A STUDY OF THE BEHAVIOR OF THE CROW 77 



experiments now to be reported were conducted for the special 

 purpose of obtaining definite and reliable information concerning 

 the nature and limitations of their ability to adjust themselves 

 to certain fairly simple, although novel, situations. 



We sought to make our measurements of intelligence by a 

 method recently devised at the Psychopathic Hospital, Boston, 

 by R. M. Yerkes, for the comparative study of ideational and 

 allied forms of behavior in man and other animals. This method 

 has been named the soluble-problem multiple-choice method. It 

 was devised primarily for the purpose of enabling the comparative 

 psychologist to present to any human or infra-human subject, 

 no matter what the age, degree of intelligence, or condition of 

 normality or abnormality, a series of situations increasing in 

 complexity from an extremely simple one to one so intricate 

 that even the most intelligent human subject might spend hours 

 or days in adjusting himself to it. By means of this multiple 

 choice method, it is hoped and confidently expected that the 

 materials of comparative psychology may be rapidly increased 

 and the analyses of animal behavior be made invaluable to the 

 psy chopathologist . 



A general description of the method should preface this account 

 of the special form in which it was applied to the crow, inasmuch 

 as only a very brief account of it has been published. 4 



In brief, the essentials of the method are these. A series of 

 reaction mechanisms, appropriate to the subject, are presented. 

 From this series one mechanism must be selected which, when 

 properly approached, will yield the subject the satisfaction of 

 success and, possibly, the reward of food. With each presenta- 

 tion of the reaction mechanisms, they are varied in number and 

 in position. The subject is therefore forced to select the proper 

 mechanism on the basis of some particular relationship of that 

 mechanism to its fellows, this relationship having been determined 

 upon in advance by the experimenter. It may be, for example, 

 such a simple relation as first at the left of the series as the 

 subject approaches, or first at the right of the series, or second 

 at the left, or alternately the first at the left and the first at 

 the right, or the middle of the series. Imagine, then a series 

 of piano keys which may be presented to a human subject. They 



4 Yerkes, Robert M. The study of human behavior. Science, 1914, 39, 625-633. 

 In this paper the writer describes his method in contrast with the Hamilton quad- 

 ruple choice method. 



