INTRODUCTION 



In 1907 we were asked by a Committee' on the standard- 

 ization of psychological methods, appointed by the American 

 Psychological Association, to attempt to devise " a standard 

 procedure for testing color vision in animals." This we under- 

 took to do. Four years have been devoted to the task, and 

 during that time the scope of the investigation has been extended 

 to include methods of stud3dng the perception of (a) light (color- 

 less), (b) size, (c) form, and (d) distance, as well as (e) color. 

 We thus broadened our task because knowledge of the light 

 vision of an animal is necessary for the intelligent study of its 

 color vision, and, further, because it seemed to us highly de- 

 sirable that closely related methods should be employed in 

 the quantitative investigation of the several aspects of vision 

 in an organism. 



We beg leave now to submit to the Committee a full report 

 of our researches. Although we feel encouraged by the progress 

 which we have made in our search for highly controllable methods 

 of studying the several aspects of vision, we realize that the 

 methods which we recommend as standard procedures should 

 be accepted rather as improvements upon procedures now in 

 common use than as new and perfect methods. Indeed, we 

 would urge the desirability and the fundamental importance 

 of continuous efforts to improve upon our present methods 



It is with pleasure that we express our indebtedness and 

 gratitude to the following individuals and scientific firms for 

 varied assistance. 



Especially in connection with the spectral color apparatus, 

 several physicists have aided us greatly. In fact, the construc- 

 tion of the apparatus would hardly have been possible without 

 the aid of Professors Millikan and Gale of the University of 

 Chicago and Professors R. W. Wood, A. H. Pfund, and J. A. Ander- 

 son of the Johns Hopkins University. For mechanical assist- 

 ance we thank Mr. C. M. Childs, mechanician attached to the 

 Physical and Psychological Laboratories of the Johns Hopkins 



'Consisting of Professors Angell, Judd, PillslHiry, Woodworth, and Seashore. 



