Psychology
Chapter 15: Reflex Action and Instinct
James Rowland Angell
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Motor Aspect of Conscious Processes.-- We come now to study the group of motor powers by means of which the psychophysical organism is enabled to guide its own movements, and so to control in a measure its own fate. In many of the discussions which have gone before it has been necessary to assume that these muscular reactions were occurring, but their intimate nature we have been obliged to overlook. As a matter of fact all the mental operations which we have analysed have their ultimate significance and their final outcome in precisely these motor activities. In reality, therefore, all our previous study has been upon these reactions, for it has all bad to do with their immediate psychophysical antecedents, which are functionally a part of them. Nevertheless, it is essential that we should examine the motor phenomena in and of themselves, and much more exhaustively than hitherto. We shall turn, first, to the earliest forms of muscular activity which we find in the human being, and then proceed to study the more highly developed forms which characterise a later period.
Primitive Motor Capacities.-- A survey of the motor equipment of a new-born babe discloses the fact, as we have previously seen, that a certain number of automatic and reflex coordinations are already provided for at birth. The automatic activities of respiration, circulation, and digestion are carried on from the first. The reflexes involved in sucking, crying, and clasping the fingers about objects placed in them
(284) also take place. But aside from these, the child's motor capacities are potential, rather than actual. This slender store of motor accomplishments finds its explanation in the undeveloped condition of the nervous system at birth.
Meagre as is this array of hereditary motor coordinations to which we have referred, it suffices, with parental assistance, to keep the child alive until the appearance of more adequate adjustments. Moreover, it bears striking evidence to the fact, were any demonstration of it necessary, that the human organism is exactly like that of the lower animals, whose instinctive activities are often sources of so much wonder, in that it possesses at birth preformed pathways in the nervous system, by means of which sensory stimulations may discharge in effective movements of accommodation. The primordial form of motor control over the environment is, then, so far as concerns the human infant, to be found in hereditary reflexes.
Early Motor Development.--Development goes forward at such a tremendous rate that it is difficult to follow with entire confidence the course of motor events during the first year or two of a child's life. But certain of the most important transitions from the conditions we have just described occur commonly during the first three or four months, and we may in passing profitably remark upon the general nature of this change. Afterward we shall go back to look for the appearance of other forms of automatic, reflex, and instinctive acts, which we have seen to be the primitive types of motor activity. We shall find evidences of their development at periods covering a considerable portion of the time of organic growth. Furthermore, we shall find that, in a modified form, the instincts remain throughout life as fundamentally important factors in the evolution of volition and in the foundation of character.
The point to which we wish to call attention for a moment is illustrated by the growth of the hand and eye control. At
(285) the outset the eyes are generally destitute of all orderliness of movement. They move independently of one another, and with no special reference to objects in the field of view. In the course of the first few weeks, however, they begin to move together, to converge, and gradually to show a tendency to follow moving objects. At this time the child loses its original blank stare, and from time to time fixates objects with a totally new expression of countenance. About the time that this accomplishment is achieved the hand begins to show a definite development. It explores objects with which it is in contact. The thumb, which at the beginning took little or no part in clasping, is now brought into operation, and the things grasped are moved about in a fairly well coordinated manner. The next step in advance is characteristic of all development in motor control, and consists in the conjoining of the two previously independent coordinations of hand and eye. The eye is now able to follow the hand, and the hand is able to give the eye objects for inspection.
We shall come back with more of detail to this type of intercoordination of acquired forms of control in our analysis of voluntary action. Meantime, it will be helpful to bear in mind that once a coordination, like the eye-coordination, is gotten under command, it is promptly incorporated as a member of a larger coordination, such as the eye-hand coordination, which is in its turn destined to a similar fate in the course of evolving conduct.
