PERSEVERANCE REACTIONS IN PRIMATES AND RODENTS 21 



perimental situations are unfamiliar and complex. If, e.g., a 

 difficult maze or puzzle box situation be presented to a half 

 dozen mammalians of the same age and species their first-trial 

 random movements will be found to vary markedly from indi- 

 vidual to individual. Unfortunately, only such differences as 

 can be tabulated in terms of reaction-time and numbers of errors 

 are apt to be recorded in experimental studies of habit forma- 

 tion. One of the most important generalizations, perhaps, that 

 can be based upon Table 2 is this: 



When a mammalian is confronted by a series of situations for 

 which he is unable to discover and stereotype a specifically adequate 

 and invariably successful mode of response he tends to vary his 

 responses in a manner which is less a species than an individual 

 characteristic. 



Mammalian neural organization is so complex and its func- 

 tions are so plastic that there is excellent ground to assume, 

 a priori, that slight individual differences of reactive equipment 

 will be reflected by marked differences, as to detail, of behavior 

 which conforms to the random movement type. Further ex- 

 emplification of this point can be found in comparisons of the 

 specimen individual records given in the appendix. 



Although a Type A reaction presents the objective character- 

 istics of a response which has reference to an inferred principle 

 or experiment rule, its occurrence can be regarded as such with 

 certainty only when, in the course of a large number of trials, 

 it clearly predominates over all other types It was the most 

 frequently manifested reaction of three-year old Girl 1, five-year 

 old Girl 8, seven-year old Girl 11, nine-year old Girl 16, nine- 

 year old Girl 19 and feeble-minded, twelve-year old Girl 20. 

 No animal subject presented an excess of Type A reactions over 

 any other type of reaction during the first series of 100 trials. 

 Baboon 2 had an equal number of Type A and Type B reac- 

 tions during his first 100 trials, and during his second and fifth 

 series he had a plurality of Type A reactions. These reactions are 

 wholly absent from the records of but two subjects, viz., four- 

 year old Girl 4 and feeble-minded, six-year old Girl 10. These 

 two girls stereotyped a method of response which, as can be 

 seen from a glance at their records in the appendix, precluded 

 the possibility of " by-product " or accidental Type A reactions. 



