Ferster & Skinner. (1957). Schedules of reinforcement.


When an organism acts upon the environment in which it lives, it changes that environment in ways which often affect the organism itself. Some of these changes are what the layman calls rewards, or what are now generally referred to technically as reinforcers: when they follow behavior in this way, they increase the likelihood that the organism will behave in the same way again. Most events which function as reinforcers are related to biological processes important to the survival of the organism. Thus, food is reinforcing to a hungry organism. The capacity to be reinforced by food substances has presumably been acquired as part of the evolutionary development of the species. Because of the strengthening of behavior which follows, the behavior of the organism is “shaped up” so that it is maximally effective in any particular environment. The shaping process includes the differentiation of new forms of response, including the subtle refinements of form called skill. It also includes the development of appropriate stimulus control, so that a given response is generally emitted only upon an appropriate occasion. The traditional study of reinforcement in the field of learning has been almost exclusively concerned with the acquisition and retention of behavior in this sense. It is argued that another important function of a reinforcement is to maintain an active repertoire of behavior. We deal with conditions at the moment of reinforcement in two ways: (1) inferentially, by comparing the effects of different schedules and particularly of schedules designed primarily to make such inferences most plausible; and (2) by direct manipulation or determination. The primary purpose of the present book is to present a series of experiments designed to evaluate the extent to which the organism’s own behavior enters into the determination of its subsequent behavior. From a formulation of such results we should be able to predict the effect of any schedule.