Must be all the pot the hippies smoke. That tends to calm the nerves.
Of course this isn't conclusive. One of the criticisms of the experiment is that the emotion being evoked by the photos was perhaps more along the lines of revulsion or confusion than it was of fear. That would only mean that conservatives are less likely to win a game of third-grade gross out. Another criticism is that the more fearful mindset of the conservative group was actually part of the same social upbringing that led to their political beliefs.
But it does seem that the Republican Party has really been playing the fear card more so than Democrats in the recent past. Fear of criminals. Fear of immigrants (the great xenophobia). Fear of queers (or as I like to say, Queers for Fears). Fear of terrorists. Fear of Bill Clinton's penis. Fear of Hillary Clinton's penis. Fear of a black guy with a funny name. Their campaigning tends to draw a lot on speaking to the fear of the other or the different.
Of course, that's not to say that all Republicans are pansies who look at the world only in terms of fight or flight. I'm sure many end up there through logical or social means without actually being any more or less fearful than normal. That also probably goes both ways. Still it could be good in understanding where people on the other side of the debate are coming from, as the guy who headed the research pointed believed.
And by the way, that researcher claimed he wasn't looking to discredit Republicans. He said that the research could just as easily be used to call liberals out of touch or naive of danger, but, honestly, that's just not as funny.