44 G. V. HAMILTON 



Type A. — Response to confinement by trying three trial-to- 

 trial varying inferentially possible exit alleys, the one trial-to- 

 trial varying inferentially impossible exit alley not being tried 

 by the subject. 



Type B. — Response by trying all four exit alleys, but once 

 each and in an irregular order. 



Type C. — Response by trying all four alleys but once each and 

 in regular order from left to right or from right to left. 



Type D. — Response by entering a given alley more than once 

 during a given trial, with an interval of effort to escape by 

 another alley between entrance and reentrance of the same 

 alley. 



Type E. — (a) Response includes two or more separate efforts 

 to escape by the same alley or group of alleys during a given 

 trial without intervals of effort to escape by other alleys, 

 (b) Response includes persistent avoidance of a given alley dur- 

 ing a given trial whilst six or more separate efforts to escape 

 by the other alleys are manifested. 



3. None of the subjects of these studies manifested a con- 

 sistent appreciation of the inferentially impossible, trial- to-trial 

 varying one impossible exit alley as the one alley that would 

 not afford escape from confinement, hence Type A reactions 

 were not exclusively manifested by any subject. The use of 

 an inferior class of human subjects must be held to account for 

 the fact that the maximum number of Type A reactions was 

 manifested by a three-year old and a five-year old girl in a 

 group of 20 children whose ages ranged from three to twelve 

 years. Nevertheless, the children manifested a higher average 

 number of these reactions than did any of the animal groups. 

 The infra-human primates average of A-reactions was higher 

 than that of any of the rodent groups. 



4. If we exclude the case of the single mouse that was used 

 in these studies, B -reactions were of more frequent occurrence 

 among infra-human primates than among any of the other 

 groups. The only human subject who manifested a consider- 

 able number of B -reactions was feeble-minded twelve-year old 

 Girl 20. 



5. The girls manifested the highest average number of C- 

 reactions. Their average in this respect is slightly lowered if 



