Affordance

Affordance

From Wikipedia, the free encyclopedia

An Affordance is an action that an individual can potentially perform in their environment. However, the more exact meaning depends on whether the word is used to refer to any such action possibility or only to those which the actor is aware of, both of which are common uses. The term is used in the fields of perceptual psychology, cognitive psychology, environmental psychology, industrial design, human–computer interaction (HCI), interaction design and artificial intelligence.

History & Definitions

Psychologist James J. Gibson originally introduced the term in his 1977 article The Theory of Affordances[1] and explored it more fully in his book The Ecological Approach to Visual Perception[2] in 1979. He defined affordances as all "action possibilities" latent in the environment, objectively measurable and independent of the individual's ability to recognize them, but always in relation to the actor and therefore dependent on their capabilities. For instance, a set of steps which rises four feet high does not afford the act of climbing if the actor is a crawling infant.

In 1988, Donald Norman appropriated the term affordances in the context of Human–Machine Interaction to refer to just those action possibilities which are readily perceivable by an actor. Through his book The Design of Everyday Things,[3] this interpretation was popularized within the fields of HCI and interaction design. It makes the concept dependent not only on the physical capabilities of the actor, but also their goals, plans, values, beliefs and past experience. If an actor steps into a room with an armchair and a softball, Gibson's original definition of affordances allows that the actor may toss the recliner and sit on the softball, because that is objectively possible. Norman's definition of (perceived) affordances captures the likelihood that the actor will sit on the recliner and toss the softball, because of their past experience with these objects. Effectively, Norman's affordances "suggest" how an object may be interacted with.

Norman later explained that this adaptation of the term had been unintended.[4][5] However, the definition from his book has become established enough that both uses have to be accepted as convention.