Concerning intelligence and ethnicity, that IQ scores are low in places like Africa and high in Japan and the United States, does not mean the IQ scores are fundamentally wrong or one ethnic group is superior to another, because IQ scores are a measurement of an object called by psychometricians general intelligence, or g, which is considered to exist because of the positive correlation coefficients amongst various measures of g that psychometricians consider to be indirect evidence of an underlying faculty of humans, and from the usage of IQ tests and other intelligence measures with high correlation coefficients, comes–to pick this discovery to resolve the aforesaid issue–a conclusion that the more culturally neutral the items of an IQ test appear to be, the wider the gap in measured intelligence between two ethnic groups. To illustrate this through blacks (B) and whites (W),
The technical literature is again clear. In study after study of the leading tests, the hypothesis that the B/W difference is caused by questions with cultural content has been contradicted by the facts. Items that the average white test taker finds easy relative to other items, the average black test taker does too; the same is true for items that the average white and black find difficult. Inasmuch as whites and blacks have different overall scores on the average, it follows that a smaller proportion of blacks get right answers for either easy or hard items, but the order of difficulty is virtually the same in each racial group. For groups that have special language considerations–Latinos and American Indians, for example–some internal evidence of bias has been found, unless English is their native language.
so
The B/W difference is wider on items that appear to be culturally neutral than on items that appear to be culturally loaded.
–The Bell Curve by Richard J. Herrnstein and Charles Murray
