It created a minor media frenzy last spring when President Barack Obama checked the "Black, African Am., or Negro" box on his census form and, as an item on The Root put it, "set the post-racial dream back 400 years." Elizabeth Chang, a mother of (Asian-Caucasian) biracial daughters and an editor at the Washington Post, excoriated him on that paper's op-ed page for failing to "celebrate" his biracial ancestry. And Michelle Hughes, president of the Chicago Biracial Family Network, voiced a complaint that many seemed to share when she observed that "the multiracial community feels a sense of disappointment that he refuses to identify with us."

A new study in the December 2010 issue of Social Psychology Quarterly, entitled "Passing as Black: Racial Identity Work Among Biracial Americans," is likely to rekindle the debate by providing evidence that black-white biracial adults are increasingly choosing, like Obama, to emphasize their blackness and downplay their white ancestry. In what the study calls "a striking reverse pattern of passing," a majority of respondents reported that they "pass" as black.

History, of course, is full of Anatole Broyard stories of mixed-race blacks who have personally profited by camouflaging their racial makeup and pretending to be white. What is novel today, according to the study, is that "multiracial individuals now feel more free to experiment with their identity and many express pride in their blackness and take steps to accent attributes that they consider black."

Expressing pride in their blackness -- that is a good thing, and the authors of the study use their data to make the case that this phenomenon of reverse passing demonstrates that blackness itself is less stigmatized today than in the past, which is certainly evidence of progress. However, what is troubling about the study is also what I find so disturbing about the criticism surrounding Obama's census decision -- namely, the flawed premise that in America, an opposition can exist between "biracial" and "black."