Reprinted from The Journal op Comparative Neui o 

 Vol. 54, No. 1. February, 1932 



STUDIES OF CEREBRAL FUNCTION IN LEARNING 



VIII. A REANALYSIS OF DATA ON MASS ACTION IN THE VISUAL CORTEX 



K. S. LASHLEY 

 Department of Psychology, The University of Chicago 



ONE FIGUEE 



In an earlier study of the effects of lesions v^ithin the 

 visual cortex upon the retention of a habit based on discrimi- 

 nation of light from darkness, I found evidence of a correla- 

 tion above p = 0.70 ±: 0.05 between the extent of cortical 

 destruction and the criteria of retention of the habit (Lash- 

 ley, '26). One of the possible causes of a spurious correlation 

 which I sought to control then was the<more frequent inva- 

 sion of a critical point by large than by small lesions. The 

 problem was stated as follows : 



Munk, Luciani and Seppilli, and other students of the visual area 

 have held that there is a focal point for visual function in the occipital 

 region, with surrounding areas of lesser importance, although still 

 concerned in vision. It is possible that in this series of operations 

 some lesions involved such a focal point, others missed it; that the 

 larger the lesion, the better the chance of including the focal point, 

 and that consequently a greater proportion of the larger lesions than 

 of the smaller produced loss of the habit and so led to a spurious 

 correlation. 



At that time there was no basis for a guess as to the posi- 

 tion of such a focal point, so the only possible control con- 

 sisted in showing that the areas common to all large lesions 

 which had resulted in marked loss of the habit might be de- 

 stroyed by small lesions with very little consequent disturb- 

 ance. More recent studies, involving the localization of pat- 

 tern vision (Lashley, '31), have shown that this function is 

 dependent upon a limited and definitely localized part of the 



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THE JOURNAL OF COMPARATIVE NBTJROLOGT, VOL. 54, NO. 1 



