James J. Gibson analyzes the manner in which “the ‘values’ or ‘meanings’ of things in the environment could be directly perceived” (67). He draws from nature and the environment to postulate his theory of affordances, which is defined as “a specific combination of the properties of its substance and its surfaces taken with reference to an animal” (67). Under this definition, affordances are perceived through an invariant combination of properties, which are “meaningful” to a person—the properties in isolation are not.
His goes on to analyze the affordance of substances by claiming that the air affords breathing, while, after the application of his theory to surfaces and layouts, he claims that the ground affords standing on it. Further, he explains the affordance of detached objects by providing the example of manipulating a rope, among others, which allows knitting, binding, knotting. The most elaborate and rich affordances, according to Gibson, are provided by other people or animals. In this respect, he claims that behaviour affords behaviour, generating interactivity, such as touching, speaking, striking.
Gibson is influenced by the theory of valences developed by the Gestalt psychologists, for whom the relationship between the above listed things from the environment is subject to the needs of the observer. For Gibson, however, affordance does not have this “demand character” – the relationship between the objects, the substances, the surfaces, the animals and the people in the environment does not depend on the observer’s recognition of its affordance (77). For instance, a postbox affords letter-mailing to humans, whether the person perceives it or not – or as Gibson puts it: “The object offers what it does because it is what it is” (78).
Further, Gibson continues his emphasis on the objectivity of affordance by claiming that things which surround us will exist whether or not we perceive them as existing – an apple will always exist as a unique combination of shape, size, taste and colour. However, he is careful to add that the specific affordances are inseparable from our body – affordance is also “uniquely suited to a given animal” (79). This is why observers perceive edibility differently. For instance, the edibility of an apple is perceived in relation to observers’ individual “mouth, teeth, and digestive system” (79).
Finally, for Gibson, affordances in our environment can be misperceived by either failing to perceive something which exists or perceiving something which is not present. Visual perception fails because of an absence of stimulation (i.e. in the dark), eyes are closed, there’s an optical disease, “the observer has not yet learned to extract the specifying invariants,” or he fails to look at the fine details (Gibson 81). Affordances can be hidden as well, and the “demand character” may be lying (i.e. there may be a shark under the calm water) (82).