spatially Determined Reactions 229 



tests with cards carrying various designs showed varying 

 degrees of capacity to distinguish them on the part of the 

 monkeys (708). Kinnaman got negative results with 

 his two Macacus monkeys in attempting to train them to 

 distinguish cards such as those used in the later experi- 

 ments of Porter on birds. His monkeys, however, proved 

 able to distinguish vessels of different forms, "a wide- 

 mouthed bottle, a small cylindrical glass, an elliptical tin 

 box, a triangular paper box, a rectangular paper box, and 

 a tall cylindrical can." These vessels differed in size as 

 well as in form (401). Johnson's far more accurate experi- 

 ments with the striped fields give the monkey a visual 

 acuity about equal to that of man. 



The question has been raised as to just what is meant 

 by the term "form" in connection with the visual percep- 

 tions of an animal. When Bingham (56, 57) found that 

 a chick failed to recognize a triangle whose base instead 

 of its apex was uppermost, he suggested that the chick's 

 previous discrimination of the triangle from a circle was 

 not a discrimination of form in the true sense of the word, 

 but based "on the unequal stimulation of different parts of 

 the retina." Hunter (352) thinks that the animal in such 

 a case is really discriminating pattern rather than form, and 

 by pattern he means the whole design presented by the 

 lighted forms and their surroundings. That is, a square 

 lighted area inside a round tunnel would present to the 

 animal a different pattern from a square lighted area 

 inside a square timnel ; an animal might fail to recognize 

 that the forms of the squares were identical when they 

 were presented as parts of such different patterns. The 

 writer of this book suggested in a review of Bingham's 

 work ^ that his chicks, in failing to recognize that a triangle 

 'Psych. Bull., vol. lo (1913), p. 320. 



