Innate biases against diversity. There exists in many people a desire to preserve various uniformities. Many individuals, perhaps most individuals, prefer individuals who are like themselves: who look like themselves, act like themselves, talk like themselves, and think like themselves.
A curious experiment by Jeremy Bailenson provides further evidence that this is so. The experiment, as described by Desteno and Valdesolo, went as follows:
In the weeks leading ... to the 2006 election, the researchers selected a randon sample of people all over the country to participate in a computer-based study. First, they were asked to upload a recent photograph of themselves.... Then, the week of the election, they were shown a picture of each candidate and asked to complete a questionaire asking them to indicate how they felt about the candidate on a host of measures. Now, they weren't given any other information about the candidates besides their pictures, yet they were asked to make judgments about how honest, moral, and kind the candidates appeared, as well as how the candidates made them feel, how likely they would be to vote for them, and the like. But there's a twist. Unbeknownst to the participants, the experimenters had used photoimaging software to morph participants' own photographs with the candidates' faces, using a ratio of 60 percent candidate to 40 percent participant, which was just subtle enough that the participants wouldn't be able to consciously detect the manipulation.... What was the point? Bailenson and colleagues wanted to know if making the candidates look more like the participants would be enough to change their judgments and preferences.
It was. Results showed that across the board, people had a stronger preference for the candidate whose photo was blended with theirs. No matter who the candidate was or what he stood for, the people rated the candidate whose picture had been morphed with their own as being more honest, moral, kind, and so forth --- and they indicated they would be more likely to vote for him.