Would you choose to kill someone to save the lives of several others? Well, nine out of 10 people say "yes", a new study has found.

In the morality study by researchers from the Michigan State University, subjects donned a head-mounted device that placed them in a 3D setting with realistic digital characters. They also wore sensors attached to their fingertips to monitor their emotional arousal.

In the virtual world, participants were standing near a railroad switch where two sets of tracks veered off from each other. As a coal-filled boxcar approached, the subjects could choose to do nothing and allow the boxcar to kill five hikers, or pull a joystick "switch" to divert the train to a different track, where it would kill only one hiker.

Of the 147 participants, 14 allowed the boxcar to kill the five hikers; eleven of these subjects did not pull the rerouting switch at all, while three did so but then changed their minds and returned it to its original position.

But, 90 per cent, or 133 participants, chose to pull the switch that diverted the boxcar to kill just one hiker.

The results suggest that people are generally willing to violate a moral rule if it means minimising harm to others, the researchers said.

"What we found is that the rule of 'Thou shalt not kill' can be overcome by considerations of the greater good," study author Carlos Navarrete was quoted as saying by LiveScience.

The study, published in the journal Emotion, is modeled after the "trolley problem," a moral dilemma that philosophers have contemplated for decades. But, the visual and auditory aspects of the new experiment's 3D environment make the consequences of either decision more realistic to the subjects than past studies, the researchers said.

The subjects who did not pull the switch (and killed five hikers) were more emotionally aroused than those who chose to save the five hikers by killing one, the researchers said.

Although they do not know the reasons behind the higher arousal, Navarrete suggested that it may be because some people freeze up in emergency situations.

"I think humans have an aversion to harming others that needs to be overridden by something," Navarrete said.

"By rational thinking we can sometimes override it, by thinking about the people we will save, for example. But for some people, that increase in anxiety may be so overpowering that they don't make the utilitarian choice, the choice for the greater good," he added.