RESPONSES TO MONOCHROMATIC LIGHT 9 



intensity difference between the yellow and blue for the animals 

 was less than that between the 2 cp. light and 16 cp. light used 

 in the Hoge and Stocking work. This would account for the 

 failure of our animals to form the habit on the assumption of 

 brightness difference. 



Our reason for not prolonging the tests was that we wished 

 to try' the method of training the animals to respond to one 

 stimulus (the positive or food stimulus) and then gradually to 

 introduce the second (the light reacted against). Table III 

 shows the results. 



7 It will be remembered that all of these animals had previously worked with 

 one stimulus for about 200 trials (see table II). 



