Final answer:
Kenneth Clark's research with dolls and racial identity used in the Brown v. Board of Education case illustrates the harmful effects of segregation and the unequal treatment of African American children.
Step-by-step explanation:
Social Psychologist Kenneth Clark's research with dolls and racial identity, which was used by the NAACP in the Brown v. Board of Education case, illustrates the harmful effects of segregation on African American children and the unequal treatment they experienced. The research involved asking children to choose between Black and White dolls, and the majority of Black children chose the White doll, indicating a lack of healthy self-concept. This research provided evidence that segregation generated feelings of inferiority in minority students, which contributed to the Supreme Court's decision to overturn the idea of 'separate but equal' and rule that separate educational facilities are inherently unequal.