But the Northwestern University study indicates despite the growth of the black middle class in the post-civil rights era, that is not necessarily the case for African-Americans.

"Because African-Americans continue to experience higher rates of discrimination, even when they do well economically, they are more likely than Latinos and Asian-Americans to identify with their racial group," said Dennis Chong, Northwestern professor of political science.

Chong and colleague Dukhong Kim based their study on data from a 2001 survey conducted by The Washington Post (NYSE:WPO), Kaiser Family Foundation and Harvard University. The survey over-sampled African-American, Latino and Asian-American respondents to permit a detailed comparison of the effects of economic status across groups.

"For individuals in all three groups, the effect of socioeconomic status depends on the experiences accompanying that status," Chong said, but noted he found black citizens are more likely to regard their interests in racial terms and to thereby evaluate public policies.

Chong and Kim presented the research in the journal American Political Science Review.