14 



K. S. LASHLEY 



TABLE 3 

 Summary of First Tests for Red-Green Discrimination 



The tests in which white light was substituted for each of 

 the lights in turn are interesting as indicating the relative im- 

 portance of the negative and positive stimuli in determining 

 the reaction. Both chicks confused the white with the positive 

 stimulus (table 3) and distinguished it readily from the negative. 

 Punishment had been used in this case with the negative light 

 which here appears to be most clearly recognized. In later 

 experiments without punishment conditions appear to be re- 

 versed, the negative light being most frequently confused with 

 the white. This is in accord with the view that punishment 

 is the more efficient factor in learning. The tests also evidence 

 either color discrimination or accurate perception of brightness. 

 The use of the lights singly gives further evidence of the same 

 sort, since darkness was chosen fewer times with the positive 

 color than with the negative (table 3). 



The work had to be dropped at this point. The tests recorded 

 make it highly probable that the birds were reacting upon the 

 basis of wave-length, but as the energies of both red and green 

 were never altered simultaneously, the possibility that an ex- 

 tremely accurate perception of absolute brightness furnished the 

 basis for reaction was not completely eliminated. It seemed 



