Last Updated: Friday, Oct 07, 2016 12:00:00 AM
We used functional neuroimaging to study the neural responses of 30 committed partisans during the U.S. Presidential election of 2004. We presented subjects with reasoning tasks involving judgments about information threatening to their own candidate, the opposing candidate, or neutral control targets. Motivated reasoning was associated with activations of the ventromedial prefrontal cortex, anterior cingulate cortex, posterior cingulate cortex, insular cortex, and lateral orbital cortex. As predicted, motivated reasoning was not associated with neural activity in regions previously linked to cold reasoning tasks and conscious (explicit) emotion regulation. The findings provide the first neuroimaging evidence for phenomena variously described as motivated reasoning, implicit emotion regulation, and psychological defense. They suggest that motivated reasoning is qualitatively distinct from reasoning when people do not have a strong emotional stake in the conclusions reached.
Neural Bases of Motivated Reasoning: An fMRI Study of Emotional Constraints on Partisan Political Judgment in the 2004 U.S. Presidential Election , Westen et al, 2006, MIT, http://www.wcas.northwestern.edu/nescan/WestenBlagovHarenskiKiltsHamann_2006.pdf
I've basically given up on political (and probably most other) debates unless I can first determine a person is hyper-rational, hyper-skeptical, and/or hypoegoic. The only alternative is emotional manipulation (i.e. debating nasty), which seems wrong.