So says the title of an interesting recent paper I stumbled on yesterday (ungated link; h/t Chris Bertram). Here's the abstract: 

Researchers have recently argued that utilitarianism is the appropriate framework by which to evaluate moral judgment, and that individuals who endorse non-utilitarian solutions to moral dilemmas (involving active vs. passive harm) are committing an error. We report a study in which participants responded to a battery of personality assessments and a set of dilemmas that pit utilitarian and non-utilitarian options against each other. Participants who indicated greater endorsement of utilitarian solutions had higher scores on measures of Psychopathy, machiavellianism, and life meaninglessness. These results question the widely-used methods by which lay moral judgments are evaluated, as these approaches lead to the counterintuitive conclusion that those individuals who are least prone to moral errors also possess a set of psychological characteristics that many would consider prototypically immoral.

This conclusion is very much along the lines of some of my recent LW comments (for example, those I left in this thread). To me it seems quite obvious that in the space of possible human minds, those that produce on the whole reasonably cooperative and reliably non-threatening behavior are overwhelmingly unlikely to produce utilitarian decisions in trolley-footbridge and similar "sacrificial" problems. 

Of course, what people say they would do in situations of this sort is usually determined by signaling rather than a realistic appraisal. Kind and philosophical utilitarians of the sort one meets on LW would be extremely unlikely to act in practice according to the implications of their favored theories in real-life "sacrificial" situations, so their views are by themselves not strong evidence of antisocial personality traits. However, actually acting in such ways would be, in my opinion, very strong evidence for such traits, which is correctly reflected in the typical person's fear and revulsion of someone who is known to have acted like that. I would venture to guess that it is in fact the signaling-driven disconnect between people's endorsement of utilitarian actions and the actual decisions they would make that makes the found correlations fairly low. (Assuming also that these tests really are strong indicators of antisocial personalities, of course, which I lack the knowledge to judge.)

(Also, endorsement of utilitarianism even just for signaling value causes its own problems, since it leads to political and ideological support for all sorts of crazy ideas backed by plausible-sounding utilitarian arguments, but that's a whole different issue.)

Here is also a full citation for reference: “The mismeasure of morals: Antisocial personality traits predict utilitarian responses to moral dilemmas”, by Daniel M. Bartels and David A. Pizarro, Cognition 121 (2011), pp. 154-161.

Edit: As Wei Dai points out in a comment, I should also add that some of the previous literature cited by Bartels and Pizarro has concluded that, in their words, "individuals with higher working memory capacity and those who are more deliberative thinkers are... more likely to approve of utilitarian solution." One the face of it, taken together with the conclusions of this paper, this would mean that propensity for utilitarian responses may stem from different causes in different individuals (i.e. deliberative thinking versus antisocial traits).

My own hypothesis, however, is that deliberative thinking leads to verbal utilitarian responses that are likely due to signaling, and that propensity for actual utilitarian "sacrificial" acts would have a much weaker link to deliberative thinking and a much stronger link to antisocial traits than mere utilitarian statements. Unfortunately, I don't know how this could be tested empirically in an ethical manner.