22 K. S. LASHLEY 



dently different in reaction value from the yellow. The element 

 of intensity was not eliminated here but since the chicks had 

 been reacting so well to wave-length and not at all to brightness 

 differences I think it unlikely that the discrimination was made 

 here or in the following tests upon the basis of brightness. 



Chick E, trained like Chick A, was given 7 trials with 650 /*/*. 

 and 520 \x>\i, making no error. The red was then shifted toward 

 the shorter wave-lengths with the following results. 



Character of longer waves for 

 the human eye 

 Red. 



Red-orange. 

 Orange-yellow. 

 Yellow. Position habit. 

 Yellow-orange. Secondary evidence of 

 discrimination. 



This indicates that there is a change in the reaction value of 

 the spectrum between 580 and 590 mm. This is the region in 

 which the yellow assumes an orange quality for man. 



Chick D, positive to green, was first given 5 trials with the 

 red and green as in training, making no error. The test was 

 continued as follows: 



Wave-length, mm Chose 



Red "Green" Red "Green" 

 650 520 5 



650 600 5 Reactions prompt. 



650 630 Position habit developed at once. 



This indicates a change in the reaction value of the spectrum 

 between 600 and 630 ^. This is the region of the transition 

 from red to orange for man. 



Chick A was given the following tests. 



Wave-length, nu. Chose 



"Red" Green "Red" Green 



650 520 5 



610-590 520 5 



590-565 520 . 5 1 



(The reaction here with green and yellow was given upon the 

 basis of the green as negative color, the chick going to darkness 

 in preference to green.) 



550-530 520 2 2 Refused to advance. 



