Jen Wright at Experimental Philosophy:

… I’m writing this post because I found something even more interesting…and puzzling. Leaving people’s actual looking behavior aside, I found a very powerful effect — consistent across all the vignettes — for which side of the screen the potential victim (the fat guy or the baby) was on. When the victims were on the right-side of the screen, people’s would and should judgements were significantly higher (i.e., they were more willing to, and thought more strongly that they should, kill the victim to save the others), than when they were on the left-side of the screen.

So, does anyone have any suggestions as to what might explain this finding?

My guess is that it’s related to the previous findings that people tend to place active people on the left of passive people in pictures (though it seems to vary across languages). The easiest interpretation is that it seems more moral to sacrifice passive people than active ones. That would also fit with the pattern I pointed out before in our moral intuitions, that moral concern is highly contingent on whether we can be rewarded or punished by the beneficiary of our ‘compassion’.