Stature Growth in Mental Deficiency.

Abstract

The concept of “ mental deficiency ” depends chiefly upon the grades of intelligence, so that their measurement by various intelligence tests isstill highly estimated even at present for the diagnosis of the deficiency. Recent studies on the frequency distribution of I. Q's in group intelligence tests as well as heredito-clinical investigations in this domain justify the proposal that mental deficiency cases should be classified into two types: the ordinary and the extraordinary.From this view-point, the stature growth in cases of mental deficiency, both endogenous and exogenous, was chosen as an indicator for the purpose of classification, and the investigation was held as to what sort of relations existed between this biological index and the intelligence.Cases of the juvenile delinquent, totaling 1010, were our material. As to the stature, each case was compared with the average stature of the Japanese boys or girls, and thus we have obtained the percentage, which was named as Stature Index. The following result was obtained by the statistical management between the above mentioned indices and the I. Q..1) Among the mentally deficients with pathologically retarded stature growth cS. I. below 93), there were many whose I. Q. was below 50, whileI. Q. amounted, in many cases, above 51 among those indicating almost normal stature growth (S. I. above 94).The author suggested to divide the mentally deficient intotwo groups, subnormal and pathological ones; the former reveals only the retardationto the degree of the subnormal intelligence, while on the other hand the latter indicatesrelatively low I. Q. which is rather regarded as a partial phenomenon of general growth disturbances. The investigations thus performed using stature as an index, seems to favor the above-mentioned stand-point.2) The overlapping of these subnormal and pathological groups was found to fall in the range between 50 and 80 of I. Q..