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Disruption Of Behavior By A Changein Stimuli

The Environmental Control

The more closely an individual's behavior is controlled by the environment, the more susceptible it is to disruption by a change in environmental conditions. The continuous development of discriminative control may represent, depending on other contributing factors, either weakening or strengthening of the general behavioral repertoire. The closer the child's behavior conforms to the particular situations in which reinforcement is possible, the higher will be the frequency of reinforcement, because all of the child's behavior is occurring where it is effective. On the other hand, the prolonged and pervasive extinction of the child's behavior during the course of the development of stimulus control by the environment produces a possibility that the repertoire will be markedly weakened in the event of a sudden and radical change. The spinster woman living in isolation with a sister or an elderly parent represents an extreme situation of this kind. In many such cases the outside community loses all control of the individual's behavior, because it no longer presents any occasions on which any significant behavior is reinforced. At the same time, almost all of the person's behavior is under the control of the companion. The death of the companion may produce a severe and pathologic depression because the companion provided literally all of the reinforcers supporting the individual's behavior. While clinical depression is an extremely complex phenomenon which in any individual case may be determined by several factors concurrently, in its broadest sense it refers largely to changes in the frequency of a large number of items in the individual's repertoire. Sudden changes in the general environment controlling the individual's behavior may be a large. factor contributing to such depressions. The close and intimate relationship between two individuals to the exclusion of the outside community is the equivalent of procedures that place the individual's behavior very narrowly under the control of specific stimuli. In this case the loss, in the death of the companion, of the discriminative stimuli supporting the individual's behavior is an effective way of weakening the general repertoire, because these persons are lacking behavioral repertoires which can be sustained by effects in the outside environment.

During adolescence, there are gross changes in the environment and the corresponding reinforcement conditions. Adolescent schizophrenia may occur partly because during this period the physically developing child is suddenly exposed to a whole new environment in which many of the repertoires previously reinforced are no longer appropriate. Few demands are made by the community on many adolescents; schedules of reinforcement are optimal and the chains of responses leading to major reinforcers are short. The adolescent does not hold a regular job, his main occupation is school, and the remaining repertoires consist of social behaviors which are relatively easy to maintain. The graduation from school and the sudden change in the social organization in the community presents a whole new environment with new reinforcement contingencies. The swiftness with which this environment changes and the extent to which performances are present in the adolescent repertoire capable of having an effect in the new environment are the factors which determine how disrupting will be the transition. It is possible to hypothesize a paradoxical situation in which an adolescent, whose repertoire is most effective in dealing with the adolescent environment, may be the individual most susceptible to gross disturbances in the transition to adulthood.

Conditioned Reinforcement

Most reinforcers which control behavior are conditioned. In producing new behavior in an animal experiment, for example, the actual reinforcers which are used are sounds and lights rather than food. These stimuli reinforce behavior because they, in turn, are the occasions on which further behaviors are reinforced. Even behavior as simple as a pigeon pecking a key is a complex behavioral chain, held together by several conditioned reinforcements: turning toward the key is reinforced by the sight of the key, pecking at the key is reinforced by the sight and sound of the food magazine light, in the presence of the food magazine light and sound, lowering the head to the hopper is reinforced by the sight of grain, and pecking at the grain is reinforced by grain in the mouth. At this point the chain of behavior blends into the physiologic and reflex responses of the digestive system, where a chain of reflexes continues to add to the reinforcing properties of the earlier stimuli. These conditioned reinforcements are the actual stimuli which are used to construct the chain of behaviors. To construct such a chain we begin with the last part of the chain that is already in the bird's repertoire. If the food is already familiar, the bird will peck at the grain when it sees it. When the bird is eating readily and adapted to the novel features of the experimental situation, the behavior of eating from a food dispenser is placed under the control of the magazine light and sound by presenting the food, along with the light and sound, only periodically. In the absence of the stimuli which accompany food delivery, the bird approaches the food magazine and the nonreinforcement of this behavior when the bird reaches into the empty food magazine reduces its frequency. After a small amount of training, the bird approaches the feeder only when the appropriate stimuli are present.

At this point, the light and sound accompanying the delivery of food are used to reinforce the behavior of striking the key by the procedure of successive approximation. The chain may be extended back indefinitely and new behaviors added by establishing the light behind the key as a new conditioned reinforcer. The bird's behavior is first brought under the control of the colored lights on the key by operating the food magazine only when the bird pecks at the lighted key. The lighted key may now be used as a reinforcer for a new arbitrary act such as pressing a treadle in the rear of the cage. At this point of development of the chain, the performance sequence would be as follows: pecking the unlighted key has no effect; pressing the treadle at the rear of the cage lights the key (The control by the unlighted key insures that the chain will not be short-circuited.); when the bird presses the treadle it changes the color on the key to the reinforced color; and the next appropriate behavior in the chain is pecking at the key which is reinforced by the magazine lights. Each stimulus serves as a reinforcer for a preceding response and a stimulus which sets the occasion for the next response in the chain.

Most operant behavior in both humans and animals occurs in similar chains. In human behavior many of the chains of responses consist of behaviors which affect a second individual who in turn provides the conditions for the next performance in the chain. Here the reinforcement for one response is the behavior of a second person which is a stimulus that makes possible the reinforcement of another response, leading ultimately to some major consequence.

Money is a major conditioned reinforcer in human affairs because it is a stimulus which makes possible the reinforcement of a wide range of important activities such as buying food and clothing. Technically, it is a conditioned reinforcer, reinforcing the performance preceding and setting the occasion for the subsequent response in the chain in which it functions. The chain may be very long. For example, money is the occasion on which an automobile can be bought; the automobile, in turn, provides the occasion on which the individual can now behave socially in a way which will make possible, perhaps, social reinforcements or earning more money. Other examples of important conditioned reinforcement in human behavior are attention and approval. As with money, these are reinforcing events because they represent occasions on which other behaviors may, in turn, be reinforcing. The likelihood of receiving a raise or a day off is higher when the supervisor is smiling than when he is frowning. The likelihood of getting a response to a question or some other request is much greater if the individual is paying attention than if he is not. These, then, function as reinforcers because they tend to be necessary conditions for the reinforcement of significant items in the individual's repertoire.

Additional topics

Human Behavior