A CAUSAL FACTOR IN THE RELATION OF THE 



DISTRIBUTION OF PRACTICE TO THE 



RATE OF LEARNING 



K. S. LASHLEY 



The Department of Psychology of the Johns Hopkins University 



The fact is well established that, within limits as yet unde- 

 termined, the rate of learning varies inversely as the concen- 

 tration of the periods of practice. A number of hypotheses 

 have been advanced to account for this but none of them has 

 any experimental evidence in its support. One of them, offered 

 by Book 1 to account for improvement in typewriting during 

 periods of non-practice, assumes that during a long period of 

 practice the learner may acquire certain habits which, persist- 

 ing through the practice-period, limit his chance activities and 

 hence his possibility of improvement by the method of trial 

 and error. During rest-periods these habits, which are not very 

 well established, may be lost, in which case a distributed prac- 

 tice would permit of a greater diversity of activity than a con- 

 centrated one. In other words, during a long period of prac- 

 tice the learner is apt to get into a rut and intervals of rest 

 permit him to return to the problem with a new " set " and to 

 attack it in a different way. 



The hypothesis applies not only to the periods of non-practice 



dealt with by Book, but to any of the effects of the distribution 



of practice. If it is correct, a detailed analysis of behavior in 



the formation of any habit should show a greater diversity of 



activity between successive practice-periods than within single 



periods. In my experiments upon the acquisition of skill in 



archery I observed the persistence of bad methods of aiming 



through single periods of practice but, lacking time for detailed 



descriptive or photographic records, was unable to determine the 



role of these in modifying the effects of practice. 2 



' x The Psychology of Skill: with special reference to its acquisition in typewrit- 

 ing. Missoula, University of Montana, 1908. 

 2 Acquisition of Skill in Archery. Carnegie Pub. 211. 1915. 



