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An affordance is a relation between an object or an environment and an organism that, through a collection of stimuli, affords the opportunity for that organism to perform an action.〔 See also a list of various definitions titled ("What are affordances", p. 91 )〕〔 〕 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. Different definitions of the term have developed. The original definition described all actions that are physically possible. This was later adapted to describe action possibilities of which an actor is aware. Some define affordance as a potential resource for ''some'' (not a particular) organism or species of organism, and so while inviting the possible engagement of some species, not identified with any particular one.〔 〕〔For an extended discussion of views on affordances, see 〕 The term has further evolved for use in the context of human–computer interaction (HCI) to indicate the easy discoverability of possible actions. The word is used in a variety of fields: perceptual psychology, cognitive psychology, environmental psychology, industrial design, human–computer interaction, interaction design, communication studies, instructional design, science, technology and society (STS), and artificial intelligence. == As action possibilities == Psychologist James J. Gibson originally introduced the term in his 1977 article "The Theory of Affordances"〔James J. Gibson (1977), The Theory of Affordances. In ''Perceiving, Acting, and Knowing'', edited by Robert Shaw and John Bransford, ISBN 0-470-99014-7.〕 and explored it more fully in his book ''The Ecological Approach to Visual Perception''〔James J. Gibson (1979), ''The Ecological Approach to Visual Perception'', ISBN 0-89859-959-8.〕 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 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. Gibson's is the prevalent definition in cognitive psychology. Affordances were further studied by Eleanor J. Gibson, wife of James Gibson, who created her theory of perceptual learning around this concept. Eleanor Gibson's book, ''An Ecological Approach to Perceptual Learning and Development'' explores affordances further. Jakob von Uexküll had already discussed the concept in the early twentieth century,〔Uexküll, Jakob von (1980 (etc. )), ''ドイツ語:Kompositionslehre der Natur'', edited by Thure von Uexküll, Frankfurt am Main.〕 calling it the "functional tinting" (''ドイツ語:funktionale Tönung'') of organisms with respect to stimuli. Anderson, Yamagishi and Karavia (2002) sought to determine whether visual attention or affordance forms the basis of the motor signals generated by many everyday graspable objects. By examining how the properties of an object affect an observer’s reaction time for judging its orientation, they provided evidence to indicate that directed visual attention (not affordance) is responsible for the automatic generation of many motor signals associated with the spatial characteristics of perceived objects. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「affordance」の詳細全文を読む スポンサード リンク
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