What is an Affordance?
I am not a designer, and I’ve always wondered what an affordance is in the context of design. In The Design of Everyday Things, Norman defined the term as follows:
An affordance is a relationship between the properties of an object and the capabilities of the agent that determine just how the object could possibly be used.
What does it mean? Let me give you an example. The door on the left affords “pull”, because the handle has the meaning of pull for a door open. On the other hand, the right one has the “push” accordance with the flat plate.
Please note that Norman’s concept of an affordance is different from the original one coined by Gibson, a perceptual psychologist. He described it in The Ecological Approach to Visual Perception:
The affordances of the environment are what it offers the animal, what it provides or furnishes, either for good or ill.
Norman focused on the information that specifies how the object can be used, but Gibson’s affordance is independent of the actor’s ability to perceive it. Norman explained that he would replace it by “perceived affordance” later. However, his definition has been widely accepted.
That’s why we confuse an affordance. Although Norman’s use of term is distinct from Gibson’s, an affordance is the important concept for a user experience.