Affordances: A New Ecology for Psychology
Ecological psychology holds that behavior and awareness are an animal's ways of discovering and using key resources--the values and meanings--of the animal's surroundings. Human beings are no different from other animals in this regard, although we have evolved some novel cooperative methods for these processes of discovery and use. The key to understanding resource use, whether in evolution generally or more specifically in regard to psychological evolution, is to find the selective processes that constrain and change the varieties of resource use found in a population (see Darden & Cain, 1989, for more on "selectionist" theories in general). This chapter argues that the source of the psychological components of natural selection are the affordances of the environment. It is argued that these affordances select and shape animal behavior and awareness, not only on the time scale of natural selection but also within more narrow time scales, such as that of ontogeny, learning, and individual behavioral acts. The concept of affordances as the basis of animacy and sentience is ecological psychology's contribution to our general understanding of the evolution of animals within the environment.
Animate behavior and sentience are natural events: they are evolved aspects of all animals and as such exist within the environment in specific ways. Our terrestrial environment encompasses many things, from small particles of sand and even smaller unicellular creatures on up to trees, fields, lakes, forests, and even larger entities that shape whole continents, such as rivers and mountain ranges. The events of our environment also vary from the microscopic in time to cycles of extremely long duration, from the momentary dappling of shade under a tree to the diurnal cycle of night into day, to seasonal cycles, on up to geological events such as the elevation or subsidence of mountain ranges. How does behavior fit into these scales of our environment, and what are the limits of variability of behavior within our terrestrial ecology?
Darwin studied earthworm behavior because he was interested in an important ecological effect of their behavior: the formation of topsoil. To study the rate of deposition of soil by the action of worms, Darwin had to conduct experiments over a period of decades ( Darwin, 1837/ 1977, 1869/ 1977). Although the activities of individual worms obviously take place over much shorter durations and smaller areas, the effects