Riffing again off a comment thread from a recent post on verbal intelligence by race and political orientation, average Wordsum scores among Democrats, independents, and Republicans by self-described political orientation follow. Wordsum is a ten-question vocabulary test with results that correlate with IQ at .71–quite rigorous for the social sciences, but of course not perfect. To avoid language fluency issues, results are restricted to respondents born in the US. One standard deviation is 1.9 points, so the graph’s ceiling is roughly 1 standard deviation above the population mean and the floor 1 standard deviation below it:
This helps explain why, intraparty, Democrats tend not to be much impressed by conservatives and Republicans tend not to be much impressed by liberals. In the former case, there is a significant racial component to the distribution.
Perhaps in the latter case liberal Republicans tend to be people who identify as Republican because that’s how they were raised but who haven’t put their beliefs to the test so have default values broadly in line with the broader zeitgeist. Smarter people raised Republican but with liberal beliefs, by contrast, calibrate their party affiliation in accordance with their beliefs.
The difference between liberal Democrats and conservative Republicans is modest, about one-tenth of one standard deviation. Converted to IQ, this is a gap of a point or two. Given that those on the left tend to do relatively better with verbal intelligence than with visuo-spatial intelligence and those on the right the opposite, it’s close to a wash.
GSS variables used: WORDSUM, BORN(1), POLVIEWS(1-3)(4)(5-7), PARTYID(0-1)(2-4,7)(5-6), YEAR(2000-2018)