Towards a neuropsychology of political orientation: exploring ideology in patients with frontal and midbrain lesions

Hannah Nam H, Jost JT, Meager MR, Van Bavel JJ. Towards a neuropsychology of political orientation: exploring ideology in patients with frontal and midbrain lesions. Phil. Trans. R. Soc. B 20200137, Jan 20201. https://doi.org/10.1098/rstb.2020.0137

How do people form their political beliefs? In an effort to address this question, we adopt a neuropsychological approach. In a natural experiment, we explored links between neuroanatomy and ideological preferences in two samples of brain lesion patients in New York City. Specifically, we compared the political orientations of patients with frontal lobe lesions, amygdala lesions and healthy control subjects. Lesion type classification analyses revealed that people with frontal lesions held more conservative (or less liberal) beliefs than those with anterior temporal lobe lesions or no lesions. Additional analyses predicting ideology by extent of damage provided convergent evidence that greater damage in the dorsolateral prefrontal cortex (dlPFC)—but not the amygdala—was associated with greater conservatism. These findings were robust to model specifications that adjusted for demographic, mood, and affect-related variables. Although measures of executive function failed to mediate the relationship between frontal lesions and ideology, our findings suggest that the prefrontal cortex may play a role in promoting liberalism. It is possible that the dlPFC is a critical region for the development of liberal ideology. Our approach suggests useful directions for future work to address the issue of whether biological developments precede political attitudes or vice versa—or both.

4. Discussion

We found that frontal lobe lesion patients reported more conservative (or less liberal) political orientation than patients with damage to their anterior temporal lobe and healthy control participants with no history of brain damage. ATL lesion patients were as liberal as healthy control participants. These findings were robust to various model specifications, including those that adjusted for demographic, mood and affect-related variables. Moreover, the extent of damage in the dlPFC was positively associated with self-reported conservatism, whereas the extent of damage in the amygdala attributable to ideological extremity, which was unrelated to brain damage. The results of our study suggest that the prefrontal cortex may be a region that is integral to the expression of liberal political attitudes, insofar as damage to this brain region was associated with a more conservative orientation. The results are also suggestive of the possibility that the amygdala is an important structure for the development of conservative attitudes, given that ATL lesion patients were less conservative than frontal lobe lesion patients. This would be consistent with prior work linking greater amygdala volume to conservatism [16] and system justification [46]. At the same time, ATL lesion patients were no more liberal than healthy control participants, and the degree of amygdala damage was not associated with ideology, so at least in this context, it appears that the amygdala per se is not a necessary structure for conservatism. We hope that future work will be able to assess causal pathways more directly, perhaps by obtaining information about political attitudes before and after a planned surgical resection of brain tissue. Based on research linking (a) political liberalism to cognitive flexibility and control and (b) executive functioning to frontal lobe activity, we explored the possibility that patients with frontal lobe lesions were more conservative due in part to diminished executive functioning. However, this possibility was not borne out in this study. We examined performance on three established tests of executive function; the differences we observed were in the expected direction, but they were not statistically significant, possibly because our sample was too small to provide sufficient statistical power. It is possible that specific cognition type could be useful to consider. For instance, it may be that social or identity-related cognitive functions are especially pertinent when it comes to linking frontal cortex function to political ideology (see [9]). Future research would do well to investigate these possibilities in larger samples, possibly by combining several small samples of patients with different types of lesions. Some have argued that the study of political ideology requires the measurement of multiple dimensions, such as social and economic attitudes [59]; but see [76]). We had no specific predictions regarding social versus economic dimensions of ideology (as opposed to overall liberalismconservatism), but we did administer individual items to measure them separately. We found no evidence that brain lesions were differentially linked to social versus economic attitudes, nor to ideological extremity on any of these dimensions. Nevertheless, future research based on larger (and more diverse) samples would do well to explore these possibilities. In conclusion, we have undertaken a neuropsychological investigation of political orientation by focusing on patients with different brain lesions. Our findings speak to the question of whether certain brain regions are necessary for the development of specific political beliefs, opinions and values. It may be worth noting that by exploring brain lesions we are not in any way suggesting that holding liberal or conservative attitudes is reflective of neural deficits or damage. Rather, the lesion method illuminates which neuroanatomical regions—and the cognitive functions related to them—may be necessary for understanding the development of political ideology. It is also important to keep in mind that studies of brain structure, including lesion studies, do not rule out effects of neural reorganization and malleability [77]. Accordingly, we strongly caution against deterministic or essentialized interpretations of our research (see [78]). Moreover, we theorize that the relationship between neurobiology and ideology is dynamic and reciprocal (see [4]), bearing in mind Nudo’s [77] observation that ‘behavioral experience is the most potent modulator of brain plasticity’ (p. 1). Along these lines, we look forward to future research that specifies the ways in which ideological experiences may shape the structures and functions of the human brain.