JOURNAL OF ANIMAL BEHAVIOR 



Vol. 3 JANUARY-FEBRUARY 1913. No. 1. 



A STUDY OF TLIE RESPONSES OF RODENTS TO 

 MONOCHROMATIC LIGHT 



JOHN B. WATSON AND MARY I. WATSON 



The Johns Hopkins University 



The following study on the responses of rodents to mono- 

 chromatic light was begun in January, 191 1 and was completed 

 in May, 191 2. Experiments were discontinued in the summer 

 of 191 1. From every standpoint the experiments are far from 

 being satisfactory. It is believed, however, it may be said at 

 the outset, that this paper offers some clear evidence that a 

 differential response on the basis of wave length is not possible 

 in the case of the rat. The tests (in Experiment II) upon the 

 rabbits were never completed. The results of what tests we 

 gave them are so similar to those obtained from the rats that 

 we believe that the total outcome of the work on the rabbits 

 would have been essentially the same as that reported for 

 the rats. 



The experiments were made with the color apparatus essen- 

 tially as it is described in Yerkes and Watson's monograph ' 

 and by the two color discrimination method there suggested. 

 The discrimination method is in such general use that no 

 description of it is necessary. 



EXPERIMENT I 



January 11, 1911-June 15, 191 1. 



The two stimulus lights were red (\=6$ 50) and green (A.= 

 5050). In this first experiment the two bands were not equated 

 in energy. They were projected directly upon the plaster sur- 

 face as they came from the selecting slit. Only two animals 

 were worked with—a pure white rat and a grey Belgian hare. 

 Both were about half grown at the beginning of the experi- 



1 Yerkes and Watson. The Behavior Monographs. 1911, vol. 1, no. 2. 



