198 Journal of Comparative Neurology and Psychology. 



correlation between intelligence and another head measurement, 

 viz: horizontal circumference, with a value of .14 ± .04. While 

 some of the coefficients given by Pearson are, when taken by 

 themselves, insignificant in comparison with their probable errors, 

 we must give due weight to the fact that the sign of the correlation 

 when we deal with absolute head measurements and intelligence is 

 in all cases positive. 



In general I think the reasonable conclusion to draw is that from 

 the data now available it seems probable that there is a sensible, 

 but very slight, positive correlation between intelligence and size of 

 head. It will be understood that any conclusion regarding this 

 matter must for the present be more or less tentative. It is perfect- 

 ly clear that we are dealing here with a correlation of a very low 

 order, the general existence of which cannot be definitely asserted 

 till we have further statistics covering a wide range of social classes 

 of different races. How slight this correlation must in general 

 be is indicated by the fact which has been elsewhere brought out,^ 

 that what are probably the best series of brain-weight statistics 

 now available give no definite evidence of the existence of a posi- 

 tive correlation between that character and intelligence. The 

 results from the statistics analyzed in the present paper, though 

 the material was drawn from a very different population, essen- 

 tially confirm Pearson's conclusion that "there is no marked 

 correlation between intelligence and the size or shape of head." 



Suppose it be granted that it is a fact that there is, however, a 

 slight, though sensible, correlation between size of head and intelli- 

 gence, what interpretation are we to put upon the fact? It seems 

 to me that it would be absolutely fallacious to base upon these data 

 any general argument that "men of genius have large heads." I 

 quite agree with Professor Pearson in his conclusion that: "For 

 practical purposes it seems impossible, either in the case of excep- 

 tionally able men or in the bulk of the population, to pass any 

 judgment from size of head to ability or vice versa." If further 

 statistics (of which there is great need) should show that generally 

 there is a just sensible positive correlation between these charac- 

 ters, the correct interpretation of the fact would, it seems to me, 

 probably be physiologic rather than psychologic. That is to say, 



'Pearl, R. Biometrical Studies on Man. I. Variation and Correlation in Brain-Weight. Bio- 

 metrika. Vol. IV, pp. 13-104. 



