Left Brain, Right Brain
I appreciate Megan's grain-of-salt point (and Reihan's old take on studies of this sort), but I wouldn't be surprised at all if these results were at least roughly correct, and your average liberal has some cognitive advantage over your average conservative. How could it be any other way? It isn't just that the left, far more than the right, tends to tell brainiacs what they want to hear - that they were born to rule, that the world is just waiting to be reshaped for the better by their combination of smarts and expertise. (Though of course right-wingers sometimes give in to this temptation as well.) It's that we live in a society that makes an aggressive attempt to select for intelligence in the formation of its elite, and then educates that elite in a university system that is liberal to the core - not left-wing, necessarily, or not anymore, but certainly not conservative either, unless you think (as some fools do) that Thomas Friedman qualifies as a man of the right. The modern meritocracy has evolved to bring up most of its pupils to be Friedmanites, a minority to be Chomskyites, and a vastly smaller minority to be actual conservatives. Small wonder, then, that if you're brainy in America, you probably call yourself a liberal - you were raised that way, after all. Whereas conservatives are the stupid party - the party of the Boston phone directory, not the Harvard Faculty Club, with some crankish intellectuals thrown in for ballast. Thus we have been, and thus we shall always be, until the world - or at least America - is forever changed, and elanor and niphredil bloom no more east of the Sea.
(See - like I said, crankish.)