Types Of Verbal Behavior
The simplest form of verbal behavior, present in even the very young child, is similar in its dynamic function to the behavior of a pigeon pecking a key or a rat pressing a bar. The similarity of the two cases is more apparent if a student is substituted for the pellet delivery mechanism in the case of the pigeon. In both the vocal situation (the child) and the nonvocal situation (the pigeon), the organism's response produces a discriminative stimulus that is the occasion for a second individual, in turn, to provide a reinforcing stimulus within the required temporal limits and relative to the current level of deprivation. The child asks for toast, the pigeon pecks the key, and the parent and student experimenter deliver a piece of toast and a portion of grain, respectively. The mediation of the second individual, the parent or the student experimenter, is important only if his special characteristics influence the nature of the behavior that will be reinforced. With the pigeon, the experiment is arranged so that the characteristics of the individual who delivers the reinforcement have minimal effect. The depression of the switch behind the key at which the pigeon pecks gives the student an explicit criterion by which he can determine whether or not to deliver the pellet. With the child, the motive for the parent's behavior is such that no such explicit criterion exists for delivering the reinforcer, and almost any condition affecting the parent will influence the reinforcement of the child's demand. Some examples of these conditions might be prepotent responses such as answering the telephone, going to the door, or reading an absorbing magazine or newspaper. If the reinforcement of the parent's giving toast is the termination of the aversive stimulus by the child, the probability of reinforcement depends upon how aversive the child's request is to the parent. This aversiveness, in turn, is a function of the general conditions of the parent, how frequently the child repeats the demand, and the tonal quality and intensity of the demand. However, a psychologic analysis of either the child's behavior or the pigeon's is that of an operant response reinforced by its consequences with a reinforcer relevant to the current level of the speaker's deprivation. The frequency with which the pigeon pecks the key depends upon its level of food deprivation; the child's response of asking for toast depends upon when it has last eaten.
This form of verbal behavior, which Skinner describes by the term mand, is the most easily developed and maintained kind of behavior in the verbal repertoire. The early, undifferentiated crying of the child that occurs because of its operant effect on the parent is a mand. Even in human behavior, the mand is not necessarily vocal in form. For example, the child may tug at the sleeve of the adult in the direction of the cookies on a high shelf, or he may raise his arms to be picked up, or he may point at an object that he desires. In cases of incomplete or minimal verbal development, as, for example, in extreme forms of childhood psychoses, verbal mands may be present even when all other kinds of verbal behavior are absent. Many times the verbal repertoire is so minimally developed that it contains no vocal forms. The mand is usually some nonvocal form, such as kicking on the exit door at mealtime or pulling at the pocket of the person who usually gives candy.
The mand is under close control of the level of deprivation of the speaker because of its nearly immediate reinforcement. Therefore, its continued maintenance depends upon a listener who is disposed to provide positive reinforcement. Such a disposition to reinforce the mand may come about because of aversive control by the speaker, as, for example, the tantrum or threat of tantrum by the child. Or it might occur because of the complex conditions derived from the individual's social or phylogenetic history that would make it reinforcing for a parent to positively reinforce the behavior of the child. In the growth and development of the child, the mand is progressively differentially reinforced in the direction of forms of vocal responding that conform to community practices. In the very young child, the form of the mand is usually greatly distorted from usual community practices. For example, he says "gee-gee" for milk and "wah-wah" for water. As the growing child is capable of a wider range of vocal sounds, the parent tends to shift his reinforcement in the direction of the vocal form most closely approximating the community practice and to extinguish the older, less adequate forms.
In an echoic repertoire, there is a formal identity between the response produced by the speaker and the discriminative stimulus which is the occasion for the response. For example, the adult with a fully developed echoic repertoire can repeat any word he hears. Once he develops an echoic repertoire, the individual has effective means for instantly developing new, complex responses. It is no longer necessary to successively approximate or differentially reinforce new complex verbal forms. In the growing child, for example, the parent or school community can generate new verbal responses in the child simply by saying, "The word for this object is ---." The echoic process reaches its culmination in the high skill of the mimic, who can not only imitate the essential characteristics of the verbal response required to have its main effect on the community but also imitate the smallest detail of pitch, intonation, and pronunciation so that the response is practically a mirror imitation of the stimulus. Such a repertoire is technically called a fine-grain repertoire, because every element in the stimulus controls a corresponding element in the imitator's response.
