MICHELE NORRIS, host:
There's an old expression: Seeing is to believing. Well, sometimes, what you believe can affect what you see. For example, skin color. According to a new study, you will see a biracial political candidate's skin as lighter or darker depending on whether or not you agree with his or her beliefs.
NPR's Nell Greenfieldboyce reports.
NELL GREENFIELDBOYCE: Eugene Caruso is a researcher at the University of Chicago. He recently asked: Do people's political beliefs affect how they perceive a candidate's skin tone?
Professor EUGENE CARUSO (Researcher, University of Chicago): And I guess, sort of being a social psychologist, I felt compelled to do at least one study with Barack Obama, given all the interest surrounding, you know, his campaign.
GREENFIELDBOYCE: He and two colleagues took existing photos of then-candidate Obama and digitally manipulated the parts of the photos that showed exposed skin.
Prof. CARUSO: So we sort of isolated the head and the hands of Obama and altered the skin tone to make it relatively lighter in tone, or relatively darker in tone.
GREENFIELDBOYCE: Then they showed the altered and unaltered photos one at a time to about 200 university students.
Prof. CARUSO: And essentially, we asked them to rate how well each of these photos represents who Obama really is.
GREENFIELDBOYCE: The students were also asked about their political beliefs and whether they saw themselves as liberals or conservatives. Here's what the researchers found.
Prof. CARUSO: Participants whose partisanship matched that of the candidate they were evaluating, so, say, liberals evaluating Barack Obama in this case consistently rated the lightened photographs as more representative of who he really was than the darkened photograph.
GREENFIELDBOYCE: People who disagreed with the candidate and held conservative views did the opposite.
Prof. CARUSO: That is, they rated the darkened photograph as more representative of who he really was, compared to the lightened photographs.
GREENFIELDBOYCE: Caruso says they didn't have a lot of non-white students judging the photos in this study, but their patterns tended to be the same.
Prof. CARUSO: And because we're basing our prediction on political party rather than racial identity, we sort of expect the results to hold somewhat independent of the participant's race.
GREENFIELDBOYCE: The results are reported in the proceedings of the National Academy of Sciences.
Keith Maddox is a psychology researcher at Tufts University who studied the social meaning of skin tone. He says the findings go with long-held cultural prejudices about things that are light as being positive and things that are dark as being negative.
Professor KEITH MADDOX (Psychology Researcher, Tufts University): You know, we think about, you know, the guy wearing the black hat as the bad guy, and the guy wearing the white hat is the good guy. You know, there are all these different sorts of cultural associations like, you know, angel food cake and devil food cake. And so, that's one of the reasons I find it interesting in that it's this idea that, you know, that political affiliation or that association that you might have with somebody who agrees with you can sort of change the way you perceive them in a real, kind of a real physical sense.
GREENFIELDBOYCE: He says people know their existing beliefs influence how they respond to someone's ideas. But they might be surprised to learn that their beliefs can literally shape the way they see the person.
Prof. MADDOX: If the brain can bias the perception of, you know, an opinion, it can bias the perception of somebody that we think of as more concrete like the, you know, the apparent physical appearance of somebody.
GREENFIELDBOYCE: He says it would be interesting to do a similar experiment with a biracial candidate who's conservative. He says this study suggests it would be the liberals who would darken that candidate.
Nell Greenfieldboyce, NPR News.