Dr. Clark administered a test, which he had devised years earlier, to 16 of those black children, who were ages 6 to 9. He showed them a black doll and a white doll and asked them what they thought of each. Eleven of them said that the black doll looked "bad," and nine of them thought that the white doll looked "nice." Seven of the 16 told Dr. Clark that they actually saw themselves as being closest to the white doll in appearance when asked, "Now show me the doll that's most like you."
"These children saw themselves as inferior, and they accepted the inferiority as part of reality," Dr. Clark said.
Clark's work is famously cited in footnote 11 of Brown v. Board of Education.