346 ENVIEONMENT AMONG MEN 



7. Attempts have been made to obtain more precise information 

 by the use of statistical methods. Thus the correlations have been 

 measured between the state of children's eyesight and fifteen 

 environmental conditions. The mean of the correlations was 

 found to be 0-04 — only one reaching 0-1. ^ Again the association 

 between various intellectual and physical characters and con- 

 ditions, which were taken as representing a good or bad environ- 

 ment, has been measured. A slight association was found between 

 intelligence in boys and few people per room and no association 

 between eyesight, condition of glands and hearing, and bad 

 economic and moral surroundings .^ Somewhat different results 

 have been reached by American workers, who find that by 

 employing psychological tests a fairly well-marked difference 

 can be detected between children in the same school whose 

 parents belong to different social classes and who would therefore 

 be subject to different home conditions.^ 



The interpretation of these results is difficult. Before any 

 definite conclusion could be reached with regard to any one 

 character, it would be necessary to measure the effect of every 

 factor in the environment upon that character. As the matter 

 stands there is strong but not conclusive evidence of the small 

 influence of the surroundings, so long as we suppose that innate 

 differences do not exist between the subjects measured. But if 

 innate differences exist, then the interpretation of the absence 

 of any marked degree of correlation must be that the common 

 elements of the environment supplied by the community are of 

 greater importance than the innate differences. We shall find 

 reason to conclude in later chapters that small innate differences 

 do exist, and, if this is so, then the interpretation of these results 

 is not at variance with the general, though necessarily vague, 

 conclusions derived from the evidence previously given, i.e. that 

 the influence of the environment as represented by the variations 

 actually occurring in the elements of the surroundings hitherto 

 mentioned is small. 



8. There is another class of factors which may be summed up 

 under the heading of disease. It was remarked that disease 

 may produce notable results among species in a state of nature. 



1 Barrington and Pearson, Eiig. Lab, Mem., No. 5, 1909. ^ The results of 



these investigations have been summed up by Miss Elderton in a pamplilet entitled 

 The Relative Strength of Nature and Nurture. ' See, for instance, Bridges and 



Coles, ' Relation of Intelligence to Social Status ', Psychological Review, vol. xxiv. 



