COMPARATIVE PSYCHOLOGY. Comparative sciences generally are concerned with the co-ordination of differences in a common subject matter. Comparative psychology attempts this task in the world of Mind. Now in the expressions of mental activity the range of difference is enormous, extending from very low phases of animal life to the highest achievements of civilized culture, and all these differences must be regarded as significant for the student of Mind and its function in the world of life. Are we then to infer that they all belong to the field of compara tive psychology? A critic will object that this would be to create an impossible science. The study of culture, for instance, is sociological or historical. It requires quite different methods from those of the study of an ape or a beetle or a decerebrated frog. We must in mere mercy to our student put a limit. Shall we then say that the concern of psychology is with faculty rather than performance? The difficulty here is that in the last resort faculty can only be measured by performance. Thus a popular explanation of the immense divergencies of human culture refers them to what is known as racial psychology, i.e., to supposed inherent differences in the faculties of different races. Psychology can only test this supposition by calling in the aid of sociology to determine how much difference can be effected by the cumula tive effect of social inheritance, operating on a common ground work of capacity. But it cannot wash its hands of the problem. Whether through some extension of innate faculty or through the social causes suggested, the actual achievements of thought are indutiably greater in the civilized than in the uncivilized world, and the function of Mind in the direction of life proportionately enlarged. The significance of mental development would be missed if these chapters in its story were cut out.
Nevertheless, the student, forced to economize his energies, must limit his field. He may hope to become an expert in one method, but not in a dozen, so he chooses one for his speciality. Unfortunately the demands of specialization are progressive. He might choose, say, animal psychology as his field, but there is still an immense difference between the study of chimpanzees and that of starfish, an immense difference between the methods of a physiological laboratory, which may be applied to any animal and to man himself, and those of the systematized observation of the normal animal. Cruelty barred, all methods are legitimate, but it is a familiar fact that he who follows one exclusively will tend to take that one alone as the universal solvent. Now it is precisely the business of the comparative psychologist to accept evidence from all quarters and all methods, and try to piece them together into a coherent whole. We cannot then make any such division as would destroy the unity of the comparative view, but we may recognize that with development methods change; the changes determine the lines of specialization.
Behaviour and Behaviourism.—In all fields the principal data are contained in behaviour. This is easily seen in regard to the higher fields, as soon as we recollect that the use of words and therefore the writing and reading of books, to say nothing of the execution of works of art, are forms of behaviour. In the last analysis the phenomena of our own consciousness are also the be haviour of those complex wholes which are ourselves and this radi cal Behaviourism is the one and only method of all psychology. It is also the one and only method of physical science, for if Mind is the unity which we conceive to run through certain forms of behaviour, so Matter is the unity which runs through other forms of behaviour. This truth is now fully recognized in physics, which conceives matter as a form of energy. Radical behaviour ism applies impartially to "matter" and "mind." The world of our experience is material in so far as it acts in certain generic ways known roughly to commonsense and more elaborately to physical sciences. But we also find many objects, which while behaving in some ways like matter, being e.g. visible and tangible, neverthe less reveal differences which are the more striking the more rigidly physics delineates the material world as essentially indif ferent in all its changes to the later outcome of such changes. For throughout the world of living things we find behaviour so correlated with circumstances as to contribute to the mainte nance of an individual organism and its race, and among many organisms we find the correlation wider, more efficient, and mak ing not only for racial life but for certain qualities of life. The factors at work in this correlation are many, but there is some thing running through them all which stands in marked contrast with our conception of matter and we call it generically Mind. It is still for psychology to give more precision to that term, as it is for physics to give the precision to the conception of matter. And it is for philosophy to explain how one and the same reality can exhibit these differences of aspect.
What is at present known as Behaviourism would sweep the whole field of direct consciousness out of psychology in the name of the strict requirements of observable fact as a basis of science. We do not know what facts we observe more directly and im mediately than that, for example, we are sometimes cold or hot, angry, pleased, grieved or joyous. But, says the behaviourist, all these are physical states. That is a confusion between e.g., a sensation and its stimulus. Science has only two rules about observation. One is that our inductions must be founded on it, and the other is that we must treat all observations impartially.
