Most People Would Kill 1 Person to Save 5 Others

Would you choose to take someone's life in order to prevent the deaths of several other people? A new study using 3D simulations found that nine out of 10 people would answer "yes."

In the experiment, subjects donned a head-mounted device that placed them in a 3D setting with realistic digital characters. The participants 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 reroute the boxcar to a different track, where it would kill one hiker.

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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. About 90 percent, 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 minimizing harm to others, according to the researchers.

"What we found is that the rule of 'Thou shalt not kill' can be overcome by considerations of the greater good," study researcher Carlos David Navarrete, an evolutionary psychologist at Michigan State University, said in a statement.

The boxcar study is modeled after the "trolley problem," a moral dilemma that philosophers have contemplated for decades. However, 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. Although the researchers do not know the reason for 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."

The study was published Nov. 21 in the journal Emotion.

You can follow LiveScience writer Remy Melina on Twitter @remymelina. Follow LiveScience for the latest in science news and discoveries on Twitter @livescience  and on Facebook.