VI. 



SUMMARY AND CONCLUSION 



1. The number of trials necessary to learn the association 

 does not increase proportionately with the increase of the time 

 interval between the presentation of sound and pain. 



2. Upon the basis of the number of trials necessary to make 

 the association, the difficulty of the problem steadily increases 

 with the increase of the time interval between the presentation of 

 sound and light, but this increase is not proportionate. 



3. Our data indicate no marked difference in difficulty for 

 the continuous and one-second interval presentations; likewise, 

 no marked difference is manifest for the intervals above two 

 seconds. The point of disproportionate increase is between one 

 and two seconds. 



4. The excess in the number of trials required for the animals 

 to transfer a motor response to sound over the number required 

 to transfer this response to light is perhaps due to the sense 

 material used, yet the transfer of training is an important factor 

 here. 



5. Association in the backward direction is very little, if any, 

 more difficult than in the forward direction when the continuous 

 mode of presentation is used. If, however, the two terms to be 

 associated are presented with a time interval of one second be- 

 tween them, the association in the reverse direction is perhaps 

 impossible. 



6. Under our experimental conditions and with the sensory 

 material used, our data indicate a slight superiority of the simul- 

 taneous mode of presentation. In order to show the relation of 

 our results to those of earlier investigators of simultaneous and 

 successive association, we may classify the findings of the latter 

 upon the basis of exposure time per term. Wohlgemuth (two 

 experiments), Bigham, and Chamberlain used an unequal ex- 

 posure time per term, the inequality favoring the simultaneous 

 mode, and in every instance they found the simultaneous mode 



