Here’s a thought for this election week: If you are more disgusted by mucus and maggots, you’re a conservative. So says Nonpolitical Images Evoke Neural Predictors of Political Ideology, a recent article in Current Biology:

We carried out a passive picture-viewing experiment to test the hypothesis that nonpolitical but affectively evocative images elicit brain responses that predict political ideology as assessed by a standard political ideology measure. …

…

Accumulating evidence suggests that cognition and emotion are deeply intertwined, and a view of segregating cognition and emotion is becoming obsolete. People tend to think that their political views are purely cognitive (i.e., rational). However, our results further support the notion that emotional processes are tightly coupled to complex and high-dimensional human belief systems, and such emotional processes might play a much larger role than we currently believe, possibly outside our awareness of its influence. …

…

We proposed that conservatives, compared to liberals, have greater negativity bias, which includes both disgusting and threatening conditions in our study. Our finding that only disgusting pictures, especially in the animal-reminder category, differentiate conservatives from liberals might be indicative of a primacy for disgust in the pantheon of human aversions, but it is also possible that this result is due to the fact that, compared to threat, disgust is much easier to evoke with visual images on a computer screen.

Lastly, this study raises several important but unaddressed questions. First, while political ideology has effects on many forms of behavior (including, but not limited to, voting behavior), it is unknown whether it does so thanks to the neural differences in affective processing that we measured. Second, and relatedly, it is important also to know how individual differences in the capacity to regulate emotion, and the neural bases of that capacity, are related to political ideology. A third set of questions concerns the bearing of the present study on the development of biological measures of political ideology. While it is of use in a variety of settings to measure political ideology (political polls, for instance, typically include some measurement of it), it remains an open question whether biological measures could become more accurate, or more useful, than the tools (such as self-report measures) currently employed.

… The more we learn about the sensitivity of political ideology to subtle differences in affective response and their neural bases, the more we will know about the feasibility of useful and portable tools for ideology’s biological measurement. This would then raise a further and difficult ethical question about the circumstances, if any, in which it is appropriate to use such tools. And, finally, the present study raises important questions about the possibility of, and obstacles to, understanding and cooperation across divides in political ideology. Would the recognition that those with different political beliefs from our own also exhibit different disgust responses from our own help us or hinder us in our ability to embrace them as coequals in democratic governance? Future work will be necessary to answer these important questions.

(Via Slashdot, where the comments were even more inane than usual.)

Personally, I’m disgusted by people who want to block healthcare for the poor. Apparently that makes me a liberal. I’m unwilling to suggest that makes them maggots, but science?