A cool new study using virtual reality and ethical dilemmas has discovered that those with psychopathic traits will readily sacrifice the few for the good of the many.

But in a scenario that simulated inevitable harm against another human being, participants with strong psychopathic traits also used greater physical force, so we still wouldn't really want to be friends with them.

According to the Hare Psychopathy Checklist, to determine if someone has psychopathic traits, all we have to do is assess 20 traits with a strength of 0, 1 or 2, resulting in a maximum score of 40.

The cut-off for psychopathy is 30 points in the US, 25 points in the UK (where this study was conducted) and sometimes 25 points for research purposes.

These traits include impaired empathy, antisocial behaviour, callousness, impulsiveness, strong self-interest to the detriment of others, and a short attention span.

To assess the level of psychopathy of the 40 participants of their study, researchers from the University of Plymouth put together an electronic questionnaire from four self-reporting tests, including the Levenson Self-Report Psychopathy Scale (which you can take here if, like us, you got curious) and the HEXACO Personality Inventory (which you can take here).

The participants were then presented with a moral dilemma, both in a questionnaire and with a simulated action component. The latter used a robotic system called vBOT to provide haptic feedback to realistically simulate the feeling of, say, the resistance that would occur if you needed to… stab someone.

The moral dilemmas required the study participants to make the choice to physically kill someone for mercy or the greater good. For instance, sacrificing one person to save many, or mercy-killing an injured teammate who would otherwise be captured and tortured by the enemy.

For the second part of the study, the researchers recruited 25 members of the public, rather than the university student volunteers used in the first half.

These participants were presented with a full virtual reality version of the trolley dilemma that the researchers called the footbridge dilemma.

Using an Oculus Rift, the participants had to decide whether or not to push a man in front of a moving train, represented by an interactive sculpture they had to physically push, thus stopping the train and preventing it from ploughing into five bystander avatars.

The researchers found that all participants were more likely to make the sacrifice asked of them in the VR simulations than in the questionnaires. But disturbingly, those with more psychopathic traits used more physical force when stabbing their injured comrade or pushing the fake man in front of the moving train.

Interestingly, these trends were the same across both tasks, even though the first part of the study didn't have a visual component. This, the researchers noted, might require further study.

"This research highlights our proneness to moral inconsistency; what we say and what we do can be very different. For the first time, we demonstrate how personality traits can influence the physical power of our moral actions," said psychologist Kathryn Francis from the University of Reading.

"Importantly, the multidisciplinary approaches that we have used here, combining virtual reality, robotics, and interactive sculpture, place further empasis on the need to unite the sciences and the arts when investigating complex phenomena such as morality."

The research has been published in the journal Scientific Reports.