A REVIEW OF YERKES' AND WATSON'S "METHODS 

 OF STUDYING VISION IN ANIMALS" 1 



By S. O. MAST 



Nothing in the whole realm of literature on the behavior of 

 animals shows as clearly as this monograph that we have out- 

 grown the purely qualitative stage in this branch of science 

 and have actually entered upon the quantitative phase. The 

 monograph is indeed devoted almost entirely to methods de- 

 signed for the prosecution and encouragement of work in this 

 more advanced stage of the subject. The authors say on page 

 3: "Our standard procedures are recommended only for thor- 

 oughgoing, intensive, quantitative work. Simpler and more 

 conveniently manipulated apparatus may be used in the case 

 of preliminary exploratory work. We do not wish to discourage 

 the use of crude and relatively uncontrollable methods for the 

 study of vision, but 'we do most emphatically recommend that 

 these methods be abandoned as soon as the rough problem- 

 defining portion of an investigation has been completed." 



These sentences state in admirable form the guiding princi- 

 ples of the whole investigation on methods. The authors appar- 

 ently spared neither time nor labor in perfecting apparatus by 

 means of which the ideal set forth in the quotation above could 

 be attained. As a result we have an excellent description of 

 the construction and working of a "Light or Brightness Appa- 

 ratus" and a "Spectral Color Apparatus." Neither of these 

 pieces of apparatus bears the slightest apparent relationship to 

 the home-made variety with which most of us are familiar. 

 They are in reality instruments of precision of the highest order, 

 comparable in accuracy of construction and adjustment with a 

 high grade microscope. 



The light apparatus is adapted for the investigation of prob- 

 lems associated with brightness, size or form. By means of it 

 animals can be simultaneously subjected to light from two 

 sources, (1) of the same size and form but differing in intensity, 

 (2) of the same intensity and size but differing in form, and 



'Behavior Monographs, vol. 1, no. 2. Pp. IV + 90. 



147 



