38 PSYCHOLOGICAL METHODS OP TESTING INTELLIGENCE 



According to it, one first ascertains up to what 

 age-level the tests are passed without failure (save 

 that possible failure with a single test is not counted, 

 because such failure may have been due to a momen- 

 tary lapse of attention). This age-level is taken as 

 the basis, but every five tests passed in levels above 

 it are counted as one more year. If, then, a child 

 should pass all tests (save a single one) to and in- 

 cluding the six-year level and in addition three tests 

 each in the 7th, the 8th, and the 9th year and one test 

 also in the 10th year, these ten additional tests would 

 be counted as two years, and the child would obtain 

 for the net value of his intelligence, 6 + 2 years, i. e., 

 his intelligence would be rated as that of an 8-year 

 old child. 



This net value in terms of which the total intelli- 

 gence of the subject is graded has, therefore, the sig- 

 nificance of an age-designation : it indicates that the 

 intelligence of the child tested is equivalent to the 

 average intelligence of the children of the age stated. 

 We thus arrive at the concept of mental age (Intel- 

 ligenzalter, niveau intellectuel) , which is the cardinal 

 feature of the method of graded tests. 



Now mental age must not, of course, be thought 

 of as an absolutely unequivocal determination of a 

 subject's intelligence, but only as a very rough quan- 

 titative characterization of its value, without any 

 implication as to qualitative differences, because one 

 and the same mental age can be figured from the 

 most varied sorts of distribution of passed and failed 

 tests. But this very thing appears to constitute an 

 advantage, rather than a disadvantage of the con- 

 cept of mental age, for it gives expression to a fun- 



