A DEFINITION OF FORM 139 



elements our animals do perceive. In this task we need not 

 speculate on the question whether such elements are logical or 

 genetic precedents of form perception. 



To avoid confusion, we should avoid the application of a 

 multiple meaning to the same terminology. We should not 

 attempt to simplify our definition of form so that this factor 

 may be included in the animal's stock of perceptual experiences. 



Finally, if we find that our animals have a power of discrimi- 

 nation which approaches form perception, but which is not 

 form perception in the strict sense of the term, we should adopt 

 a terminology to fit the special case; we should not enlarge the 

 conception of the term " form " to cover the special case. 



Perhaps " a more or less crude pattern vision " is the nearest 

 approach to form perception that animals possess. At any rate, 

 Hunter has done well in calling attention to the distinction 

 between patterns and forms. However, our definition must not 

 stop here. Two forms may be identical, but different in " shape." 

 This would be the condition in Lashley's study. He used two 

 identical forms in that both were rectangles 2 mm. by 60 mm. 

 They differ in this respect : one is extended laterally thirty times 

 as far as its vertical extension, while the other is extended ver- 

 tically thirty times longer than laterally. Now this is a difference 

 in " shape " of two identical forms. 



Miss Washburn, in reviewing my study, 7 has failed to make 

 this distinction between form and shape. She says : ' Bingham's 

 chicks discriminated between a circle and a triangle when the 

 apex of the triangle was on top, but since this discrimination 

 broke down when the circle was presented with a triangle whose 

 base was uppermost, the chick failing to choose the triangle, 

 Bingham concludes that the chick was not reacting to form 

 difference, but to ' the unequal stimulation of different parts 

 of the retina.' The reviewer would conclude rather that the 

 chicks were not possessed of an abstract idea of triangularity. 

 A triangle with apex up is a different form from a triangle with 

 apex down: the two have in common only the abstract quality 

 of three-sidedness. The perception of form, as distinct from an 

 abstract idea of form, is based precisely on the unequal stimu- 

 lation of different parts of the retina." 



7 Washburn, M. F. Recent Literature on the Behavior of Vertebrates. Psycho- 

 logical Bulletin, 1913, vol. 10, No. 8, p. 320. 



