Affordances

An affordance is a relationship between an object and an agent: the actions the object makes possible given that agent's capabilities. A chair affords sitting; a handle affords pulling. Affordances exist whether or not anyone perceives them.

Why it Matters

Designing the right affordances makes correct actions physically possible and wrong ones impossible. Trouble arises when an affordance exists but is not perceivable, or when an object affords an action it should not.

Signals

• Users attempt actions the object does not support, or miss ones it does.
• "What can I do here?" has no clear answer from the object itself.

Benefits

The correct actions become possible and natural without instruction or labels.

Risks

Conflating an affordance (what is possible) with a signifier (what is communicated); an affordance nobody perceives is useless. Adding false affordances that suggest impossible actions.

Tensions

Real affordances versus perceived ones: on screens almost everything is a perceived affordance conveyed by signifiers, so for digital design the signifier usually matters more than the underlying affordance.

Examples

A flat plate affords pushing a door; a glass affords grasping; a slot affords inserting a card.