Upload
norman-white
View
26
Download
0
Embed Size (px)
DESCRIPTION
SIMS 213: User Interface Design & Development. Marti Hearst Tues, Feb 11, 2003. Norman’s Design Principles. How new users understand what to do: Four principles for screen interfaces Follow conventional usage, both in the choice of images and the allowable interactions. - PowerPoint PPT Presentation
Citation preview
SIMS 213: User Interface Design & Development
Marti HearstTues, Feb 11, 2003
Norman’s Design Principles
How new users understand what to do: Four principles for screen interfaces– Follow conventional usage, both in the choice
of images and the allowable interactions.– Use words to describe the desired action (e.g.,
"click here" or use labels in front of perceived objects).
– Use metaphor.– Follow a coherent conceptual model so that
once part of the interface is learned, the same principles apply to other parts.
From http://www.jnd.org/dn.mss/affordances-and-design.html
Cognitive Considerations
From Don Norman’s book, The Psychology (Design) of Everyday Things– Affordances, Constraints, and Mappings– Mental Models– Action Cycle and Gulf of Execution
Affordances
The perceived properties of an object that suggest how it can be used.Popularized by D. Norman in POET– The perceptual psychologist J. Gibson had a similar, but
different, notion.– Norman contrasts real vs. perceived affordances– Subsequent clarifications on affordances by Norman:
• http://www.jnd.org/dn.mss/affordances-and-design.html
Affordances
The perceived properties of an object that determine how it can be used.– Knobs are for turning.– Buttons are for pushing.
Some affordances are obvious, some learned– Glass can be seen through.– Glass breaks easily.
Sometimes visual plus physical feedback– Floppy disk example
• Rectangular – can’t insert sideways• Tabs on the disk prevent the drive from letting it be fully inserted
backwards
Norman’s Affordances
Affordances:– Have perceived properties that may or may not exist– Have suggestions or clues about to how to use these
properties– Can be dependent on the
• Experience• Knowledge• Culture of the actor
– Can make an action easy or difficult
From McGrenere & Ho, Proc of Graphics Interfaces, 2000
Affordances of a Teapot?
Slide adapted from Saul Greenberg
Real vs. Perceived Affordances
From http://www.jnd.org/dn.mss/affordances-and-design.html :
In product design, where one deals with real, physical objects, there can be both real and perceived affordances, and the two need not be the same.
In graphical, screen-based interfaces, all that the designer has available is control over perceived affordances.
Based on slide by Saul Greenberg
Affordances in Screen-Based Interfaces
Designer only has control over perceived affordances– Display screen, pointing device, selection buttons,
keyboard– These afford touching, pointing, looking, clicking on
every pixel of the display.
Based on slide by Saul Greenberg
Affordances in Screen-Based Interfaces
Most of this affordance is not used– Example: if the display is not touch-sensitive, even
though the screen affords touching, touching has no effect.
– Example: • does a graphical object on the screen afford clicking?• yes, but the real question is does the user perceive this
affordance; does the user recognize that clicking on the icon is a meaningful, useful action?
Visual affordances of a scrollbar
Affordances
More examples?See Strauss Mouse Video