Turning back now to a fuller study of the instinctive and reflex types of action, we shall find the general trend of events to be somewhat as follows: 'The development of the nervous system goes on with astonishing rapidity during the first three years, so that the child has, with the exception of the sexual processes, practically a full store of reflexes established by the end of that time. Contemporaneous with this acquirement of the reflexes occurs the gradual unfolding of
(286) the life of impulse, and the upbuilding of this into the elaborate forms of voluntary action, which promptly tend to become habitual. We must now analyse more carefully the details of this process.
Reflex Action.-- A reflex act, as has been earlier remarked, is one in which a muscular movement occurs in immediate response to a sensory stimulation without the interposition of consciousness. Consciousness is often aroused by reflex actions, but the motor reaction is not executed in response to conscious motives, and in the more deeply imbedded reflexes consciousness is quite powerless to suppress the movement. Thus, in winking we may be conscious that the eyelid has closed, and at times the movement may be executed voluntarily. But if a cinder or other irritating substance enter the eye we may be wholly unable to resist the tendency to shut the lids. On the other band, when we are absorbed in reading our eyelids may close dozens of times in the reflex way, without our b ecoming in any definite manner aware of the fact.
Variability of Reflexes.-- We have already referred many times to the (racially) hereditary nature of these reflexes. It remains to point out certain other striking facts about them. In the first place, they are subject, like all organic activities, to the general principles of development. They appear from time to time, as the nervous centres ripen, and are not all given complete at birth. The more rudimentary of them appear within the first few months. Sneezing, coughing, and hiccoughing come within the first few days, as a rule. Winking comes somewhat later, generally from the seventh to the eleventh week. Walking, which is primarily based upon reflexes, does not ordinarily begin until the twelfth to the eighteenth month or thereabouts, and is generally preceded by the creeping movements, which are probably partially reflex. Moreover, no one of the reflex acts is, at the outset, so well coordinated as it speedily becomes. It
(287) is clear that the nervous machinery, like other machinery, requires to be used somewhat before its maximum efficiency is available.
Furthermore, the reflexes vary at times in response to the general conditions of the organism. They are not wholly dependent in their operation upon the presence of a stimulus. The child, for example, when sated, stops sucking. When one is nervously wrought up, a slight noise, if unexpected, may result in a violent movement; whereas, if one had been agreeably absorbed in some occupation, no movement of any noticeable kind would have occurred. On the other hand, the essentially mechanical nature of the reflex is rendered obvious by the impartial way in which such responses are often executed, regardless of the desirability of the act at the moment. A man wishes his presence to be unobserved when in a dangerous situation, and he must needs select that occasion to be seized with an irrepressible paroxysm of sneezing. Again, although one is behind a strong screen, one still finds it impossible to avoid winking when any threatening object is seen approaching close to the eyes. It appears, therefore, that whereas the reflexes represent hereditary modifications in the connections of sensory-motor activities,-- which are undoubtedly indispensable for the maintenance of organically useful reactions,-- they may at times, by virtue of their mechanical nature, react in injudicious ways; and on the other hand, certain of them are unquestionably open to modification, either through the direct control of consciousness, as when one succeeds in suppressing a tendency to wink, or through the indirect effect of general organic conditions. It is evident, therefore, that reflexes represent various degrees of plasticity, but this does not invalidate the doctrine that all of them are hereditary in nature, and that on the whole they contribute distinctly to the general efficiency of those adaptive reactions which the organism makes upon its surroundings.