The parrot has this fine-grain repertoire. However, the parrot is not necessarily born with the capacity to imitate. More likely this bird inherits the capacity to be reinforced by a correspondence between its response and the auditory stimuli it hears.
We do not know the extent to which the human infant inherits a disposition to be reinforced by a correspondence between a heard stimulus and his vocal productions. Nevertheless, the repertoire develops, in any event, as a result of specific reinforcing practices of the child's community, which in general has a strong interest in developing echoic repertoires. The young child is continuously asked to repeat words, and his reinforcement depends on how closely he approximates at least those elements required to define the community verbal practices. As the child is repeatedly reinforced or nonreinforced, as his verbal response corresponds with the verbal stimulus or does not correspond, he gradually acquires a general repertoire based on the abstraction identity. The echoic repertoire is very similar to that developed by the reinforcing practices associated with higher than, lower than, larger than, and smaller than. The explanation of the process is identical with that described earlier. For the concept or abstraction triangularity, a large variety of stimuli are presented, and a response is reinforced in terms not related to the properties of any one stimulus but of an abstraction relating to all. With triangularity, the concept is the number of sides in the figure and the relation of the angles; in identity, it is the point-to-point correspondence between the elements in the two objects or events. As with most complex repertoires, the echoic repertoire is successively approximated by the parent. At first, any loose approximation to the stimulus is reinforced. Later, the community becomes stricter and accepts only those verbal forms which satisfy the reinforcing practices of the broader community. The dictionary, for example, is one specification of The dynamics of an echoic response are very different from those of the mand. For the mand, the most important single variable was the level of deprivation of the speaker and the relevance of the reinforcer to this level of deprivation. The reinforcement of the mand is clearly of primary benefit to the speaker rather than the listener. The reverse is true with the echoic response, however. Although the ability to repeat any word may be of ultimate benefit to a speaker, the ability to mimic words is clearly of more benefit to the listener than to the speaker. The echoic repertoire is a means by which the community may enlarge the ,child's verbal repertoire for the long-term rather than the immediate benefit of the child and community. Clearly, the development of an echoic response is more related to the strength of the listener's behavior than that of the speaker. As a result, it depends upon a conditioned reinforcer such as the generalized reinforcement of attention or approval.
TACT An important extension of verbal behavior occurs in the development of the tact. For example, on the occasion, "What is this?" the child answers, "Chair." The child reports, "It's raining out" or "The mailman is coming;" or the student says, "This is the axon of the nerve cell." In each of these cases, a verbal operant response is reinforced only on specific occasions. The response "Chair" is reinforced only in the presence of a chair, or in the presence of some other occasion consistent with the reinforcing practices of the community. The reinforcement of the child's verbal response about the rain or the mailman depends upon what happens when the parent goes to the door, or when she puts on a raincoat. If there is, in fact, a mailman, the child's original verbal response will be reinforced by "Thank you," or some similar expression of approval. Simply seeing the parent emit some reinforcible behavior based on the child's report may, of itself, serve as a reinforcement for the child's response. Not only will the child be reinforced for responding discriminatively to various parts of his environment, but he is also likely to be punished if his verbal responses do not conform to the community's normal reinforcing practices. If, in fact, no mailman is present or if it is not raining, the stimulus presented to the parent will result in nonreinforcement of parental behavior and is likely to result in punishment or, at least, mild disapproval.
In its basic form, the tact is simply a discriminated operant. The child who learns to say, "Red," in response to an object emitting light of the required wave length has acquired this behavior in a manner almost identical with that of a pigeon which pecks at one of four keys labeled red, green, blue, or yellow, depending upon a colored sample that is presented. The critical operation is the same principle of stimulus control discussed earlier. A response reinforced on a particular occasion and unreinforced on other occasions soon comes to have a high probability of occurrence in the presence of the stimulus which is the occasion on which it is reinforced. The child is exposed to constant differential reinforcement as the parent presents some object and asks, "What is this?" Much of school work is concerned with adding tacts to the child's repertoire: What is the capital of England? Who invented the telephone? What happens when HCL is added to Ca(OH)2?
