THE MAMMALIAN EYE 



S. B. VINCENT 

 From the Psychological Laboratory of the University of Chicago 



For the past ten years comparative psychology has busied 

 itself with animal experimentation and in such experimentation, 

 directly or indirectly, vision has played a leading role. Whether 

 the problem has been one of discrimination, imitation, or the 

 acquisition of some co-ordination like the maze, sight has been 

 always a factor, if not the important factor with which to reckon. 

 In spite of this, knowledge, structural or functional, of the 

 sense involved has been far from adequate if we may judge 

 from the way the work has been conducted and from the results 

 which" have been expected. 



It has been generally agreed that the vision of the white rat 

 is poor, yet in looking for anatomical, physiological or psycho- 

 logical data to support such contention or to show in what 

 respects it was poor, where it failed, no entirely satisfactory 

 answer was found anywhere. 



On the side of psychology, Mr. Small, speaking of some feats 

 of climbing before the eyes of the rats were open says, " Now 

 as the same movements are used in orientation after the eyes 

 are open as before one is led to conclude that the influence of 

 the eve in the orienting process is very slight." ' 



Mr. Watson thinks vision plays little part in the maze asso- 

 ciation. He says, " Many times we have taken our normal 

 rats and have flashed strong lights in their eyes. We never 

 got the slightest quiver of an eyelash by so doing much less 

 reaction of the animal as a whole." 2 



Mr. Yerkes concludes that sight is of little importance in 

 the life of the dancer, ''that movements and changes in bright - 



1 Small, W. S. Development of the White Rat. Amer. Jour, of Psych., 1899, 

 Vol. 11, p. 63. 



2 Watson, J. B. Kinaesthetic and organic sensations: their role in the reactions 

 of the white rat to the maze. Psychological Review, Mon. Sup., 1907, Vol. 8, No. 

 2, p. 90. 



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