Benjamin & Shapiro (2007). This was presented in "Nudge" as evidence that voters make automatic and instinctive decisions about politicians and, generally speaking, don't reflect or deliberate much. I suggest that those instinctive reactions have evolved to be particularly important in judging people, their moods, likely behaviours or social connection. It's an animal response.
Interactive Democracy asks people to judge policies separately from candidates. I hope it would have some success at encouraging people to be reflective rather than reflexive.