Generally, there is considerable evidence of an 'ethnic' or 'racial' factor in stratification in Britain. Black people in general are treated less equally, and hold the lowest paid occupations, live in the worst housing, underachieve in the education system disproportionately and so on. Within this generalization, though, there are variations. Afro-Caribbeans are more consistently placed at lower levels than Asians, for example. Basically, black people were seen as members of a different biological group, a race.
Modern versions insist on genetic differences between black and white races.
Before we discuss it, you might like to consider the ethical and political issues of discussing work like this. Come and discuss your views with us, please, if they differ. The usual response to such findings is to argue that the IQ test is biased in some way in favour of white people, and that tests measure cultural differences. After several attempts to control for cultural factors, Eysenck concludes there must still be some residual factor to explain the differences between blacks and whites. Following a long tradition, he decides that this is a 'natural' or genetic difference.