The world is complicated. there are over 30,000 everday things. How do people cope?

Basic point: much of everyday knowledge is not 'in our heads' but is in the material world

- things provide clues and cues

- environments and the organisation of things give bearings and act as mnemonics

- precision is not required in our daily lives (eg a dollar bill - you don't need to be aware of its specific details)

Norman outlines various aspects of people's dealings and interactions with things

SOME CONCEPTS FOR DEALING WITH THE INTERACTION BETWEEN PEOPLE AND THINGS

visibility and feedback

giving clue to people of what to do, and supplying feedback of things done

indicating the mapping between intended actions and actual operations

mappings

going fromwhat appears to be possible to what you want to do

eg - the relationships between controls and actions

affordances

an object may suggest a range of possibilities

the perceived and actual properties of things

• knobs are for turning

• slots for inserting

this incorporates a psychology of materials

• glass is to be broken

• wood is to be carved or written upon

constraints

limit the range of possibilities

• physical

• cultural

• logical

constraints may be mnemonics (eg rhymes)

All these allow the construction of CONCEPTUAL MODELS

examples

• doors

• telephones

• scissors

These are all basic principles of DESIGN

Norman's principle of good design is one of etiquette:

provide a good conceptual model and make things visible

the relationship between the artifact and user being one of cooperation and good manners