18 HAROLD C. BINGHAM 



ular feature about this general distribution of light — it is equi- 

 lateral, or isosceles, or right angled — which is called shape. 

 Forms are identical when their areas are equal and their general 

 retinal distribution is similar. Shapes of forms are identical 

 when all extension of the identical forms are equal and in cor- 

 responding directions. Thus, the area remaining constant, 

 either or both form and shape may change. The form remain- 

 ing constant, the shape may change. Change in form must 

 always be accompanied by change in shape. 



Unquestionably the test of form perception by inversion of 

 the triangle is a severe one. But if this test of inversion is 

 found to interrupt the discrimination, form perception in the 

 strict sense of the term can scarcely be said to prevail. More- 

 over, there is evidence that form perception regarded not as an 

 abstract idea but as perceptual phenomena does not exist. 



More in line with Washburn's inclination to regard my inter- 

 pretation of form as "an abstract idea of triangularity" (32) is 

 my incidental observation (2) of reactions to relative stimulus 

 difference. Because a few chicks showed ability to carry the 

 correct large-small reactions from a 6-4 training to a 4-3 or 

 9-6 test situation, it would seem that the chick has some sort 

 of ideational content. Watson, having been informed by John- 

 son that the latter failed to secure positive evidence in this 

 relative stimulus problem with a single adult game bantam, 

 hastily remarks (33): "From experiments now in progress at 

 Nela Physical Laboratory (Johnson) it would seem that this 

 observation cannot be confirmed." Johnson, however, is more 

 conservative and disclaims Watson's unguarded remark by sug- 

 gesting that the variation is due to individual differences partic- 

 ularly because it was found that not all of my subjects reacted 

 positively to this problem. Moreover, I found only one chick 

 that reacted positively and perfectly to both of the unfamiliar 

 combinations. Doubtless, the amount of training has much to 

 do with the nature of the reaction. 



One of the best controlled studies employing the dark room- 

 discrimination method is reported by Johnson (15-16). His 

 report, appearing as two papers, is on the detail vision of the 

 dog, the monkey, and the chick. The first paper deals with 

 standardization of method in which he presents certain improve- 

 ments upon the Yerkes-Watson apparatus. He commendably 



