New research from Aarhus University in Denmark shows that political partisanship is rooted in affective, physiological processes that cause partisans to toe the party line on policies and issues, regardless of policy content.

Previous research has shown that party identifiers are more inclined to agree with policy proposals that are proposed by their own party, independent of the content of the proposal. If the same proposal is issued by a competing party, they will be inclined to respond negatively to it.

Until now, however, it has remained unclear whether this partisan bias is based on rational considerations or on more intuitive, affective reactions. Now researchers from Aarhus University in Denmark have established that only party supporters who are affectively and physiologically engaged in their party show evidence of partisan bias. Their study has been published in the journal PLOS ONE under the title "Physiological Responses and Partisan Bias."

Measuring feelings

Together with two students from Aarhus University, Professor Michael Bang Petersen has measured activity in the sympathetic nervous system --