Would You Kill One Person to Save Five? New Research on a Classic Debate

by John Cloud

Time
December 5, 2011

Imagine you are a train-yard operator who sees an out-of-control boxcar running down a track that five workers are repairing. The workers won't have time to get out of the way unless you flip a switch to change the car to another track. But another worker is on the second track. You have just seconds to make a decision: let the five workers die — or kill the one. What do you do?

This dilemma is a famous philosophical conundrum that was originally called the "trolley problem." Now a team from Michigan State University's psychology department has used virtual-reality technology to test how we respond psychologically and physiologically when faced with this problem.

The two opposing philosophical approaches to the trolley problem are the utilitarian one (kill one guy in order save the others) and the do-no-harm approach (let God or nature take its course, but don't make an active choice to kill another person).

In many years of surveys, the vast majority of people — usually about 90% — have chosen to kill the one and save the five. But until now, there's never been a study examining how people would react in a lifelike setting with real-looking potential victims.

In the Michigan State study, led by psychologist David Navarette, the 147 participants made their choice while wearing a head-mounted virtual-reality device that projected avatars of those who could die. (Watch a simulation here.) One chilling factor of the test: the potential victims were screaming as the boxcar approached.

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See more about the project