UC-NRI 



B 3 BDD flEl ^m 



Tflntversiti? of Chicago 



The Influence of the Time Interval 



upon the Rate of Learning 



in .the White Rat 



A DISSERTATION 



SU! fITTED TO THE FACULTY 

 OF THE 



GRADUATE SCHOOL OF ARTS AND LITERATURE 



IN CANDIDACY FOR THE 



DEGREE OF DOCTOR OF PHILOSOPHY 



(DEPARTMENT OF PSYCHOLOGY) 



BY 



JOSEPH USSERY YARBROUGH, PH.D. 



A Private Edition Distributed by 

 The University of Chicago Libraries 



A Trade Edition is Published as No. 135 of the Psychological Mono- 

 graphs by Psychological Review Co., Princeton, N. J. 



