous
Human factors in the cockpit Some sources of errors and disasters: • Social interaction among the flight crew • Automatic controls • Badly designed controls • Information overload
Why things don’t work Designer User System
Why things don’t work • Designers fail to take users’ perspective • Form is rewarded over function • User studies take time and resources • Good design is iterative: Observe Design
Why things work as well as they do: • The principle of MAPPING: Natural vs. arbitrary mappings
Example: Shape coding • Seat adjustment control for a Mercedes Benz (A natural mapping)
Why things work as well as they do: • The principle of MAPPING: Natural vs. arbitrary mappings • The principle of FEEDBACK
Why things work as well as they do: • The principle of MAPPING: Natural vs. arbitrary mappings • The principle of FEEDBACK • FORCING FUNCTIONS (Designing for error)
A refrigerator’s helpful diagram: Normal settings C and 5 Colder fresh food C and 6-7 1. Set both controls Coldest fresh food B and 8-9 2. Allow 24 hours Colder freezer D and 7-8 to stabilize Warmer fresh food C and 4-1 Off (fresh fd & frz) 0 A B C D E 7 6 5 4 3 Freezer Fresh food
A mental model: Freezer Freezer control Cooling unit Cold air Fresh food control Fresh food Cooling unit Cold air
The real model: Thermostat Control A Freezer Valve Cold air Cooling unit Fresh food Control B
User-centered system design:Some principles (from Norman) • Represent the required knowledge in the world (not in the head) • Provide appropriate feedback • Use the power of natural and artificial constraints: physical, logical, semantic, cultural • Test with real users (not w/ designers - they know too much!)
Intuitive design has all the virtues of theft over honest toil. - Alan Newell, quoting Bertrand Russell
Roles of cognitive psychologists in industry: 1. Collecting data (observations & experiments) 2. Designing things 3. Giving advice
What HCI psychologists do: • Design help systems, documentation, dialogs, and screen representations • Act as advocates for users and ideas • Predict the success or failure of designs • Observe users and suggest changes • Compare alternatives • Advise marketing and engineering folk • Help make design tradeoffs
Tradeoffs are made between: • powerful, complicated systems vs. less powerful but easy to learn systems • time vs. money • speed vs. functionality or resolution • changing one part of the interface may make an enormous difference in usability (for better or worse)
What HCI psychologists do:(cont.) • Test new products w/ focus groups • Study effects of technology on individuals and organizations • Develop and prototype new ideas • Research new uses of technology - visualize the future