Imperfect Stimulus Control

There is considerable variation in the degree of precision of control by the environment over the behavior of the organism. By the very nature of discriminative operant control, behavior frequently occurs on occasions when it can not be reinforced. The errors and incorrect responses of the student as he acquires a new repertoire are such examples, as are many of the common slips and errors which occur daily in the repertoire of the average person. Many of the conditions responsible for the inappropriate emission of behavior are known, but most have not yet been analyzed. Even in normal behavior, the control by the environment over the individual's behavior is, at best, approximate in many areas. We misspell words, use the wrong key in the lock, reach for the incorrect tool, and make mistakes in arithmetic or in solving algebra problems. In psychotic behavior, there is often a complete breakdown of the relation between the verbal responses of the individual and their appropriateness to the environment in which they occur. When we fantasy ourselves "winning the field" these are responses which are relevant to a state of deprivation but not to the current environment. The psychotic frequently emits verbal responses which the normal verbal community will not reinforce. Hallucinations and fantasy represent an extreme breakdown in stimulus control in which verbal responses are emitted in the absence of the occasions on which they were customarily reinforced. When a man says, "The chair is a bear who will soon attack," the essential fact is that this is behavior which the community does not reinforce. On this occasion, the response, "the chair," is not one which the community accepts; similarly, when a person reports that there are mice in his stomach or that all of the personnel of the hospital are trying to poison his food. On the other hand, large parts of the discriminative repertoires are under perfect stimulus control, particularly in dealing with the physical environment, as in eating, walking, or lifting objects. In many cases, the gross behavior of an individual will be under good stimulus control while the related verbal behavior will be under defective stimulus control.

Brady and Lind (1961) found such a situation in their work with a hysterically blind man, who although blind by almost any conventional diagnostic test, successfully evaded objects in his path which could not have been detected except visually. Here, as with other distortions in stimulus control, variables other than the usually relevant stimulus determine the individual's response.

Multiple Determination Of Discriminativeresponses

A given stimulus, as well as the related reinforcing practices of the community, is only one of the variables which control an individual's response on a particular occasion. The clinical concept of secondary gain is an example of the multiple determination of a discriminated response. The hysterically blind person who successfully evaded objects in his path is clearly talking about his environment inappropriately when he reacts to and describes situations as if he were blind. What may frequently happen in such cases is that the verbal repertoire which indicates blindness is reinforced by enabling the patient to avoid other environments which are extremely aversive and in which one must have vision in order to function. Being blind may serve as an avoidance response.

Under extreme conditions of deprivation, the normal controlling relationship between a stimulus and community practices may break down completely, even in an otherwise normal person. Someone on the desert under extreme conditions of water deprivation may see water when none is there; and the lonely man in a strange city may see faces which strongly resemble people he has known. It is a maxim of clinical psychiatry and psychology that the patient's verbal report does not necessarily reflect the obvious condition to which it appears related. The conditioned aversive stimuli generated by a punishable verbal response are significant factors in altering a verbal response from the form in which it is normally emitted. Sometimes an emotional state will distort the usual form of response. An example is the anecdote told by Skinner in which a woman, speaking at a prohibition rally, who had never before used a microphone, said that she had never before used a speak-easy.

Whether the psychotic really sees the bear or knows that a chair is present rather than a bear is a further problem, involving a private event accessible only to the individual. This problem will be discussed later in more detail, but for present purposes, the important issue is that most behavior is under the control of special features of the environment and is a function of many conditions, but the degree of control varies in precision. An individual may or may not be able to notice the distortions in his verbal behavior produced by secondary processes. Some of these where the individual is unaware (unconscious) are called Freudian slips. At the one extreme is the scientist's behavior which is closely controlled by particular stimuli and the relevant reinforcement contingencies and, at the other, the very imperfect conformation between the verbal behavior of the psychotic and the responses ordinarily reinforced by the community at large.