THE EFFECT OF AGE ON HABIT FORMATION 

 IN THE ALBINO RAT 



INTRODUCTION 



The present investigation is concerned with the problem of 

 the relation of the age of an animal to its learning capacity. 

 Experiments were begun in the Psychological Laboratory of 

 The Johns Hopkins University during the winter of 1912, and 

 continued until the spring of 1915. 



HISTORICAL 



So far as the writer has been able to ascertain, practically 

 no prolonged experimental work has been undertaken hitherto 

 on the relation of age to learning ability, although the import- 

 ance of the problem has been generally conceded. 



In the field of human psychology, Munn^ carried out a series 

 of " substitution tests " on children in the grades, on normal 

 school pupils, and on two elderly persons, to determine the 

 relative rapidity of gain in ability to make the required sub- 

 stitutions. Her records were taken in the terms of time, and 

 showed that although the children gained much more rapidly 

 than the adults, their actual rate of speed at the beginning 

 was lower, and that they did not reach the same level of effi- 

 ciency w^ithin the limits of the experiment. Only two elderly 

 subjects were used, hence too much reliability cannot be at- 

 tributed to the results from the last group, but apparently, 

 while their initial rate is intermediate between that of the 

 children and the normal school pupils, they fail to reach the 

 final rate attained by either of them. Munn gives neither the 

 average nor the rate of gain for this last group, but the former 

 was easily obtained, and appears in the table below. 



Adults — first test 42 seconds — last test 14 seconds 



Children — first test 184 seconds — last test 32 seconds 

 Old persons — first test 72 seconds — last test 39 seconds 



^ Munn. Curve of Learning. Archives of Psychol., no. 12 p. 37. 



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