Second, currently the WISC-R scale is used for classifying mental disability: 85-115 was normal; 50-70 was mildly retarded; 35-55 was moderately retarded; 20-40 was seriously retarded and below 20 was extremely seriously retarded. Another newer system doesn't divide people with Down's based on their I.Q., but instead divides them according to their environment and needs. Third, the retarded of all levels are said to have Down's Syndrome.
二、當前的智障分類在魏氏智力測量表驗（WISC-R Scale）裡，IQ 在八十五到一一五為正常；五十到七十為輕度智障；卅五到五十五為中度智障；廿到四十為重度智障，廿以下為極重度；另外最新的定義並不依智商高低來分，而是依環境和需要來劃分智障的程度。