Reprinted from The Journaij of Comparative NEUEOiiOGT 

 Vol. 41, August, 1926 



STUDIES OF CEREBEAL FUNCTION IN LEARNING 



VII. THE EELATION BETWEEN CEREBRAL MASS, LEARNING, AND 



RETENTION 



K. S. LASHLEY • 

 • Department of Psychology of the University of Minnesota 



SEVEN TEXT FIGURES AND EIGHT PLATES 



CONTENTS , • ,>' 



Introduction 1 



Experimental methods 6 



Experimental data 13 



The effect of occipital lesions upon the initial formation of a visual habit. . 19 

 The effect of occipital lesions upon the retention of visual habits formed 



before operation 21 



The effect of thalamic lesions 33 



Interpretation of results 35 



Summary 46 



Literature cited 47 



INTEODUCTION 



Indications of a correlation between complexity of behavior 

 and the quantity of functional nervous tissue have been 

 given by various lines of evidence: comparative anatomy, 

 cerebral pathology, and physiological experiments have each 

 suggested such a relationship, but have provided no clue as to 

 the manner in which cerebral mass contributes to complexity 

 of function. The phylogenetic series offers the clearest 

 evidence for the importance of neural mass in determin- 

 ing intelligence, yet even this is not unequivocal. It is diffi- 

 cult to determine how much of the neural tissue is concerned 

 with purely vegetative or simple sensory-motor functions, 

 increasing in weight with the bulk of the muscles and the 

 surface area of the sense organs, and how much represents 



1 



THE JOURNAL OF COMPARATIVE NETTROLOOT, VOL. 41, NO. 1 

 AUGUST, 1926 



