BEHAVIORIST

Behaviorist

Behaviorist

Modern behaviorists are concerned primarily with the causes of operant behaviors: the voluntary actions that comprise the vast majority of human behavior. Behaviorists believe that operant behaviors are “selected” by their consequences at three distinct levels, beginning with Darwinian natural selection. Thus, behavior is a function of an organism's genetic endowment, as evolution selects certain behavioral characteristics over the lifetime of a species; of the organism's environment, as contingencies of reinforcement and punishment select and modify the behavior of the organism during its lifetime; and of the social/cultural environment, as social or cultural contingencies select broader practices affecting the social group of which the individual organism is a member. Although all three levels are important for understanding the full context in which behavior occurs, the middle level—the contingencies of reinforcement that modify behavior during an organism's lifetime—has been the primary focus of behavior analysis.

Contingencies of reinforcement comprise three variables that are defined in terms of each other and that form a single, interrelated system linking behavior and environment: an operant, defined as a behavior that operates on the environment to produce some consequence or effect that, in turn, modifies the subsequent occurrence of the operant; a stimulus consequence, defined as an environmental consequence or outcome of a behavior that modifies its subsequent occurrence; and a discriminative stimulus, defined as an environmental stimulus that marks an occasion on which, in the past, the occurrence of an operant has produced a particular reinforcer. For example, students learn that when in a classroom (a discriminative stimulus), raising one's hand (an operant) is the way to be called upon by the instructor. How the instructor responds to the student's comment or question (the stimulus consequence) will tend to modify its occurrence, either increasing or decreasing the probability of the student's future hand-raising behavior.

All operants and stimuli are members of classes of similar phenomena, defined by the environmental relations in which they participate. Classes of operant behavior are created by differential reinforcement with respect to classes of discriminative stimuli. For example, closing a door with one's foot, hand, or elbow are all ways of responding to a cold draft created by an open door, and all will be reinforced by a reduction in cold. Stimulus consequences are classified by their effects on behaviors: Those that increase or strengthen the behaviors on which they are contingent are called “reinforcers”; those that decrease or weaken behaviors are called “punishers.” Both reinforcers and punishers can be either positive or negative, depending on whether their effect is produced by presenting (adding) or removing (subtracting) the stimulus, thus creating a fourfold table that classifies stimulus consequences by their effects on behavior (an increase or decrease in strength) and by whether these effects are produced by presenting or removing the stimuli. A positive reinforcer is a stimulus consequence whose addition strengthens behavior (e.g., approval for work performed); a positive punisher is a consequence whose addition weakens behavior (e.g., a traffic ticket for speeding); a negative reinforcer is a consequence whose removal strengthens ...