Reading an article in the LA Times today, I learned something exciting: political differences in thought happen in the brain. At least that’s what a new study published in Nature Neuroscience(1) purports to show, though I hear that the next issue of the journal will contain critical responses from Descartes, Malenbranche, and Eccles.
Seriously though, the paper by Amodio et al. takes as its launching point the large body of evidence that political conservatives and liberals differ on personality dimensions related to openness to experience, tolerance of uncertainty, and cognitive complexity. It stands to reason that such differences in cognitive style manifest themselves in the brain (pace Descartes), but it doesn’t really suggest where in the brain. However, the relationship between these differences and conflict monitoring (a much more tenuous relationship, in terms of empirical support, I should note). Conflict monitoring is, in turn, seen as a form of cognitive control, or self-regulation, and is associated with a specific brain region: the anterior cingulate cortex (ACC; the blue part in the image below), part of the prefrontal cortex. Perhaps liberals and conservatives show differences in the activity of the ACC, then?
Wait, what’s conflict monitoring? Some researchers have hypothesized that there’s a system in the brain tasked with looking for conflicts in information processing. This system is necessary, they argue, because with all of the processing going on inside our heads in parallel, there’s an inherent risk of “crosstalk interference” (2). That is, two streams of information that start out in different places might, at some point, cross paths. This leads to competition, conflict, and ultimately interference that can negatively affect performance. It’s important, then, to keep track of such conflicts, or potential conflicts at least, so that they can be avoided.
Now, this isn’t quite the definition of conflict monitoring that Amodio et al. put forward in their paper, but given that it’s the definition that the literature on conflict monitoring itself uses, and that the major theory linking cognitive control (and thus, self-regulation) to conflict monitoring uses this definition as well, I’m going to go with it. And to be honest, it’s not immediately clear how conflict monitoring in that sense and differences in liberal and conservative personality are related, but I can let that pass for now… OK, no I can’t really. Let’s face it, the intro to this paper, which is necessarily short because it’s only a “brief communication,” is terrible. I have no idea why they hypothesized a relationship between, say, tolerance for uncertainty and conflict monitoring. That hypothesis feels about as non sequitur as this:
Given that these associations between political orientation and cognitive styles [those described above – Chris] have been shown to be heritable, evident in early childhood, and relatively stable across the lifespan, we hypothesized that political orientation may be associated with individual differences in a basic neurocognitive mechanism involved broadly in self-regulation. (p. 1)
Well alrighty, then. Eye color is heritable, evident in early childhood, and relatively stable across the lifespan, but I’ve never seen someone associate it with self-regulation. Anyway, whatever the hidden logic behind the association of differences in cognitive style related to political orientation and conflict monitoring, here’s what they did.
They first had participants complete a political questionnaire, which included a question about whom, if anyone, they voted for in the 2004 presidential election, along with a scale ranging from -5 (“extremely liberal”) to 5 (“extremely conservative”). In previous research, that scale has correlated very strongly with voting behavior, and in their sample (43 right-handers), it was strongly correlated with 2004 voting. So it’s a pretty good measure of political orientation to the extent that liberals vote for Democrats and conservatives for Republicans.
Next they had participants complete a Go/No-Go task. In their version, participants were shown an M or a W, and told to respond only to one or the other by pressing a key (half the participants responded to M’s, and half to W’s). Responding to the target letter is the Go part, and not responding to the other letter is the No-Go part. In order to make responding the default, 80% of the 500 trials each participant saw were Go trials. This makes is so that when a No-Go trial pops up, participants face potential crosstalk interference. One system, the one that treats Go responses as the default, is trying to make the participant press the button, while the other system, recognizing that the No-Go letter has appeared, is trying to inhibit a response. As a result of this interference, the conflict monitoring system should kick in.
Now, we know that conflict in these sorts of tasks leads to increased activity in the ACC, so to look for differences between liberals and conservatives, Amodio et al. measured event related potentials (ERPs) there. And since they published the paper, you can probably guess that they found differences. Specifically, during the No-Go tasks, when the conflict monitoring system should be active and screaming, “Oh shit!” they found more neural activity in the ACC in liberals than in conservatives. Consistent with this, liberals were more accurate in the No-Go trials than conservatives. Thus they conclude:
Our results are consistent with the view that political orientation, in part, reflects individual differences in the functioning of a general mechanism related to cognitive control and self-regulation. Stronger conservatism (versus liberalism) was associated with less neurocognitive sensitivity to response conflicts. At the behavioral level, conservatives were also more likely to make errors of commission [i.e., pressing the button in No-Go trials -Chris]. (p.2)
Exactly what this means, I can’t really say. I’m not sure that it says much about the relationship between political orientation and self-regulation, but if it does, perhaps it provides a clue to the cognitive mechanisms underlying the personality variables associated with openness and uncertainty. The behavioral differences that result from those personality variables might also be related to this studies findings. Are conservatives more likely to make errors of commission in a wide variety of situations in which habitual responses are in place, for example? Only future research will tell. It shouldn’t, however, be taken as saying anything about the relative levels of intelligence of liberals and conservatives (though I’m pretty certain that it will, by people on both sides). So far, all it really says is that differences in thinking happen in the brain.
UPDATE: The Neurocritic gets all neurocritical.
1Amodio, D.M., Jost, J.T., Master, S.L., & Yee, C.M. (2007). Neurocognitive correlates of liberalism and conservatism. Nature Neuroscience.
2Botvinick, M.M., Braver, T.S., Barch, D.M., Carter, C.S., & Cohen, J.D. (2001). Conflict monitoring and cognitive control. Psychological Review, 108(3), 624-652.