158 



Animal Intelligence 



far is the evidence that from the first the chick reacts to all 

 colors. In no case was there any random pecking at the 

 white surface of the cardboard. 



On a black background the same chicks reacted to all the 

 colors. 



II is a table of the results. 



II 



In other experiments chicks were tried with green spots on 

 a red ground, red spots on a green ground, yellow spots on an 

 orange ground, green spots on a blue ground, and black spots 

 on a white ground. All were reacted to. Thus, what is ap- 

 parently a long and arduous task to the child is heredity's 

 gift to the chick. It is conceivable, though to me incred- 

 ible, that what the chick reacts to is not the color, but the 

 very minute elevation of the spot. My spots were made so 

 that they were only the thickness of thin paper above paste- 

 board. Any one who cares to resort to the theory that this 

 elevation caused the reaction can settle the case by using 

 color-spots absolutely level with the surface. 1 



1 The crude experiments reported in this and the preceding paragraphs 

 were not made to test the presence of color vision proper, that is, of differ- 

 entiation of two colors of the same brightness, but only to ascertain how 

 chicks reacted to ordinary colored objects. It was, however, almost certain 

 from the relative frequency of the reactions that the intensity factor was not 

 the cause of the response. For example, if it had been, black on white and 

 yellow on black should have been pecked at oftener. 



