Gbe Tflntt>er6it of Chicago 



The Influence of the Time Interval 



Upon the Rate of Learning 



in the White Rat 



A DISSERTATION 



SUBMITTED 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. 



