(I promised I’d get to this.)
Amusingly, Peter Frost, over on Evo and Proud, just recently posted, “Are liberals and conservatives differently wired?“, which describes some of the recent studies on the subject and draws conclusions broadly counter to my own. I thought you should know.
Actually, I suspect that most of the reason for or ‘disagreement’ is that we are using a different organizing schema to class people as “liberal” or “conservative.” Frost is starting with people’s self-reported affiliation, noting the differences found in the experiments, and then noting the (rather large) ethnic differences between the two groups and speculating that much of the observed difference may be primarily ethnic, rather than some grand approach to principles.
I started by first controlling for race, because otherwise (IMO) we end up smushing most of the non-whites into incorrect categories by assuming that they are voting for candidates and policies for the same reasons as whites. IE, “attitude towards blacks” and “attitude toward people who are ethnically different from yourself” might be roughly synonymous if you happen to be a white person who lives near black people, but they’re not at all synonymous if you happen to be a black person. Of course black people tend to vote for candidates who seem most likely to not be racist against black people, but that’s not the same as being liberal. (That’s just common sense.) However, since we live in a country where the majority of people are white, we tend to default toward the white POV when talking about political affiliation, and so many people who are not actually liberal at all may call themselves liberal just because they vote for the Democrats (and possibly, though I suspect less likely, vice versa.)
Any study looking for neurological differences between “liberals” and “conservatives” that just uses self-reported political orientation and doesn’t control for ethnicity seems rather dubious. If it turns out that all of my understanding of neuroprocessing is compromised, I’m going to be sad and will have to re-research everything.
Once you factor out the wonky racial dynamics, I think there is actually such thing as more or less liberal people. In the case of the British study Frost cites, I strongly suspect that the Muslims who vote Labour are actually quite conservative. Likewise, African Americans have very high rates of church attendance and strike me as fairly conservative overall, though not as conservative as most Muslims. The same is more or less also true of American Hispanics and Asians, while most white Europeans strike me as more liberal than American whites.