A provocative new study (.pdf) forthcoming in the Proceedings of the National Academy of Sciences seems to show that people perceive a bi-racial candidate to have lighter skin color when they agree with him. That is, voters who like Obama tended to pick the photo on the left, above, as most representative of him.
People tend to view members of their own political group more positively than members of a competing political group. In this article, we demonstrate that political partisanship influences people’s visual representations of a biracial political candidate’s skin tone. In three studies, participants rated the representativeness of photographs of a hypothetical (Study 1) or real (Barack Obama; Studies 2 and 3) biracial political candidate. Unbeknownst to participants, some of the photographs had been altered to make the candidate’s skin tone either lighter or darker than it was in the original photograph. Participants whose partisanship matched that of the candidate they were evaluating consistently rated the lightened photographs as more representative of the candidate than the darkened photographs, whereas participants whose partisanship did not match that of the candidate showed the opposite pattern. For evaluations of Barack Obama, the extent to which people rated lightened photographs as representative of him was positively correlated with their stated voting intentions and reported voting behavior in the 2008 Presidential election. This effect persisted when controlling for political ideology and racial attitudes.
The study seems to indicate in passing that the race of the participants doesn’t effect the outcome, though it isn’t totally clear on that point. It also seems to buy into the claim that Hillary Clinton artificially darkened an image of Obama, which wasn’t terribly widely believed.