The Trolley Problem Has Been Tested In Real Life, And The Results Are Surprising


Tom Hale


Tom Hale

Senior Journalist

Tom is a writer in London with a Master's degree in Journalism whose editorial work covers anything from health and the environment to technology and archaeology.

Senior Journalist


No humans (or mice) were harmed in the making of this experiment. demamiel62/Shutterstock

Picture this: you see a train steaming straight towards five people who are tied to the track. By your side, there's a lever that can divert the speeding train onto another track. However, on this second track, there is one person tied up.

Would you pull the level and actively kill someone to save the lives of five other people?


It may or may not surprise you to hear that people react totally differently depending on whether this problem is hypothetical or actually involves real lives. 

For the first time ever, psychologists from Ghent University in Belgium recreated this dilemma in real-life enactment using mice in lab conditions. Their surprising findings were recently published in the journal Psychological Science.

This ethical head-scratcher is known as The Trolley Problem, a famous thought experiment designed to get you thinking about the moral difference between actively killing and passively letting people die. Philosophically speaking, a utilitarian would argue it’s morally right to pull the lever because it is the action that results in the least amount of harm, but a deontologist would argue it’s morally wrong to pull the lever because the action means you are intentionally engaged in harming someone.

All in all, it's a devilishly problematic choice. 

Zapyon/Wikimedia Commons CC BY-SA 4.0

The researchers gathered 200 people and told them they were about to zap a cage of five mice with a strong electric shock. Participants were told if they pressed a button then the electroshock would be diverted to a cage containing one mouse instead. (The mice were not actually shocked in the end, it was just an empty threat. Phew). Before this, though, they asked the participants how they thought they would hypothetically react to this problem.

The results showed 66 percent of people would press the button in a hypothetical scenario, according to New Scientist. However, when the chips were down and the real mice were in front of them, 84 percent of people chose to press the button and actively zap the one mouse. You might assume that people would think more emotionally in a real scenario and more rationally in abstract scenarios, but this was not what they found at all.

Crucially, the study showed that people think differently in hypothetical dilemmas compared to real-life scenarios. 

The Trolley Problem has become more relevant than ever with the advent of self-driving cars. For example, if someone ran into the road, should a driverless car swerve out of their way, causing a massive pile-up of multiple cars and potentially killing the diver and passenger, or actively decided to just carry on and hit the pedestrian in the road.


Of course, there is no “correct answer” to any of these dilemmas. However, it's undoubtedly a problem that researchers working on autonomous vehicles need to seriously confront, let alone lawyers involved in self-driving car crashes.

[H/T: New Scientist]


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