314 WALTER S. HUNTER 



II 

 Learning Tuning Fork Chord — Tests were made upon 4 rats 

 in an attempt to set up an association between turning to the 

 right and a chord composed of the tones 512 d.v. and 640 d.v. 

 (both sounded on tuning forks) and between turning to the left 

 and the absence of the chord. Two of the rats (Nos. 37 and 

 38) were untrained. The other two (Nos. 31 and 32) had gone 

 through the tests with the fork 896 d.v. cited above. Table 

 2 summarizes the results. It will be seen from that that none 



TABLE 2 



Rats 



Trials 



31 32 37 38 



50 27 30 22 21 



100 27 29 26 26 



150 26 26 25 23 



200 26 26 23 29 



250 23 26 23 22 



300 22 25 29 25 



350 33 31 26 24 



400 28 30 21 26 



450 35 23 16 19 



500 38 31 26 26 



550 33 24 24 32 



600 31 24 26 27 



650 31 31 24 33 



of the rats learned the discrimination within the 650 trials 

 given. During this time there was a slight improvement in 

 the reactions of numbers 31 and 38; but not in the case of the 

 other rats. No. 31 ran as high as 76% and No. 38 as high as 

 66% during a period of 50 trials. Although these rats had 

 begun the tests with an accuracy of 54% and 60% respectively, 

 it was deemed advisable to put in controls and attempt to 

 determine the factors guiding the responses. 



Controls — The following controls were used: 1, chord not 

 sounded. Other conditions as usual. Reaction counted wrong 

 if it did not fit the series of presentations. 2, end-stops were 

 placed in each alley as opposed to one alley. The chord was 

 not sounded. Other conditions as in control 1. Using end- 

 stops in each alley served to equalize atmospheric conditions 

 in the two pathways. It appeared to the writer within the 

 realm of possibility that the rats might be able to detect a fresh- 

 ness of the air through the open pathway which would not be 

 present in the closed one. Their behavior was hesitant and 



