TRIAL AND ERROR REACTIONS IN MAMMALS 61 



nificance of this behavior. One looks into every likely nook 

 and corner, then remembers that on previous occasions he has 

 discovered lost articles in a drawer which is seldom used because 

 of its tendency to " stick." The drawer is opened and is found 

 to be quite empty; one turns away and looks elsewhere, only to 

 return in a moment to the empty drawer and again to open it 

 in a stupid, unthinking manner. The impulse to open the drawer 

 seems to have subsided with the first failure, only to come surg- 

 ing back with most inappropriate persistence. 



Type D reactions will hereafter be referred to as due to " the 

 searching tendency modified by recrudescent motor impulses." 



Type E. This type includes several different modes of behav- 

 ior which have a common objective characteristic, viz., auto- 

 matism. That is, the subject behaves in a relatively implastic, 

 unadaptive manner. The objective characteristics of the various 

 sub-types may be reviewed as follows: 



Sub-type a. The subject makes two or more successive but 

 definitely separate attempts to open the same door during a 

 given trial. Thus he tries Door 3, finds it locked, turns away 

 from it, returns to this same door and makes a second effort 

 to open it without having tried any other door in the meantime, 

 etc. In view of the fact that in the majority of cases such per- 

 sistence in returning to the same door during a given trial could 

 not be attributed to the recency with which it had afforded 

 escape (as compared with the recency with which the other 

 doors had afforded escape), we are justified in assuming, I 

 believe, that the sub-type a reaction is an expression of the 

 unmodified primitive tendency to repeat an activity, once it 

 is begun, until it leads quite definitely to pain or success. 



Sub-type b. During a given trial the subject tries a group 

 of locked doors two or more times in an unvarying order. Cat 

 I's ninety-fifth trial well illustrates this mode of adjustment. 

 When this animal entered the apparatus to meet, for the ninety- 

 fifth time, a situation which merely required that she find the 

 one unlocked door, she tried the exit doors in the following 

 order: 2-1-4 " 2-1-4 ~ 2-1-4 ~ 2-1-3- ^ have italicised each of 

 three exactly similar cycles of activity in order to bring out 

 more clearly the characteristic features of a mode of adjustment 

 which seemed to spring from a persistent impulse to try Doors 

 2, I and 4 again and again, in an unvarying order. Now during 



