70 PSYCHOLOGICAL METHODS OP TESTING INTELLIGENCE 



gressively of less significance as a standard of varia- 

 tion : an intelligence that in the earlier years deviates 

 above or below the level of its age by even less than 

 a single year will in later years exceed this unit of 

 deviation, which has then become relatively smaller. 

 The same result had already been arrived at in in- 

 vestigating abnormal children, as will be shown in 

 the following section. 



4. Abnormal Children 



(a) Mental arrest and mental retardation. The 

 mental quotient. When Binet devised his system of 

 tests, he had particularly in mind the testing of ab- 

 normal children in order that children of this type 

 could be recognized opportunely and transferred to 

 the special classes and to the institutions for the 

 feeble-minded. Furthermore, Binet, together with 

 Simon, tried out his method upon a large number of 

 such children, though, unfortunately, he has given 

 us no detailed account of this investigation, but he 

 did draw conclusions from his experiments that 

 express the relation of feeble-mindedness to his 

 method in very simple formulas. One of these 

 theses refers to mental retardation and runs thus 

 (38, p. 113) : "I am for my part of the opinion that 

 every mental retardation amounting to two years 

 can be regarded as a serious deficiency. ' ' A second 

 of these theses refers to mental arrest and declares 

 that the imbecile does not progress beyond the 

 mental age of seven, the moron (feeble-minded in the 

 narrower sense) beyond the mental age of nine.* 



*By other investigators and elsewhere by Binet the upper limit 

 of moronity is placed at 12 years. Translator. 



