THE QUESTION OF FORM PERCEPTION 



WALTER S. HUNTER, Ph.D. 

 The University of Texas 



Two figures 



The incentive for the writing of this note was furnished, by 

 the recent publication of two studies on form and size percep- 

 tion in animals. 1 The question T wish to raise is this: Is there 

 any evidence that animals discriminate form, as that term is 

 ordinarily used? Indeed I shall go farther and ask whether 

 it is fair to ask them to do so under the experimental condi- 

 tions described. 



An animal is trained to select a triangle in preference to a 

 circle of equal area. Adequate controls are used to insure that 

 the animal is not reacting to such extraneous cues as sound, 

 intensity, position, the experimenter, etc. Throughout these 

 series of controls the animal's reactions remain at a high per- 

 centage of correctness. Has it been established that a percep- 

 tion of form exists, or must one proceed to invert the triangle 

 as an additional control? Bingham says: 2 'Because his studies 

 of the reaction of other chicks to similar stimuli yielded nega- 

 tive results, Breed attributes the positive reactions of No. 76 

 to a fortunate choice of subject. Unfortunately, however, he 

 seems to have made no control tests to determine whether or 

 not the distribution of light on the chick's retina was influen- 

 tial. An inversion of a square would cause no change in the 

 distribution of light; such a change might have been produced 

 by turning the square through 45 degrees. A control test of 

 this sort, however, is more easily made when a triangle is pre- 

 sented along with a circle. Inversion of a triangle produces a 

 marked' difference in the distributions of the light which reaches 

 the retina, yet the form of the stimulus is unchanged." Bingham 



1 Lashley, K. S. Visual discrimination of size and form in the albino rat. Jour. 

 Animal Behavior, 1912, vol. 2, no. 5. 



Bingham, H. C. Size and form perception in Gallus domesticus. Jour. Animal 

 Behavior, 1913, vol. 3, no. 2. 



2 Op. cit., pp. 101-2. Italics mine. 



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