TRIAL AND ERROR REACTIONS IN MAMMALS 41 



degree of mental precocity, gave her a decided advantage over 

 all the other human subjects, including, even, the adult Man i. 



Boy 7. Age, 26 months. American of mixed descent (son 

 of the experimenter). At the time of the experiment he could 

 walk; had a limited vocabulary of words, which he did not put 

 into sentences; was able to find his way about the house; and 

 understood many simple commands. Very quick to form new 

 associations. 



Defective Man A. Age, 45 years. Native (Spanish-Indian) 

 Californian. Ranch laborer in the experimenter's employ. 

 Limited school education, but had read history and uncritical 

 w^orks on socialism. He was a nervous, suspicious, " muddled " 

 person, with a grievance against society in general, and a sur- 

 prising fund of self-acquired misinterpretations relating to his 

 social environment. He expressed a belief that my experiment 

 was dangerous meddling with the human mind, and that it had 

 some occult power of " making people crazy." His curiosity 

 and his desire to argue matters rendered him available, but he 

 seemed to be in constant dread of the apparatus, and always 

 labored under a suspicion that it was not the simple structure 

 that it pretended to be. 



Defective Boy A. Age, 11 years. English. With the excep- 

 tion of occasional perfunctory lessons from a governess, his 

 education was practically nil. He w^as barely able to read 

 simple words, was unable to respect the conventions of conversa- 

 tion usually recognized by a child of six years, and manifested 

 an inordinate fondness for asking questions. His cooperation 

 varied: at times he gave attention to the experiment, and did 

 well enough; and at times he behaved in a dull, mechanical 

 manner. His reactions are of considerable interest. 



* 



Monkeys 



Monkey 6.* Age, 15 years (estimated). Macacus cynomolgus. 

 About 10 years in captivity. Tame, and an excellent subject. 



Monkey 4. Age, 1.5 years (estimated). Macacus rhesus. 

 About 6 months in captivity. Very tame. After his 20th trial 

 his vision became defective, so that he had difficulty in finding 

 his way about the apparatus. His results do not appear in 

 any of the averages. 



* The writer has followed Professor Yerkes' (2) method of designating male sub- 

 jects by even numbers, and female subjects by odd numbers. 



