Sensory Drives

Thus far we have taken into account the two main groups of effectors. Under the term visceral we have included the patterns centered in unstriped muscles and glands. Under activity needs we have included the system that involves the central and peripheral nervous systems discharging into the striped muscles. But the story is far from complete. One of the great dangers threatening an adequate personality psychology is the failure to achieve an adequate balance, through neglect of sense perception and other cognitive functions. Personality is as much a way of becoming sensitive as it is a way of reacting upon the environment. It is as much a matter of selecting and using outer energies as it is of focusing activity. The little child spends a large part of his time exploring with his senses, pursuing sights and sounds and touches, often carrying the activity forward for a brief period after the sensory stimulation is gone-the beginnings of exploratory behavior. The sense organs and the brain regions with which they are connected stand ready to act and are healthy only when allowed frequent action.

As we saw above (Chapter 4), there are large individual differences in such receptor functions and in the affective responses linked to them. We must now go further and stress that since such affective differences exist we must, if we are to be consistent, say that sensory needs or sensory drives differentiate individual infants. This is the implication of the marked individual differences which infants show in their responses to taste stimulation. It is also the basis of the work done on sensory toys, such as cold cream, dough, and finger paints, in which great differences in delight are shown by children playing with these various tactual and kinesthetic stimuli. These differences appear extremely early; they are like the sensory drives which differentiate one puppy from another. They appear to remain rather stable for individual children, at least during the period of nursery-school observations. There is a prima-facie case, then, for sensory drives cognate in importance with activity and visceral drives, and there is evidence that from the very beginning the intensity of such needs shows a highly individual character. It should be added that many studies of musical prodigies indicate an extremely early sensitiveness to tone that is quickly elaborated by any opportunities afforded for musical training, producing in a few years results which most people cannot achieve even after laborious efforts throughout the entire growth period.

The neglect of sensory drives has been largely due to the effort to place all the real generators of activity in the viscera. But even in studying the visceral drives one keeps bumping into sensory factors of various types. The most pertinent example here is a study by David Katz, or rather a twin pair of experimental studies. In the first experiment, a group of hens eat all the grain they can hold; they are taken to another room where other hens are eating from a large pile, whereupon they immediately start eating again and consume a great deal. In the second experiment they are fed all they will eat of grain that has been artificially colored red; complete satiation is evident. They are then given some of the same grain colored green, and again they proceed to eat a large quantity. Is it hunger that is satisfied in the first instance? It hardly advances our understanding to say that the first behavior is pure hunger behavior and the second pure sensory stimulation. The hens eat as actively in one case as in the other. Sensory stimulation is a major source of activation of tension levels. In fact, if the term "sensory" is used as it should be--to include all the different sensory impulses, including those from the alimentary canal--it is the only source. Féré understood this when in illustrating the principle of dynamogenesis he showed that any flash of color, any touch, any sound increases the force of the grip upon the dynamometer. In all hunger situations there are external as well as internal stimuli; summation of stimuli is always the rule.

It is likely that the principle of the conditioned response is of some help here; i.e., the hens have been conditioned to eat because they have eaten in situations where they saw other hens eating. But this again does not advance us far, because conditioning is itself a case of the summation of stimuli (the preparatory facilitating phase shows this), and because stimuli to which the hens have not been specifically conditioned--new grain colors and even revolver shots--increase the intensity of many drive patterns. If this is true, there can easily be complete satiation of an activity, yet immediately thereafter a continuation of the activity when there is an increase in the tension level. And this increase may arise either directly from a local agency acting on the tissues primarily involved, or secondarily through raising tensions elsewhere which are communicated to this primary center. Satiation, then, is always relative; or, to speak more accurately, the question is one of the total field situation, in which the internal dynamics and the quality and quantity of external stimulation must be fully considered. The fields stretch out from the tension center and comprise not only other bodily tissues but all the interacting forces observed within the behavior pattern.

The manner of envisaging the whole problem of the sources of motive has never, perhaps, been described so well as by Diamond, who made clear the misunderstanding of the evolutionary theory which led us to put primitive things at the apex, when actually the evolutionary implications tend to indicate that the more complex structures and functions would never have evolved had they not served a new function different from and sometimes dominant over the more primitive ones. Thus he was able to show that needs for intellectual, esthetic, and other individual and social activities may arise, simply and naturally, from the way in which the human nervous system is constructed and from its interrelations with the rest of the body. From this point of view the music of songbirds, the curiosity and playfulness of chipmunks and kittens, the self-decoration of primates find a phylogenetic place, with science, invention, and art as the natural and necessary products of the sheer process by which complicated functions have led into still more and more complicated functions. The Freudian view that redirected, sublimated sex energies are the source of such activities becomes unnecessary and is seen in its historical perspective as another attempt to Darwinize at a time when Darwinism as a system was conceived to mean the direct derivation of complex processes from simpler ones without recognition of any elements of genuine novelty or any expressions of true emergence. Sexual, aggressive, and other energies may indeed lead to indirect rather than direct expression, and they may be combined with other motives; but the more complex behavior patterns of complex organisms are genuinely functions of their complexity, not merely new revelations of the simpler energies. And when once these complex types of response are possible, they tend to become selfperpetuating through the use of a larger and larger share of the energies available to the organism.