TRIAL AND ERROR REACTIONS IN MAMMALS 



47 



puppies, their considerable number enables us to form two 

 age groups: the thirty-six-to-seventy-four days-old puppies and 

 the eighty -one-to-one hundred and sixteen-days-old puppies. 



TABLE 2 



No. of 



subjects in 

 Groups of subjects each group 



8-to-34-years-old normal human 8 



Defective man A 1 



Defective boy A. . . 1 



Infant Boy 1 1 



Mature monkeys 2 



Immature monkeys 2 



Defective Monkey 1 



Mature dogs 2 



81-to-116-days-old puppies 6 



36-to-74-days-old puppies 8 



Mature cats 3 



Kittens 2 



Horse 1 



Average age 



for entire 



group 



14 years 

 45 years 

 11 years 

 26 months 

 10 years 

 1 . 5 years 

 1 . 5 years 

 2 years 

 98.50 days 

 52.75 days 

 1 year 

 63 days 

 8 years 



Average 

 number of 

 efforts to 

 open exit 

 doors 

 201 . 75 

 217.00 

 237.00 

 315.00 

 276.50 

 275.00 

 291 . 00 

 313.00 

 333.00 

 377.75 

 352.00 

 387.00 

 461.00 



Ontogenetic aspects of table 2. The normal humans, the 

 dogs and the cats manifest a tendency toward increase in 

 number of efforts to open doors with decrease in age. This is 

 especially prominent in the case of the human infant, whose 

 record exceeds that of the average for the older normal human 

 subjects by 56.13 per cent. Defective Man A, whose record 

 appreciably exceeds that of the eight-to-thirty-four-years-old 

 normal human subjects, would doubtless have presented a 

 much higher record had he not manifested a marked tendency 

 to make first choice of the most remotely unlocked door during 

 each present trial. It may be said, indeed, that his total modes 

 of adjustment to the situations of the experiment were, on the 

 average, of a lower type than those manifested by defective 

 Boy A, whose record places him below Man A in the table 2 

 list. This additional evidence of the unreliability of the findings 

 of tables i and 2 as measures of intelligence will be brought 

 out more explicitly in sections IV and V. 



A general knowledge of the marked differences that obtain 

 between the behavior of an adult monkey and that of a half- 

 grown one would lead the student of behavior to expect that 

 under similar conditions no year-and-a-half old macacque would 

 find the unlocked door one hundred times with fewer efforts 



