This election is divisive, both in and between parties. Unfortunately, our brains don’t work too well in groups.
Links for the Curious
Evidence of an increasing division between political parties in the US - http://www.annualreviews.org/doi/abs/10.1146/annurev.polisci.9.070204.105138
Tajfel et al’s 1971 paper demonstrating that even totally arbitrary grouping does weird stuff to human brains - http://www.morilab.net/gakushuin/Tajfel_et_al_1971.pdf
A study about how ingroup/outgroup bias can color what characteristics people are quick to assign to their ingroup/outgroup - http://www.sciencedirect.com/science/article/pii/S0022103199913999
Evidence that we show greater affinity for ingroup members who promote the group’s distinctiveness over those who try to be more evenhanded - https://www.researchgate.net/publication/234023326_Castelli_Carraro_EJSP_2010
A study showing that simply framing a political argument as coming from the ingroup increases its acceptance dramatically - http://www.sciencedirect.com/science/article/pii/S0022103116301056
Groups also make us prone to riskier behavior, arriving at more extreme conclusions together than we would on our own - https://deepblue.lib.umich.edu/handle/2027.42/108371