A study published by Virginia Tech professor P. Read Montague in Current Biology indicates that brain scans taken while people look at disturbing images can accurately predict their political leanings.
Titled, "Nonpolitical Images Evoke Neural Predictors of Political Ideology," the research was able to sort participants into liberal and conservative categories based on their brain's reaction to a picture of a mutilated animal carcass. However, while subconscious brain activity was divided by political affiliation, that activity did not correlate to the subjects' conscious experience of the photo.
Previous research has suggested that conservatives are more easily disgusted than liberals, while libertarians are more like liberals in this regard, and are less likely to be grossed out.