University of Pennsylvania professor Diana Mutz’s book "Hearing the Other Side: Deliberative versus Participatory Democracy looked at survey evidence as to how often people had conversations with others of differing political viewpoints. In her words:
One logical conjecture would be to expect this form of political behavior to be much like any other. In other words, it would be disproportionately the province of well-educated, high-income populations. Indeed, the frequency of general political discussion tracks closely with these characteristics of high socioeconomic status. But the correlates of cross-cutting conversation are strikingly different. As shown in Figure 2.3, there are clear patterns of difference with respect to race, income, and education, but they are not in the usual directions. Nonwhites are significantly more likely to engage in cross-cutting political conversation than whites. And as income increases, the frequency of disagreeable conversations declines. Exposure to disagreement is highest among those who have completed less than a high school degree and lowest among those who have attended graduate school.
As sociologist William Weston notes in discussing Mutz’s findings:
I can testify to how easy it is for conversation among academics, the most educated group of people, to turn into a one-position echo chamber. Liberalism is taken to be an IQ test, and the rare conservative is encouraged to be quiet or go elsewhere. For political disagreement I go to the coffee house, which in our town draws a broader range of people than the faculty club contains.
Of course, one explanation would be that what looks like herd behavior and social conformity is really just what happens when a bunch of superior intellects independently settle on the objectively correct viewpoint. But that’s rather a self-serving explanation, isn’t it?