28 



JOSEPH U. Y ARE ROUGH 



40 



Trials 



80 



120 



Figure 6 



180 



100 



80 



60 



40 



Trials 



80 



120 



180 



Figure 7 



Curves 8, 9, and 10 (Fig. 6) are the learning curves for Groups VIII, IX, 

 and X, respectively. Curves 10, n and 12 (Fig. 7) are the curves for 

 Groups, X, XI and XII. 



appears to be no increase in difficulty with an increase of the 

 time interval from two to four seconds. But when compared 

 with the data of Group V in which sound and pain were pre- 

 sented in the same temporal relation, two points of difference 