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Instincts.-- Instincts have an origin unquestionably similar to that of reflexes. They represent structurally reformed pathways in the nervous system, and stand functionally for effective inherited coordinations made in response to environmental demands. It is, perhaps, impossible to draw any absolutely sharp line between instincts and reflexes, although many principles of demarcation have been proposed. On the whole, the most fertile and suggestive working distinction seems to be found in the presence or absence of some relatively definite end dominating a series of acts. If the motor activity is simple, and is discharged in response to some objectively present stimulus, without conscious guidance, it will be safe to call the act a reflex. Moreover, some reflex acts are essentially unconscious, whereas instincts, in the higher animals at all events, appear always to involve consciousness. Instincts accordingly depend more largely than reflexes upon the operations of the higher brain centres. If the activity involves a number of acts, each one of which, considered singly and alone, is relatively useless, but all of which taken together lead up to some adaptive consequence, such as the building of a nest, the feeding of young, etc., it will be safe to call the action instinctive. The difference thus pointed out is founded theoretically upon the nature of the functions subserved by the two types of action, their relative immediacy, generality, etc. It sometimes reduces in practice to a mere difference apparently of degree or complexity, and will be found on further examination to involve, generally at all events, a difference in the intra-organic conditions leading to the two forms of reaction. It must be frankly confessed, however, that many cases are discoverable in which all distinctions seem arbitrary and fictitious. Too much stress should not be laid, therefore, upon the matter of ultimate differences. It is rather upon the identity of service to the organism that the emphasis should fall, with the added recognition that such service may be rendered in
(289) thousands of ways, whose interrelations may well baffle our clumsy and ill-informed attempts at classification.
Modifications of Instincts.-- Instincts resemble reflexes in their susceptibility to modifications through experience, and also in their appearance in connection with definite stages in the development of the nervous system. Experience operates in two opposite directions. If the first expression of an instinct chances to be disastrous, and results in pain or fright, the instinct may be either temporarily, or permanently, inhibited. Thus, chicks, which possess the instinctive tendency to peck at food, are said to suppress this tendency when bad-tasting food is given them. On the other hand, if the instinctive action is successful and produces agreeable organic results, it tends at once to become ingrained as a habit. In all creatures which possess even rudimentary forms of conscious memory instincts must, therefore, speedily lose their original and wholly blind character. The tendencies to instinctive reactions must, in such creatures, very early set up organic reminiscences of the previous consequences of their indulgence; and these reminiscent traces must lead either to inhibitory movements or to responses of the habit type, in which the outcome must be in some vague way forecast.
Suppression of Instincts.--Instincts not only appear at definite points in the growth of the nervous system, but certain of them may also atrophy and disappear, provided that at the crucial period the appropriate conditions are not at hand to call them out and fix them as habits. Illustrations of the periodic nature of development in instincts are familiar to everyone. The puppy cannot swim, the older dog can, and he does it instinctively. The bird displays no tendency to nest-building until a certain maturity is attained, and instances of a similar kind might be multiplied indefinitely. The abolition of an instinct by failure to secure expression at the correct time is shown in the case of chickens, which tend at first to follow any moving object. Ordinarily nature
(290) provides, of course, that this object shall be the maternal hen. If the opportunity to translate this instinct into a habit is not afforded, the instinct dies within a few days, and thereafter commonly cannot be reestablished.
Instinct, Experience, and Reason.-The relatively flexible and plastic nature of instincts which is suggested by the foregoing observations Ends additional confirmation in the innumerable instances in which intelligence, or unexpected and unusual environment, come in to exercise modifications. In the earlier views of instinct we always find it contrasted with reason, as though the two were radically distinct. The keener insight of our own time shows us that although reason represents the individual's contribution to his own fate in terms of his own experience, while instinct represents the contribution of racial experience, the actual operation of the two factors often displays most intimate interrelations. This is peculiarly true of all the higher animals, and especially man. Indeed, the great difficulty in studying instinct in human beings is due to the fact that intelligence immediately comes in to transform the native reactions in accordance with the dictates of the individual's personal experience.
Even in the lower animals, however, individual experience exercises a guiding Influence over the particular forms of instinctive expression, although in many of these cases we must speak very conservatively as to the manner and measure in which consciousness participates. Whatever the explanation of the modus operandi, there can be no doubt that birds and insects such as bees and wasps and ants often modify their instinctive methods of nest-building in a most remarkable manner when the exigencies of local conditions require such modification. On the other hand, instincts are often carried out in a bungling fashion, and in the face of circumstances clearly fatal to their successful issue. The well-known disposition of certain dogs and squirrels to attempt,
(291) with elaborate efforts at digging, the burying of their bones or nuts when confined upon hard board floors illustrates the occasional futility of irrepressible instincts. The classical observations of the Peckhams upon bees and wasps afford striking instances of instincts misdirected at some crucial moment. They report, for instance, that wasps frequently prepare a nest carefully for the reception of the food store and then seal it up empty.
