Are Republicans smarter than Democrats, conservatives dumber than liberals?

There was a big uproar over a fake study once where someone claimed red states had lower average IQs than blue states did. I thought this was stupid -- a well-designed study (even a fake one) would look at individuals and their party preferences, not whole states. I've noticed The Inductivist does a lot of work with the General Social Survey, so I followed his lead.

After doing so, I found that Half Sigma once did something similar. He kept his results to party ID, where mine also include political ideology. He also looked at trends (concluding Democrats are getting smarter relative to Republicans), where I just used the current data.

The GSS does two measures of IQ, vocab and reasoning. It also asks for party preference. Running a simple correlation matrix, I found that the number of words someone got right on a vocab test correlated with their proximity to the Republican side of the spectrum (.111). The reasoning test is broken down into individual questions, and most aren't significantly linked to party, but the ones that are point the same way. Republicans are smarter.

The weird thing is that when I replace political party with political ideology (conservative/liberal), I get the opposite result, though weaker. There's a -.029 correlation with vocabulary. (None of the reasoning tests gives a significant result.)

Why the different results? The first stereotype to come to mind is Southern Democrats who have low IQs and consider themselves conservative. And the Republican/conservative, Democrat/liberal link isn't as strong as you'd think for most Americans -- there's only a .310 correlation.

It's all quite disconcerting, because I consider myself much more conservative than Republican.