The field of social psychology has long been focused on how social environments affect the way people behave. But social psychologists are people, too, and as the United States has become increasingly politically polarized, they have grown increasingly interested in examining what drives these sharp divides: red states vs. blue states; pro-Iraq war vs. anti-Iraq war; pro-same-sex marriage vs. anti-same-sex marriage. And they have begun to study political behavior using such specialized tools as sophisticated psychological tests and brain scans.
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The new interest has yielded some results that will themselves provoke partisan reactions: Studies presented at the conference, for example, produced evidence that emotions and implicit assumptions often influence why people choose their political affiliations, and that partisans stubbornly discount any information that challenges their preexisting beliefs.

Emory University psychologist Drew Westen put self-identified Democratic and Republican partisans in brain scanners and asked them to evaluate negative information about various candidates. Both groups were quick to spot inconsistency and hypocrisy — but only in candidates they opposed.

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