The Nature of Intelligence
Chapter 9. The Sense Qualities
L.L. Thurstone
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Let us consider the fact that the energy of the stimulation of a receptor is not sufficient to account for the gross bodily adjustments of the organism. This fact makes it necessary to distinguish between two energy systems, one arising from the external stimulus and one with its source in the organism itself. These two energy systems should not be considered as hypothetical. Their existence is obvious in the fact that the amount of energy in the stimulus is insufficient to account for the bodily adjustments of the organism. These two systems are distinguished in several fundamental ways. The external system is insignificant in comparison with the internal system as far as the energy impinging on the receptor surface is concerned. The external system is fortuitous in its direction because its presence or absence to the organism depends largely on the direction in which the receptor surfaces happen to be exposed. The internal system is directed purposively for the needs and comforts of the organism as these may be realized at the moment. That cannot be said about the stimulus energy as such. These statements refer to the exteroceptors.
The interoceptors get their stimulation from the physiological conditions of the body and may be considered as serving the same rôle for the cerebro-spinal system as that
(129) served by the exteroceptors. Both the exteroceptors and the interoceptors give the cues for the cerebro-spinal machinery to be set in motion to bring about relief, and to satisfy the bodily needs.
If the stimulation touches one of the fundamental motives of the organism it will be keenly concerned and intensely conscious. The vitality of the organism supplies the energy necessary for making the gross adjustments in terms of the stimulation. It is in this sense that the stimulation acts like a trigger. The stimulation constitutes a minor energy system which releases the major internal energy sources of the organism to satisfy its wants. If the stimulation does not touch one of these .internal desires, nothing happens, and the stimulation is treated with indifference. It is for this reason that our reaction to a stimulation cannot possibly be stated wholly in terms of the stimulus. The main factors determining the response are the internal conditions of the organism itself. Of course we can say that, other things being equal, a large stimulus, a moving stimulus, an intense stimulus, will attract our attention more readily than a small one, a still one, a weak one. This is on the principle that, other things being equal, the large, moving, strong, and novel stimulation is likely to indicate future discomfort, failure, and even death. But other things are not equal except in the indifferent laboratory situation. It is true that we tend to remember the last few items in a list of nonsense syllables more readily than the items in the middle of the list. But our recall is determined far more by the consideration as to whether we care about the syllables. It is possible, then, to describe the reaction as a function of the stimulation to
( 130) a limited extent, if we make the assumption that the motivation is constant.
This reasoning applies readily enough to those situations in which we have a more or less conscious purpose immediately in mind. But it does not so obviously apply to those situations in which we relax and simply allow a sense-impression to register with an attitude of indifference on our part. Suppose that I am at this moment entirely calm and satisfied and that my mind is a more or less peaceful blank. I have no momentary purposes and I let my eyes turn more or less at random. Let us suppose that they fall on a glass paper-weight in front of me. I am conscious of the sense-impressions of reflected light from the glass cube. I have previously said that every conscious moment is an unfinished act, and this is true whenever consciousness serves its biological function. But in this case I am entertaining a conscious state, and I am sure that I have no purpose or action in mind. The sense-impressions are focal and yet no action is in sight or even intended. I prefer to consider these volitionally indifferent mental states as slight ripples of the internal energy system caused by the stimulation of a receptor surface. If the internal energy system, the degree of satisfaction of my various purposes at this moment, is in a state of equilibrium, it is still possible that the energy of the stimulation of a receptor may cause a slight disturbance of my internal calm. But if the stimulation is rather indifferent to my various motives, nothing will happen beyond the superficial ripple of awareness of the sense-impression. If the light which is being reflected from the paper-weight should be sufficiently intense to make
( 131) me uncomfortable, the stimulation would no longer be an indifferent ripple in consciousness because it would then constitute the cue in terms of which I would make some appropriate arm and hand movement to move the paperweight so as to regain comfort. The difference between these two situations is simply that when the stimulation is indifferent to my momentary purposes, it causes only what I have called a superficial ripple in consciousness. Such a slight disturbance from an indifferent external source constitutes sensory consciousness. It is in that state that we can discriminate between sense qualities. But when the stimulation touches one of our states of satisfaction we lend from our vitality the energy to attain satisfaction in terms of the sensory cue. It is in that case that the sensory cue is lived imaginally to its equivalent contact experience. It is then that perception serves in the rôle which is its normal biological justification.
