Affordance

An affordance is a property of an object, or a feature of the immediate environment, that indicates how to interface with that object or feature. The empty space within an open doorway, for instance, affords movement across that threshold. A couch affords the possibility of sitting down on it. Workers in the field of perceptual psychology use this concept, as well as workers in the fields of cognitive psychology, environmental psychology, industrial design, and human-computer interaction. Psychologist James J. Gibson introduced the term in 1966, then explored it more fully in his book The Ecological Approach to Visual Perception in 1979. Gibson originally meant affordance to refer to all "action possibilites" latent in the environment, objectively measureable, and independent of the individual's ability to recognize those possibilities. Further, those action possibilities are dependent on the capabilities of the actor. For instance, a set of steps with risers four feet high does not afford the act of climbing, if the actor is a crawling infant. So affordances must be measured along with the relevant actors. In 1988, Donald Norman refined the term to refer to perceived affordance, as opposed to an objective affordance that is directly perceived. This distinction that makes the concept dependent not only on the physical capabilities of the actor, but their goals, plans, values, beliefs and interests, as identified in ecological cognition. If an actor steps into a room with a recliner (an armchair) and a softball, Gibson's definition of affordance allows that the actor may toss the recliner and sit on the softball, because that's objectively possible. Norman's definition of perceived affordance captures the likelihood that the actor will sit on the recliner and toss the softball, because of their experience with them in the past. Norman's definition makes the concept of affordance subjective rather than objective, and therefore out of the realm of hard science (but not social science). On the other hand, the concept of perceived affordance is much more pertinent to practical design problems. Perceptual psychologists can ask, "What is it about this object that makes people want to use it this way?" The object must talk to us with some sort of language. If we can understand this language, then industrial designers can make tools that explain their own functions, and even tools that recommend themselves for some uses and discourage other uses. Ecological cognition using neuroimaging studies suggests that when an actor either objectively or subjectively perceives an affordance they will develop a plan to act on that affordance and will act on that plan unless they experience Cognitive dissonance. Dissonance can lead to the actor using an object in a way other than the way it suggests through its affordances. See also Usability Ecological cognition Related literature Gibson, The Ecological Approach to Visual Perception, ISBN 0898599598 Donald Norman, The Design of Everyday Things, ISBN 0465067107 Donald A. Norman (1999). Affordances, Conventions and Design. Interactions 6(3):38-43, May 1999, ACM Press. External links Affordance, Conventions and Design by Donald Norman The Interaction-Design.org encyclopedia entry on Affordances EU project to build an affordance based robot control architecture Search Term: "Affordance" Categories: Perception | Cognition | Human-computer interaction