28 



K. S. LASHLEY AND L. E. WILEY 



which corresponds exactly to our average, but this can 

 scarcely be considered more than a chance correspondence. 

 If all conditions of random sampling are fulfilled, the coeffi- 

 cient of correlation gives a measure of the relative effective- 

 ness of a common factor and other causes of deviation in 

 determining the distribution of two series of variables. Our 

 data, however, do not fulfill the necessary conditions, and 

 the magnitude of the correlations only justifies the conclusion 



TABLE 13 



Correlations between total extent of lesion and the various criteria of maze 



learning for the five mazes studied 



TABLE 14 



Correlations between total extent of lesions and the various criteria of maze 

 learning for the comparison maze (maze V) 



that there is a significant relationship between the extent of 

 cerebral lesion and the amount of retardation in maze learn- 

 ing. 



In fact, the use of the correlation coefficient with our data 

 is justified only as a rough test of the existence of a relation- 

 ship. Data presented below show that the relationship is not 

 rectilinear and that the correlation ratio would more accu- 

 rately express it, as Lashley ('26) found for the effect of 

 lesions upon brightness discrimination. Since the distribu- 