At the same time, it should be recognized (a) that introspec tion as a technical method is full of difficulties which increase with refinement; (b) that when we come to beings not altogether like ourselves, and with no language to correct our errors, the imputation of processes like our own is risky, and in extreme cases impossible; (c) that it is possible, though more laborious, to build up and state a comparative psychology without using terms de rived from the direct consciousness of mental process, merely by analysing modes of correlation; (d) that when we observe corre spondence, say between an animal's response to external things and our own, we must infer in the animal a function corresponding to that of which we are conscious though it may be that what per forms the function is not in all respects the same as in us. We are sure that our dog "recognizes" us, but it is equally apparent that he does so in terms of scent, a mode which to us is alien and almost incomprehensible. When describing animal behaviour in terms im plying conscious process we must always have this limitation in mind. On this condition we shall use such terms in the sequel.
The Structural Basis of Correlation.—All living things inherit a psycho-physical structure which lays the foundation of a self-sustaining and race-preserving life. One way in all organ isms in which the structure acts is by response to a stimulus, and some hold that all behaviour can in the last resort be reduced to responses to stimuli, external or internal. This theory is difficult to disprove because the internal stimuli are beyond the reach of exhaustive observation, but an hypothesis resting on vague possi bilities is of no value. There is no apparent reason why a struc ture should not be formed to act of itself in determinate ways, or why internal changes should not take place which at some point give rise to recognizable forms of behaviour. The real contrast, as experience shows us, lies between the specific response to specific stimulus and the subordination of passing or partial responses to a broad and relatively enduring line of behaviour.
Structures may be purely mechanical and give accurately pre dictable response to external influences. In the case of a man made machine, the external influence often resembles a stimulus in that it bears no quantitative or qualitative relation to its results, e.g. when a lightly-turned handle sets a powerful engine in motion. The condition is simply that all the mechanical con nections must be intact. But the working of the machine is in no way dependent on its successful execution of the result for which it was designed, and any part which is itself intact may work separately from the whole, as when a repairer having taken a machine to pieces works a part by hand and gets the responses normally given to the operation of the other parts. The parts then are in essentials indifferent to one another and work in the same way in or out of the machine. Some organic responses appear to be of this type. They seem to be governed neither by their results nor by the condition of the organism as a whole, but to depend purely on the integrity of communication be tween the part stimulated (the receptor) and the muscle, gland or other "effector." The contraction of the iris and the blink ing of the eyelids on the approach of a body to the face seem to be of this type. These are the true unconditioned re flexes. We get in these cases a vivid impression of a definite mechanism which, once set going, proceeds to its specific conclu sion without any of the variations in accordance with circum stances and consequences which suggest the operation of mind. More often however the reflex is not so completely unconditioned. Other parts of the organism may inhibit it. Other stimuli may modify it, and finally it may depend on what we can only call the general condition of the organism. Thus, sucking in young mam mals is a reflex response to a body placed within the lips, but the replete infant ceases to suck.
Acquired Response.—Reflexes play a large part in animal life from the protozoon which withdraws its pseudopodium on con tact with a blunt needle to a man who is set coughing by a crumb in the windpipe. Generally they are hereditary, and many are per fect from birth. while others, like the pecking of newly hatched chicks, need a little time to perfect them. With practice however a new element comes in, the continued influence of the results of action by which the hereditary reflex acquires perfection. But a good deal more may be acquired than this polish of a rough-hewn response. The newly hatched chick will peck at the edible and inedible indiscriminately at first, but very few experiments suffice to quell the response to inedible things like bits of orange peel and concentrate them on grains and the like. Here results oper ate at a slightly higher remove. At some point in or after the con tact with the peel the chick will try to reject the peel and there after avoids it. Our natural interpretation is that the taste is nasty, while that of the grain is acceptable. This raises the whole question discussed above of the interpretation of behaviour in terms derived from our consciousness. Following the principle there laid down, we shall say that something in the chick per forms just the same function as pleasant or unpleasant feeling in us. Whether, apart from this function, it is the same thing in a chick as in us we cannot say. If we use a term importing feeling, in this case "bad taste," of the chick, it is solely to express this identity of function.