The obvious implication of such observations is that we have to do in the phenomena of instinct, as these appear in the several genera and species of the organic kingdom, with an overwhelming variety of reactions, all of which evidently emanate from the same type of ancestral source; but with indefinite and unpredictable susceptibility to modifications from environing conditions, and with an equally uncertain submission to conscious guidance. In so highly evolved a nervous system as that possessed by the human being we may naturally anticipate a very considerable Dumber of these ancestral tendencies, and we must also expect to find them very promptly submerged in motor activities under the control of consciousness. These expectations seem to be fully realised by the actual facts.
Origin of Instincts.-- Although everyone is agreed that instincts are racial habits transmitted by heredity to the particular individual, there has been wide difference of opinion regarding the precise manner in which they originally became established. The questions here at issue are clearly in large part biological in nature, and this is, therefore, evidently the reason why we find that the authoritative names connected with the conspicuous theories are chiefly those of great naturalists. Two fundamentally opposing views have until recently held the field. One is commonly known as the theory of lapsed intelligence. The American biologist, Cope, was an eminent defender of this view, which regards instincts as organically fixed habits which were originally in-
(292)-telligent adaptive acts partaking of the general character of volition. Wundt has been a distinguished adherent of this view among psychologists. The second theory is known as the reflex theory, and its basal contention is that instincts are simply accumulated reflex adjustments, explicable in their survival by the general principle of natural selection, which tends to weed out accumulations, however acquired, which are not preservative in their effect. Spencer and Weismann are representative adherents of two sub-forms of this theory.
The first theory has been criticised as making too great demands on our credulity concerning the amount of intelligence displayed by primitive forms of consciousness, and also on the score of defective evidence for the transmission of acquired characteristics. The second theory has been held vulnerable in its inability to explain how groups of reflex movements could have been slowly built up, when only the final step in the process rendered the chain really useful. A recent modification of these views, for which J. M. Baldwin stands sponsor among psychologists, is known as the theory of organic selection.
Theory of Organic Selection.-The crucial point in this theory is the supposition that even tentative and imperfect accommodation, with or without conscious direction, may serve to preserve the life of a species during the critical period when the instinct in its entirety is forming, and thus give it opportunity to become permanently imbedded in the organism as both a structural and functional attribute. Whether this view succeeds in weathering the storms of criticism or not, it is at least a highly ingenious and suggestive modification of the two previously extant views. It seems to contain what was most significant in both, while avoiding the more obvious pitfalls belonging to each. It gives scope for the play of intelligence in assisting in the formation of useful reactions, without going to the indefensible extreme of
(293) assuming that all valuable coordinations have had such intelligent origin. On the other hand, it offers a practicable hypothesis as to the manner in which movements of essentially reflex character may have been become chained together in instinctive reactions.
Function of Instinct. -- Despite the differences which have characterised the opinions of the most acute biologists as to the origin of instincts, there is no divergence of opinion as to their function. They represent, by common consent, those forms of reaction upon the environment which the race has found most effective in maintaining itself against the rigours of climate and geographical habitat, and against the assaults of various forms of animal life. So far, therefore, as we may find traces of true instincts in human beings, we may know that we are confronted with tendencies which represent racial experiences, with reactions which express the pressure old ages of men engaged in the struggle for existence of untold It should, in the light of such considerations, afford us no astonishment to find that some reactions have been preserved, which are either useless at present or even somewhat positively disadvantageous. Moreover, remembering the complex conditions of our organic structure, we may well expect that certain of these instinctive reactions may possess their chief value and significance in the intra-organic physiological changes which they bring about, rather than in movements primarily affecting objects in the environment. Both these anticipations we shall find fulfilled.
