74 PSYCHOLOGICAL METHODS OF TESTING INTELLIGENCE 



of a given mental age. But all of these statements 

 stand very much in need of further testing. 



It is well to give here explicit warning against a 

 certain false conception of the term "arrest." An 

 imbecile who, during his life, never progresses past 

 the mental age of seven, is not on that account to be 

 thought of as the same as a seven-year old child. 

 He does grow beyond that status in many respects : 

 he acquires experiences that a normal 7-year old 

 child does not possess, picks up many accomplish- 

 ments, experiences the awakening within himself of 

 impulses and needs that come with increasing years. 

 The arrest, then, pertains only to that specific group 

 of mental abilities that are tested by the tests. And 

 even some ones of these abilities may show some de- 

 velopment (cf. in this connection p. 86), only there 

 still remain so many defects of a fundamental na- 

 ture that, all in all, it is impossible for him to rise 

 above the mental age of seven. 



Of importance is, furthermore, the discovery that 

 Goddard made concerning the mental age of a spe- 

 cial group, the morally feeble-minded. It turned out 

 that this group was recruited solely from the upper 

 of the age-levels represented in the institution. Of 

 22 such individuals, 15 had the mental age 9, 5 the 

 age 10 and one each the ages 11 and 12. The circum- 

 stance that moral defects do not extend down be- 

 yond the mental age nine is explained by Goddard 

 in the following way: Certain immoral instincts, 

 like the impulse to lie, to steal, etc., normally awaken 

 about the ninth year; later on reasoning develops 

 and puts these tendencies under inhibition. With 

 children whose mental age is below nine those in- 



