Echoes of the Real World · principle
Affordances & Signifiers
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An affordance is what an object lets you do (a button affords pressing); a signifier is the signal that tells you the affordance is there (the button looks pressable). Users don't read manuals — they act on what a control appears to offer. When the signifier is missing or misleading, you get confusion; when it's clear, the interface explains itself.
Where it comes from
'Affordance' was borrowed from the ecological psychologist James J. Gibson and brought into design by Don Norman in his 1988 book The Design of Everyday Things; Norman added the term 'signifier' in the 2013 edition to name the perceivable signal of an affordance. His canonical real-world example is the 'Norman door' — a door whose handle affords pulling but that must be pushed, because the signifier lies. Norman also coined the term 'User Experience' at Apple, and these six principles became the vocabulary of the profession.
Origin: Don Norman's The Design of Everyday Things (1988/2013) and the 'Norman door'
In the wild
- Buttons vs flat text
A raised, coloured button signifies 'click me'; the same action as plain text loses the signifier and gets missed.
- Underlined links
The underline is a signifier that this text affords navigation — remove every cue and users can't tell what's clickable.
- Disabled states
Greying out a control is a signifier of a constraint: it communicates 'not available right now' without an error.
Further reading
Don't just read it — feel it.
Play the 3-minute game and let your own reactions prove the law.
Play the lesson