But there is a further point. In ourselves we should say that we avoided certain food because we expected the bad taste. Probably this would not be true of the chick. It is more likely that the unpleasant reaction operates directly on the responding mechanism, and that the chick never has the act and its conse quence before it as two distinct objects. The result changes the whole character of the response, but by a process which we may call inarticulate as compared with that articulate forecast which we can make. All the lower grades of learning depend on these inarticulate correlations. In the case taken, experience of results inhibited response, but it may also engender positive responses, e.g., to "signals" where none previously existed. Pavlov, who has studied such responses elaborately under the title "Condi tioned Reflexes," makes the time factor a centre of importance, and this is probably true wherever the correlation is inarticu late. The signal must overlap the access to the food and must precede it. (Some qualifications of this general statement need not be considered here.) All sorts of arbitrary signals can be used and a dog will come to react to them by salivation in from three to 20 trials. Secondly, reflexes may be established by applying a new stimulus not less than io seconds before one to which response was already made, and in some cases even a third reflex was established in the same way. Beyond this it was not found possible to go. The acquired reflex, generally a measured salivation, could be easily distinguished by withholding the food, and, if a brief interval of time were allowed between signal and food, the appearance of the reflex would be proportionately de layed. It is evident that this behaviour closely resembles that which in man we call expectancy. How are we to decide by behaviour whether such an element is present or not? Conation.—The answer must be found in Conation, to which expectancy, so far as affecting action, belongs. Conation can be best understood in its developed form of deliberate purpose. In psychological terms purpose is that which directs action towards an end defined in an idea and guided by judgments of the relation of each act to the end. The objection made that the end is not always clear from the beginning, and is sometimes modified as we approach it, is not relevant. The facts on which it rests indi cate, sometimes that the purpose is not fully developed, some times that we only come to understand its conditions by trial and error, sometimes that it is inspired by some larger want which we have not ourselves understood. Purpose as such is that which directs action to ideal ends. The distinction between this and the reflex appears clearly in behaviour, for the reflex is the specific type response of a pre-formed structure, whether founded on heredity or acquirement. But in purpose we are free to vary our responses indefinitely as the bearing of the act upon the end may require. Outer objects become important which otherwise stimu late no response whatever. We make adjustments and combina tions that have never occurred before and may never occur again; we may vary our actions in the progress of the effort, discarding or correcting one that turns out useless and substituting methods which suit the case. All this, which can be easily amplified, but is of course familiar, may be summed up in the simple formula that in purpose behaviour is subject to continuous direction towards an end. Now this is the direct antithesis of the conception of mechanism, which is founded on the total exclusion of ends, and which would be revolutionized if we were to allow that the relation of a mechanistic change to some ultimate outcome were to be imported as a factor into our calculations.
But there are forms of conation which fall short of true pur pose. There are efforts towards an end of which there is no articulate idea. These are expressed in behaviour in more than one way. First, there is persistence in activity with variation of method until a certain result is attained; secondly, the result once attained, the method which has produced it is subsequently pre ferred, the others being discarded. This form of conation has been verified among protozoa by Jennings' well-known observations of "Stentor." It is the true foundation of the method of trial and error, where either we want something but do not quite know what it is, but only that we are dissatisfied with everything else, or we know what we want but do not know the means to it. This is the position of Professor Thorndike's cats, who want to get out of the cage in which they are shut, but not knowing how to do it, "scrabble" about till they at last happen to pull or push the catch which sets them free. The value of these experiments was to show the seemingly ingenious things which might be done by this method. There is thirdly the adjustment and combination of responses to the indefinitely varying requirements of a situation. Here any single response might be taken as mechanistically pre determined by heredity or habit, but the combination is a unique product that can never be repeated. There must then be a factor dealing with the situation of the moment as required by the bear ing on the result, otherwise the result is a success with no cause but "chance." The question may be asked, why we should deny ideas in such cases. The answer is that ideas are founded upon experience and in particular an articulate experience which in many of these cases is available. This brings us to the problem of instinct.
Thought is more than language but it is by expression and com munication that its achievements are consolidated and made the basis of further advance. Thus it is the social factor which makes its higher development possible.
BIBLIOGRAPHY.-C. Lloyd Morgan, Animal Behaviour; Emergent Bibliography.-C. Lloyd Morgan, Animal Behaviour; Emergent Evolution; I. P. Pavlov, Conditioned Reflexes, Eng. Trans., E. V. Anrep (5927) ; L. T. Hobhouse, Mind in Evolution (1925) ; J. Loeb, Comparative Physiology of the Brain and Comparative Psychology (1900) ; H. S. Jennings, Behaviour of the Lower Organisms (1906) ; E. L. Thorndike, Animal Intetligence (191I) ; W. Kohler, The Mentality of Apes (1927) ; Comparative Psychology Monographs, J. B. Watson, editor (1922—date) ; Journal of Comparative Psychology 092i—date). (L. T. Ho.)