41 

 the most effective in the learning process, for it is 



apparent that less energy is consumed. Furthermore, 

 one trial given daily, though not so profitable in learn- 



as a trial given at greater intervals, remains more 

 economical and effective than when several trials are 

 given in succession. The further conclusion may be 

 reached that, if several problems are given concurrently, 

 fewer trials are necessary to learn them than if one pro- 

 blem had been learned completely before another had been 

 undertaken. But it has been shown, when comparing the 

 curves of several problems with those of one problem, that 

 the former are more irregular and learning is more difficult 



On the other hand, when several trials are given, 

 fewer days are required to learn a problem or problems. 

 The most economical in the number of days is when one 

 problem, with several daily trials, is given. Although 

 there is a saving in the number of days, learning is in- 

 creasingly difficult " : en several trials are given as 



