"If you search FR there was a thread on a study of why West Indian and African blacks score higher on 'biased tests' and seem to fare 'better' than many black Americans."
I noticed the same degree of social separation between black Americans and those from Africa and the West Indies while I was at New Jersey Institute of Technoloogy (in the Central Ward of Newark) 1975-1979. The latter just could not make sense of the former "culture", and most did not buy into it. Most hung on to a lot of "British Empirisms."
Oh yes. There are lots of reasons why that is but it comes down to culture and differing experiences.