Affordance Theory

Affordance Theory

The great perception theorist J. J. Gibson (Gibson, 1979) brought about radical changes in the ways we think about perception with his theories of ecological optics, affordances and direct perception. 

Gibson assumed that we perceive in order to operate on the environment. Perception is designed for action. Gibson called the perceivable possibilities for action affordances. He claimed that we perceive affordance properties of the environment in a direct and immediate way. This theory is clearly attractive from the perspective of visualization. The goal of most visualization is decision making. In short, Gibson claims that we perceive possibilities for action. i.e. surfaces for walking, handles for pulling, space for navigation, tools for manipulating, etc. In general, our whole evolution has been geared toward perceiving useful possibilities for action.

Affordance example: (Norman, 1988)

You are approaching a door through which you eventually want to pass. The door, and the manner in which it is secured to the wall, permits opening by pushing it from its 'closed' position. We say that the door affords (or allows, or is for) opening by pushing. On approaching that door you observe a flat plate fixed to it at waist height on the 'non-hinge' side, and possibly some sticky finger marks on its otherwise polished surface. You deduce that the door is meant to be pushed open: you therefore push on the plate, whereupon the door opens and you pass through. Here, there is a perceived affordance, triggered by the sight of the plate and the finger marks, that is identical with the actual affordance. Note that the affordance we discuss is neither the door nor the plate: it is a property of the door (the door affords opening by pushing ).

Gibson, J.J. (1979). The Ecological Approach to Visual Perception , Houghton Mifflin, Boston. (Currently published by Lawrence Eribaum, Hillsdale, NJ.)

Norman, D. (1988). The Psychology of Everyday Things , New York, Basic Books, pp. 87-92.