Reflections on 20 Years of Affordance-Based Design

Abstract

Twenty years after first applying the concept of affordance to engineering design, here we reflect on the history of how the concept of affordance from perceptual psychology came to be applied to design, not only of man-made things but of natural phenomena as well, from the universe as a whole to why a dog walks differently from a person. An important controversy over the years has also been the need for a precise definition of affordance. After considering why a mathematical definition is unsuitable, a proper definition is proposed: an affordance is a relationship between two (or more) interacting systems that describes a potential behavior that neither system can exhibit alone. Several examples are given, with three different naming conventions discussed and several tantalizing open issues that deserve attention in the future.