Psychologist James J. Gibson originally introduced the term “affordance” in his 1977 article ‘The Theory of Affordances’, which he subsequently elaborated his book The Ecological Approach to Visual Perception in 1979. Gibson 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 agents 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.
An affordance is a relation between an object or an environment and an organism, that affords the opportunity for that organism to perform an action. For example, a knob affords twisting, and perhaps pushing, while a cord affords pulling. As a relation, an affordance exhibits the possibility of some action, and is not a property of either an organism or its environment alone.
“The affordances of the environment are what it offers the animal, what it provides or furnishes, either for good or ill. The verb to afford is found in the dictionary, but the noun affordance is not. I have made it up. I mean by it something that refers to both the environment and the animal in a way that no existing term does. It implies the complementarity of the animal and the environment. The antecedents of the term and the history of the concept will be treated later; for the present, let us consider examples of an affordance…” ~ James J.Gibson (1979)
READ MORE HERE: http://cs.brown.edu/courses/cs137/readings/Gibson-AFF.pdf