Mat 1, 1914] 



SCIENCE 



631 



tendencies in birds and mammals, and all 

 these in turn with the tendencies displayed 

 by human beings, either mature or im- 

 mature, either normal or abnormal. 



The two methods referred to are the 

 quadruple choice method of Hamilton'^ and 

 the multiple choice method of Yerkes. The 

 Hamilton method places the subject in an 

 experimental situation which may be re- 

 acted to in many different ways and with 

 varying degrees of satisfactoriness or ade- 

 quacy. The subject of the experiment is 

 placed in a small room on one side of which 

 there are four doors. From experience, he 

 learns that he may escape by one of the 

 doors, and only one, but which of the four 

 to choose is his problem, for it is the plan of 

 the experimenter to lock, in a given trial, 

 the door through which the animal escaped 

 in the previous trial and two others. Any 

 one, then, of three doors may be unlocked 

 in a given trial. The animal has absolutely 

 no way of predicting which is unlocked. 

 The general question is, then, how will a 

 given type of organism or a given individ- 

 ual meet this situation? What habitual 

 manner of meeting it will be acquired? 

 How will the modes of reaction displayed 

 by a child compare with those of an adult; 

 of an ape, with those of a man ? 



The Yerkes method is similar in purpose 

 to that of Hamilton, but it offers, in the 

 opinion of the writer, somew^hat more satis- 

 factory opportunity to evaluate and com- 

 pare results. It consists, essentially, in the 

 presentation to the subject — bird or mam- 

 mal ; young or old, normal or abnormal — of 

 a bank of twelve keys numbered from left 

 to right, one to twelve. The subject is 

 given to understand, verbally, or through 

 actual experience with the apparatus, that 

 pressing some one of the twelve keys will 



^ Hamilton, G. V., "A Study of Trial and Error 

 Reactions in Mammals," Journal of Animal Be- 

 haviw, 1911, Vol. 1, p. 33. 



yield a certain desired result, such, for 

 example, as the displaying of a picture, the 

 presentation of food, the ringing of a bell. 

 Success in the experiment means, simply, 

 pressing the key which brings the desired 

 result. The experimenter sees to it that in 

 no two successive trials is the same key the 

 one to be operated. He is, further, able to 

 push back out of sight any number of keys 

 and thus to present to the subject as few as 

 one or as many as twelve. 



Let us assume that in a given experiment 

 the observer decides that the key the fourth 

 from the left shall always be the "right" 

 one. It then becomes the task of the sub- 

 ject of the experiment to suit his reactions 

 to the number chosen by the experimenter. 

 Only if he discovers the guiding idea of the 

 experimenter can he succeed, trial after 

 trial, in touching the right key at first. 

 This method may be varied almost indef- 

 initely in difficultness, and it may be made 

 to elicit numerous reactive tendencies. 



It is obvioiis that both of the methods 

 thus briefly described above are attempts 

 to elicit general reactive tendencies rather 

 than to analyze reactions minutely and 

 carefully. The methods are indeed in- 

 tended to bring into clear light those modes 

 of responding to a given situation which 

 are characteristic of different types or con- 

 ditions of living beings, and thus to furnish 

 a basis for a profitable comparison of re- 

 active tendencies. 



I can not conclude this discussion with- 

 out referring for a moment to a question 

 which is frequently asked and which surely 

 must have been in the minds of some of my 

 hearers; namely, why is it that the behav- 

 iorist deals so often with the activities of 

 the lower animals and so seldom with those 

 of man ? The question is pertinent, and the 

 reasons, as I see them, are significant. 

 They are chiefly two: in the first place, 

 most lower animals are easily obtained, 