The essential nature of the tact, however, is different from the pigeon's behavior in its relation to the broad social community.
The Tact Benefits the Listener. The ultimate value of a tact to the listener in the verbal community is an occasion when the speaker has access to stimuli not immediately available to the listener. For example, the parent asks, "Who is at the door?" From his vantage point at the window, the child replies, "The mailman." The child's verbal response in this situation gives the parent access to stimuli which would be otherwise unavailable, and the parent can now be influenced by the same stimulus as the child, even though she does not have direct contact with it. The significance of the critical element in this episode is that both the parent and the child have the same general behavioral repertoire in respect to spoken, heard, and seen mailmen. The stimulus control of the child's behavior is maintained when the parent reinforces the child, that is, if in fact she sees a mailman when she comes to the window or finds mail in the mailbox. In this way, the verbal community insures the close correspondence between the verbal behavior of the speaker and the reinforcing practices of the community. The correspondence between the practices of the speaker and the listener are not inevitable, as, for example, when the boy cries, "Wolf," or when the very young child teases the parent by reporting the presence of someone when in fact no one is there.
The dynamic characteristics of the tact are in contrast with those of the mand, which is reinforced without special regard for community reinforcing practices and is largely a function of the speaker's current level of deprivation. In the mand, the response is emitted largely for the benefit of the speaker, and the characteristics of the listener enter only insofar as a reinforcer relevant to the speaker's level of deprivation may be forthcoming. The form of the behavior of the child who is asking for candy or the occasions on which the behavior occurs are largely influenced by what forms of behavior are more likely to produce candy. The characteristics of the listener influence the child only to the extent that they influence the probability of the child's behavior producing candy. However, the maintenance of the tact depends upon its usefulness in the behavioral repertoire of the listener.
Reasons for the Tact. The community has a large investment in developing tacts in the child because the tact is the major means by which social interchange may take place. Scientific knowledge, for example, consists largely of tacts which are verbal stimuli prescribing behaviors involving the subject matter of the science which will have specified effects in the physical environment.
Correspondence between the Stimulus and the Verbal Response. The community has a large investment in insuring a close correspondence between the controlling stimuli and the related verbal responses. In the example of the boy who cried "Wolf" there is a breakdown of the controlling relation specified by the community between stimulus and verbal response. In the ideal situation, from the point of view of the community's advantage, the tact is solely determined by the relevant stimuli specified by the community's reinforcing practices. Scientific procedures are essentially technics of self-control on the part of scientists to insure that the verbal stimuli (the reported result of the experiment) will strengthen the same behavior in the listener and be reinforced by the same environmental consequences as for the speaker. The scientific community has a large investment in being sure that the scientific report is solely under the control of the experimental finding and not some disposition of the scientist based on an irrelevant variable, such as a prize or promotion.
Because a verbal response is rarely, if ever, controlled by a single variable, a completely pure tact is virtually impossible. Part of the "impurity" arises because the community practices with regard to when verbal responses are appropriate are, of themselves, imprecise. For example, the distinctions between a table and a desk may be blurred considerably, even to the point where either word is appropriate.
Because the tact is largely for the benefit of the listener rather than the speaker, the use of a generalized reinforcer is the essential factor in its development. Reinforcing verbal responses by a generalized reinforcement is, essentially, providing a long chain of responses in which a verbal response of the speaker is reinforced by the approval of the listener. The listener, in turn, by his approval of the speaker, may provide reinforcing consequences for other items in the speaker's repertoire, as, for example, reinforcing mands. Because the generalized reinforcer is a conditioned reinforcer which is effective without regard for any specific level of deprivation, it may be used to strengthen behaviors which have no immediately reinforcing consequences to the speaker. Without the generalized reinforcer the verbal behavior of the speaker would be limited to responses terminating, avoiding, or reducing aversive stimuli. The generalized reinforcer may be considered as a way to defer or delay reinforcement of behavior by providing a conditioned reinforcement which in the past has been associated with the continued reinforcement of a large number of items in the child's repertoire that have been associated with a large number of deprivation conditions.