Affordances (Gibson/Norman)

Affordances are action possibilities relative to an actor's capabilities. Norman distinguishes actual and perceived possibilities and emphasizes signifiers that communicate how to act. A cue and an available action are not the same thing.

An affordance is a possibility for action arising from the relation between an environment or object and an actor's capabilities. A surface may support sitting for one person but not another. This differs from a signifier, which communicates where or how to act. A label can indicate an action without making that action physically or technically possible.

Inspect capability, perception, and feedback separately. If a person cannot operate a control, the problem might be reach, force, a misleading cue, or an unclear result. Adding instructions only addresses some of these. Improve the relevant relationship and test it with people who have differing capabilities; an attractive or familiar appearance does not guarantee access or correct interpretation.

When to use it

When users consistently misuse products or processes; when the 'obvious' way to use something is wrong; when designing interfaces, spaces, or processes; when training and instructions seem necessary to use something that should be intuitive.

How it can help

Inspect capability, cues, constraints, and feedback separately when use fails. Improve the relevant feature and test with people whose abilities and experience vary.