What is surprising is that it happens on a molecular level.
Mirror neurons are now famously tied to empathetic reactions in people (autistics have some problem with them) but it's not generally well understood what they do. Basically, the incredible finding is that any action you witness, you have an urge to do. We know this because the muscular activity required to do those things is activated and can be sensed, and because the neural patterns that occur when an act is performed also run when that act is seen from afar. Sounds crazy, no? The only reason we aren't all acting out each other's behaviour is because of some other neurons that say "Whoa, dude." The whoa-dude neurons: you read it here first.
So this new research by Glenn Fox and Jonas Kaplan at USC shows that mirror neurons fire differently depending on how well we regard the person doing the action being viewed. How did they know what the study participants thought of the people they watched? Because they were all Jewish males, and they were given backgrounds of the people they were watching which varied significantly only in their degree of anti-Semitism. The unlikeables all were unrepentant neo-Nazis, not a favorite group of Jewish males. But to be sure, they also completed questionnaires rating likeability when they were done.
Other studies have shown differences in neural activity based on the race. This is the first one, the authors claim, that does so based on attitude, although they cite similar findings from a study that saw a difference in touch reactions brought on by political party affiliation.
The authors don't know the significance of the different neural pattern, only that it occurs (which is weird enough). They also caution us not to overgeneralize: "The main focus of this study was specifically to examine interpersonal liking as it is derived from social group membership, in a circumstance that is free from social stigma against disliking the outgroup member."
But I can't help it. I don't like my neighbour because of his noisy dog. It's intriguing to know that when I see him reaching for his morning paper, my mirror neurons are expressing their disdain. Maybe I don't want to emulate him. Maybe the whoa-dude neurons have to do less work to stop me. Maybe my revulsion causes a set of different proto-sensorimotor reactions altogether, like heaving or swinging a baseball bat.
Now there's a research project for someone.