Answer:
Cross-cultural research has found that members of stigmatized groups in many different societies tend to score 10 to 15 points lower on intelligence tests than members of dominant social groups, even if the stigmatized group members are of the same race as the dominant group.
Step-by-step explanation:
That phenomenon is most likely explained by a concept called stereotype threat, which is when people feel at risk of confirming negative stereotypes related to their racial, ethnic, gender, or cultural group. That means people belonging to a stigmatized group are led to believe they aren't as capable as people from the dominant group. They tend to perform more poorly than the dominant group when reminded that their own group has disadvantages.