VISUAL PERCEPTION IN THE WHITE RAT

BY GLENN D. HIGGINSON

University of Illinois

Ingenious researches into the performance of vertebrates, especially of the anthropoid apes, have recently served to revive a flagging interest in the experimental study of the animals. Matters of great import to comparative psychology, long accepted without question, have been challenged in a noteworthy manner. The work of Koehler1 upon the higher apes is outstanding, not only in its scope but also in the character and the control of the experimental procedures followed. Koehler chiefly appealed, we may say, to the apprehensive functions of the animals under objective conditions which provided means of determining the ability of the ape so to extend a perceptual situation as to include a number of unrelated phenomenal items. The experimental setting approximated the customary environmental conditions, and the results consequently possess a peculiar scientific interest. In his interpretation of results, Koehler found much material exemplifying and substantiating, as he thought, the fundamental principles in the doctrine of configuration. It is not our purpose, however, either to discuss these investigations or their precise significance for the Gestalttheorie. We have referred to them because we find in the performances of the white rat something which we believe to be directly comparable to the activities of Koehler's apes.

According to the exponents of configuration, a perception is primarily characterized by its highly integrative and unitary aspects. A totality, not a sum of individual constituents, is the primary outcome of apprehension; the animal tending to perceive 'wholes' and not 'parts'; unified structures and not conglomerates. The 'parts' of these phenomenal unities 1 W. Koehler, The mentality of apes, 1925.

gather their particular significance from the total Struktur of which they are members, membership depending upon the degree to which they partake of the character of the whole or contribute to a particular functional outcome. That is to say, there is in perception a wide extension of functional performance whereby various objects are phenomenally integrated through a common purpose or goal or under a common need. In this apprehensive ligation the value of one object rests primarily upon its induction into a total situation. Thus a short stick utilized by the ape in securing a longer one by which food may be obtained is incorporated into the perceptual totality only when it bears upon it the functional mark of the total Struktur, namely, the obtaining of food. The stick comes to be manipulated under a wide extension of a formerly restricted meaning; for the stick is no longer, in any sense, a mere stick or object: it is a precise means of advancing an objective or of attaining an end. Moreover, to indicate the functional significance of a given 'member,' operative among others in furthering the organism, we may cite the fact that almost any object may, in the situation suggested, come to have the same functional value as the original stick. There results, then, a partial or total submersion in the total and unified whole of the individuality which previously characterized the object. It is no more just 'that thing' but has become even as Kinnaman put it years ago "a thing-which-hassomething-to-do-with-food-getting." The essential feature of this unifying process is that the apprehended relation of a particular member to the whole does not necessarily arise through a long sustained period of "trial and error." The induction may be quite sudden. In fact, we might say that the major contribution of these experiments consists in showing that, instead of an elaborate and sustained process leading to the final outcome, the 'solution' of a perceptual situation issues immediately. The goal, or end-result, even though fairly remote in time, functionates always as an integral part of a total Gestalt, determining the character of the animal's performance by bringing the members into a greater unity.

Without denying or affirming intelligence in the anthropoid

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apes-which is, after all, largely a matter of definition-we will doubtless agree that, in common with many other infrahuman and human organisms, the apes draw heavily upon visual perception as a major determinant of action. This fact must always be recognized when considering the matter of animal performance. Carr points out that the "process of perceiving is a constituent part of a larger act of adjustment and can be adequately comprehended only in terms of these wider relations." Most cases of intelligent behavior can be explained, no doubt, in terms of an intimate integration of the executive functions with visual apprehension under widely extended instruction of the 'occasional' kind. The remarkable performances of Clever Hans and of the Elberfeld horses, for example, have been shown to be cases of the close fusion of action with visual perception. Slight visual cues, usually imperceptible to the casual spectator, served to release and to check the course of action. What is true for these animals holds for others as well, including as we believe, the white rat. Our purpose here is to show that the visual capabilities of the rat are greater than men generally recognize; and that the rat utilizes visual resources in orientation more than we are commonly led to believe.

