1/20/2008
1
Design of Everyday Things
- Donald Norman
CS A470
Overview
• Why are some everyday things difficult to
understand and use?
• What are Don Norman’s principles and how
do they apply to the design of everyday
things?
• How can we apply Norman’s principles to
the design of computer interfaces?
1/20/2008
2
Psychopathology of Everyday
Things
• We are surrounded by many everyday things that
have poor
usability
– Programming a VCR
– Telephone features we can’t remember how to use
• How to change the remote access code?
– Photocopiers and fax machines
• Face down or face up?
• Many of these things can be difficult to interpret
and frustrating to use if they provide no clues or
false clues as to how they operate
Why is usability important?
• poor usability results in
– anger and frustration
– decreased productivity in the workplace
– higher error rates
– physical and emotional injury
– equipment damage
– loss of customer loyalty
– costs money
1/20/2008
3
What is usability?
Usability is a measure of the
effectiveness
,
efficiency
and
satisfaction
with which specified users
can achieve specified goals in a
particular environment.
• ISO 9241
Examples of Poor Design
• Trapped between
doors!
• Handles
afford
pulling
• Using a flat plate
would
constrain
the
user to push
1/20/2008
4
Examples of Poor Design
• Wireless Powerpoint slide controller
– Short press to go forward
– Long press to go backward
• Refrigerator temperature control
– Two compartments and two controls
– One cooling unit
Temperature Control
1/20/2008
5
Norman’s Principles of Design
• Make things visible
• Provide a good conceptual model
– Affordance
– Mapping
– Constraints
– Feedback
Visibility
• The correct parts must be visible and they must
convey the correct message
• Natural signals are naturally interpreted
• Visibility problems occur when clues are lacking
or exist in excess
• Just by looking the user should know
– State of the system
– Possible actions
• Don’t violate these principles to make something
“look good”!
1/20/2008
6
How fast are we going?
The well-trodden path
1/20/2008
7
Please Push Slowly!
• Wonder why doors are
made out of glass?
Evidently someone was
smacked...
The case of the mistaken urinal