Abstract
When de ned in terms of social identity and a ect toward co-partisans and op-posing partisans , the polarization of the American electorate has dramatically increased .
We document the scope and consequences of a ective polarization of partisans using implicit , explicit and behavioral indicators .
Our evidence demon strates that hostile feelings for the opposing party are ingrained or automatic in voters' minds , and that a ective polarization based on party is just as strong as polarization based on race .
We further show that party cues exert powerful e ects on non-political judgments and behaviors . Partisans discriminate against opposing partisans , and do so to a degree that exceeds discrimination based on race .
We note that the willingness of partisans to display open animus for oppos-ing partisans can be attributed to the absence of norms governing the expression of negative sentiment and that increased partisan a ect provides an incentive for elites to engage in confrontation rather than cooperation .
Full Article：
http://pcl.stanford.edu/research/2014/iyengar-ajps-group-polarization.pdf