36 G. V. HAMILTON 



this would be expected to manifest less than 25% of recency- 

 first choices. Table 8 shows that only 1 of the 49 subjects 

 (four-year old Girl 4) had more than 25% of recency first choices 

 if we exclude the cases where first choices sustained the relations 

 of both recency and frequency to previous trials. If we do not 

 exclude such cases, 17 subjects — 2 girls, 1 baboon, 1 monkey, 

 2 gray rats, 2 black rats, 6 white rats and 3 gophers — had each 

 more than 25% of recency first choices. 



Frequency was apparently an important determinant of first 

 choices. In making the calculations for table 8 a frequency 

 reaction was recorded whenever the subject made first choice 

 of the alley that had been most frequently entered during all 

 preceding trials. The table shows that 27 subjects — 11 girls, 

 1 baboon, 3 monkeys, 1 mouse, 4 gray rats, 3 black rats, 2 white 

 rats and 2 gophers — had each more than 25% of frequency first 

 choices if we exclude the cases where first choices sustained the 

 relation of recency as well as of frequency to previous trials. 

 If we do not exclude such cases, 40 of the subjects had each more 

 than 25% of frequency first choices. 



The averages for the primate and rodent groups given in 

 table 9 are of some interest. Subjects which had less than 100 

 trials each are excluded from this table: 



TABLE 9 

 Averages of Recency, Frequency and Recency-Frequency First Choices 



Group Recency Frequency Recency-Frequency 



Primates (22) 11.55% 30.68% 9.09% 



Rodents(23) 15.96% 28.91% 9.87% 



« 



This table suggests various interesting problems. It would 

 be of considerable importance to have sufficient experimental 

 data on which to base a conclusion as to whether with descent 

 in the phyletic scale the relative importance of recency and 

 frequency changes in favor of recency. Table 9 suggests that 

 with ascent of the phyletic scale the role of recency as a deter- 

 minant of habit formation decreases whilst that of frequency 

 increases, but the individual variations from the averages are 

 too marked to render this a legitimate interpretation. 



The fact that the rodents, as a group, were not more influ- 

 enced by the factor of recency under conditions which rendered 

 the operation of this factor disadvantageous did not attract my 



