It’s a moral and ethical problem that has been studied before: you see a train heading towards five hikers and you have the power to save them. Just pull a switch to make the train swerve out of the way on another track. BUT you’ll kill another hiker who won’t see the train coming at all. What do you do? Intervene? Or no?

Variations on this have vexed philosophers (and their students) for decades. Carlos David Navarrete, an evolutionary psychologist at Michigan State University, decided to apply a little technology to the problem.

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He created a 3D, virtual environment in which subjects would experience the actual situation. Each subject was given a joystick that would throw the (virtual) switch, thus saving five people by sacrificing one. To monitor their emotional states, he attached sensors to the subjects’ fingertips. This is the first time anyone has measured a “physical” response to the ethical dilemma.

The result itself wasn’t that surprising: of the 147 participants, 133 (90.5 percent) pulled the switch to divert the train, resulting in the death of the one person. Fourteen participants allowed the train to kill the five. Eleven participants did not pull the switch at all, while three pulled the switch but then returned it to its original position. All this is consistent with earlier studies that didn’t use virtual reality.

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The new data shows, however, that participants who did not pull the switch were more emotionally aroused. Nobody knows why that is. It may be because people “freeze up” during highly anxious moments, such as when soldiers fail to use their weapons in battle, Navarrete said in a press release.

For Navarette, the interesting thing was that while most people made the utilitarian choice -– sacrificing one to save many –- humans have to overcome a natural aversion to hurting other people. Rationalizing the choice (weighing the costs and benefits) can help people overcome that to make tough decisions like that. But in some cases, a person can get so anxious that they can’t make a decision at all, or make the wrong one.

Image / Video: Michigan State University