APPRECIATION OF INTELLIGENCE 31 



36-8 (boys) and 32-5 (girls) for the 1892 investigation; 

 among cases with all three defects the percentages are, as 

 we have just seen, 46-6 (boys), 41-2 (girls), and ^^-y (boys), 

 50-6 (girls). 



The same results appear when we deal with the effects 

 of binary defects of development, details of which are only 

 given for the 1888 part of the survey. Among children 

 with neither developmental nor nerve defects, the per- 

 centages of 'mentally dull ' were i-i for the boys and o-6 

 for the girls. Among those who had cranial defects only, 

 the percentages were 36-4 and 47-9 ; among children, how- 

 ever, who suffered from some other defect of development 

 in addition to defect of cranium, 46-5 % of the boys and 

 42-8 % of the girls are * mentally dull ' ! These results 

 might be multiplied indefinitely but what do they suggest ? 

 We saw that instead of an expected 50 % who are classed 

 as ' under the average in ability for school work', only 7-4 % 

 were so classed, while among the children for whom schedules 

 were filled up, 40-8 % are said to be 'under the average', 

 a reasonable approach to the theoretical 50 %. We saw 

 that among those ' scheduled ' children there was on the 

 whole no association between pairs of defects, and that in 

 some cases the association was a negative one. It has been 

 shown that the piling up of defects increased the percentage 

 of ' mentally dull ' in some cases, and in others decreased 

 this percentage. Finally, note the manner in which the 

 examination was practically confined to 18% of the 

 children while the other 82 % were summarily dismissed as 

 * normal '. 



All these point to only one conclusion — that the teachers 

 have given quite fairly their estimate of the intelligence of 

 the 18 % of children for whom schedules were filled up, but 

 have had no opportunity of doing so for the other 82 % who 