In approaching this matter of visual perception in the rat let us ask whether the behavior of the rat indicates, in common with Koehler's apes, an extension of visual apprehension such as to initiate a sudden shift in the actional performance which is incapable of explanation by the usual conception of 'trial and error' and by the 'laws' of frequency and recency. Can the rat visually perceive to advantage a sudden change in its path which offers a major reduction in its usual course toward food? Can it, e.g., in its quest for food see through a perceptual situation as the apes did? We believe that we have shown by experiments that rats do employ, in a novel manner, their apprehensive functions for adjustive purposes; that they are not, in any sense, automata, living machines controlled by kinæsthetic thrusts and precise neural patterns, as some have claimed, but instead organisms capable upon demand of sudden readjustments to significant environmental changes.

2 H. A. Carr, Psychology; a study of mental activity, 1925, 133.

To test the visual capabilities of the rat we made the following modification in a standard circular maze. At the entrance into alley 3 we placed a snugly-fitting door. During each of 100 runs the rat coming down alley 2 found a smooth wall to its right. If it ran to the end of the cul-de-sac, it found on its left, upon returning, the door open into alley 3; if, however, it failed to run the full distance to the end of the blind alley the door remained closed. The rat under no circumstance found the door open on its right. At the end of 100 trials, during which the animal each time went through the door into alley 3, turning always to the left (after running six feet out of its way), the animal was again introduced into the starting box and the alley 3 door, previously closed, was opened. Now one hundred runs necessarily meant a high degree of training for every animal, since the average rat learns the maze in something less than twenty-five trials. We expected that, with this amount of repetition, the animal would run, in spite of the open door, to the end of the alley and back again and so into alley 3 to the left. Curiously enough but four of the nine rats did and these four immediately shifted. The remainder exhibited the type of performance which most interested us. They stopped suddenly and without interference ran the remainder of the maze correctly, thus dropping at once six feet from the previous pathway and turning in a different manner. Apparently the sudden elimination of this extra six feet no more affected the total run than the addition, through error, of an occasional blind alley affects the remainder of the run of any rat acquainted with the maze. We know that even the best trained animal will upon occasion run into a blind alley or suddenly turn back upon its course only to finish perfectly the remainder of its run. Now this sudden elimination of six feet from the total pathway set up under continued repetition is wholly inexplicable in the usual categories of 'kinæsthetic patterns' and 'frequency and recency' of performance. Since the animals had never entered the door turning to the right, they could not have done so when the door was open, if we take frequency as the basis of performance; and if kinæsthesis ruled the animal the lifting

of the door should not have made any significant difference in performance; but since it did that fact must find explanation in visual terms. This employment of visual functions in the orientation of our subjects shows clearly that, for the particular demand made upon our animals, visual perception constitutes, under the conditions, an important functional resource of the organism.

It has long been widely asserted that in the acquisition of the maze visual factors are negligible in the rat; that kinæsthetic items constitute the vehicle by which the course of the animal is sustained; and that correctness of the course, including the elimination of errors, depends upon the frequency with which the true course is travelled in comparison with the number of times the animal enters a given blind alley. The rat thus becomes a mechanism wound up and needing only an introduction into the maze to release neural patterns which lead to a perfectly stereotyped performance. This way of regarding the rat may be traced particularly to the influence of Carr and Watson. The studies from which spread the impression that rats are machine-like do not appear, as we find, to warrant such an assumption; to claim otherwise is to disregard individual differences at the risk of obscuring the facts. With the general interpretation which has developed from these studies the writer has little sympathy. He is unable to agree, for example, that the white rat is incapable of sudden readjustments to a total situation through the novel use of the perceptive functions. His opinion, moreover, finds clear evidence of a confirmatory character in the literature. Since the contributions to this matter are extensive, we shall consider only the more outstanding.

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Small was the first to claim that the rat does not utilize visual functions in the maze; he based his conclusion upon the nature of the rat's response to visual 'cues' introduced at critical points in the maze. But we must question whether

'H. A. Carr & J. B. Watson, Orientation in the white rat, J. of Comp. Neur. & Psychol., 1908, 18, 30; J. B. Watson, Kinesthetic and organic sensations, Psychol. Rev., Monog. Supp., 1907, 8, 75.

4 W. S. Small, Psychic development of the young white rat, Amer. J. of Psychol., 1899, 2, 63.