Is it ethical to kill one person in order to save five?  Known as the “trolley problem” – which poses the question in the context of diverting a trolley from a path that would hit five people to a path that would hit one – this is a hotly debated question in ethics and philosophy.

A second question is how many people would actually kill one person in order to save five (i.e. act on their ethical conviction)?

Researchers from Michigan State University simulated this problem in a 3D virtual world “with the sights, sounds and consequences of our actions thrown into stark relief.”

Participants, wearing head-mounted devices, were stationed at a railroad switch in the virtual world.  On their right, five people were hiking along railroad tracks.  On their left, one person was hiking.  

The train was headed right towards the five people.  The participants were given the opportunity to switch it to the left towards the one person or do nothing and let it hit the five people.

A 2-D example of the experiment and photos from the actual 3D experiment are seen below.



About 90 percent of the study participants chose to divert the train to kill one person to save five. About 9 percent chose to do nothing and let the train kill five people.  A few participants (less than 1 percent) initially diverted the train towards the five people before switching it back towards the one person.

Interestingly, participants who did not pull the switch recorded higher emotionally arousal on the sensors attached to their fingertips.

Carlos David Navarrete, the lead researcher of the study, speculated that these people may have frozen up, akin to a solider failing to fire his weapon in battle.

I think humans have an aversion to harming others that needs to be overridden by something. By rational thinking we can sometimes override it - by thinking about the people we will save, for example, said Navarrete.

That is, even if some people think it is ethical to kill one to save five, they may not have the emotional fortitude to act upon that conviction.