I can well imagine a sincere objection to my analysis of mental life, which would run like this: " I am not so sure that my mental states are always unfinished actions. It is not entirely obvious that my purposes always start my thinking. The stimulus seems to serve as the starting-point for my conscious state right now when I am perceiving this indifferent object." I am granting that the stimulation from the environment may be primarily responsible for a state of awareness. But I am considering a mere mental state of awareness as biologically insignificant and only incidental to those more important situations in which the stimulation taps one of our purposes. When the stimulation leads to an adjustment, the stimulus serves merely as a
( 132) trigger to release the expression of my own purposes, the expression of my own larger energy supply. It is only that kind of stimulation which is useful for us. Indifferent awareness of sense qualities has no survival value. It is incidental to the situations in which the awareness of sense qualities serves a purpose. It is our capacity to particularize the sense-impressions to their equivalent expected contact experience, capacity to define our purposes in the form of expected experience even in the absence of the stimulation that constitutes intelligence. Purposeless awareness should be considered as a superficial ripple on consciousness, a moment of introversion, a slight disturbance caused by the action of the receptor, a trigger action which fails to release any motivation to act. If we should honestly note our sense-impressions during the course of a day we should probably find that the great majority of our percepts are actually looked for. It is relatively rare that a stimulus is not actually more or less consciously hunted for.
The sense qualities have received perhaps more attention from psychologists than any other psychological subject. If we study these sense qualities for the ultimate object of relating them to the functions of the organism as a biological unit, the study will be fruitful. This is in fact being done when sense-impressions are studied as means for space localization. As psychologists we are justified in being interested in sense qualities as such. We should not be impatient, however, with the general student who comes to us for instruction in psychology, to learn how the human mind works when it is actually working, to learn why people think, act, and live as they do. He is legitimately interested
(133) in motivation psychology. We should not expect him to be interested in the dynamically indifferent sense qualities as such. And yet we often devote the first and major part of our courses to this psychologically remote topic.
The ideal course in psychology for the beginning college student would be one in which the various human wants and desires are described as sources of conduct. These sources, in our present state of knowledge, would have to be described in terms of the types of behaviour and in terms of the types of satisfaction which they crave. It would not be necessary to insist that the description of these sources of conduct be entirely complete, or that the classifications be mutually exclusive. The main purpose should be to familiarize the student in an explicit way with what he already knows intuitively— the mainsprings of human conduct. It would do no harm to analyse the possible motives, conscious and unconscious, that may be exemplified in history, politics, the courts, literature, and biography. Complete agreement as to the sources and motives of conduct cannot be expected, but with continued study directed toward the sources of human conduct, experimental procedures for verification of hypotheses will eventually be forthcoming. What we need first of all is a shift of emphasis, a shift in the direction in which we look for explanatory categories in psychology, a shift from the mere description of the objective environment to a description of the individual himself and the satisfactions that seem to constitute his happiness. Merely to accomplish such a shift of interest in psychological teaching will immediately make it truly a study of the human mind. The quantitative point of view need not be discarded
(134) as the ideal scientific method, but its introduction into psychology has been forced to such an extent that we have found it necessary to leave mind in order to be quantitative. We have turned our attention to the measurable environment for the mere sake of being scientific and quantitative. It is more important for us to retain our true subject-matter, the human mind, even with pseudo-scientific methods, than to desert our subject-matter in order to be quantitatively scientific.
After the student has surveyed the field of human motives, he will be interested to see what happens to these motives when their expression is facilitated, frustrated, or inhibited. He will be interested to see how the human animal acts when several parallel motives clash for control, how motives seek substitute satisfactions, and how these substitute satisfactions can be consciously controlled by the individual himself and by public opinion. Then, for the student who specializes in psychology, further opportunity should be given to study the sense organs in detail and the physiological and neurological effects which are known to parallel the mental phenomena which are central for psychology.
