those iq tests are geared towards white folk and white folk norms, customs, view on reality/science etc. black people and minorities don't really care much for you so why would they do well on tests that are mainly asking qeuestions about you and what you believe to be true in this society. once again you corner there market of information, to suit your ideologies, which then again strengthen your position in society. If everybody is thinking like whitey, whats he got to worry about.