36 

 too 



80 



40 



JOSEPH U. Y ARE ROUGH 



Trials 



160 



JOO 



40 



Trials 80 



FIG. 9 



In Fig. 8 curves 2 and 3 are reproduced from Fig. 4; curve 13 is the 

 learning curve for Group XIII on sound, and curve I3L is for the same 

 group on light. Curve 14 represents the work of Group XIV. In Fig. 9 

 curve 15 is the composite curve for simultaneous groups (Groups I and 

 VII) ; curve 16 is the composite curve for successive groups (Groups II 

 and VIII). 



point, but the better controlled experiments report data indicat- 

 ing the superiority of the simultaneous mode. The difference in 

 materials used, experimental conditions, and methods of pro- 

 cedure, no doubt account for the conflicting results. Our data 

 support the superiority of simultaneous presentation. Almost 

 all results thus far reported have come from investigations with 

 human subjects, a fact which gives our data the more significance, 

 i ) Simultaneous Mode of Presentation. Two groups of ani- 

 mals learned to make the association when the two stimuli were 



