Study shows as people non-consciously categorize others by political affiliation, they ignore race—but not age, gender

Beatles versus Rolling Stones. Ironman versus the Incredible Hulk. Deep dish versus thin crust. Such differences of opinion among family and friends rarely end in serious squabbles. Let the conversation turn to political parties, however, and lively disagreements can become downright ugly.
Why is it that even among the people we care about most, differences in political affiliation often result in awkwardness and discomfort, and pushed far enough, can feel like a threat to the entire relationship?
The answer may lie in research conducted at UC Santa Barbara's...