People React To The Trolley Problem The Same Way Across The Planet, Study Suggests


Dr. Katie Spalding

Katie has a PhD in maths, specializing in the intersection of dynamical systems and number theory.

Freelance Writer


POV: you have been captured by an experimental philosopher. Image: George Wirt/Shutterstock

When it comes to psychology, culture has a lot to answer for. Like: which is the odd one out from the choice of a monkey, a panda, and a banana? The answer isn’t as cut-and-dry as you might think. Or consider dhat syndrome, a psychiatric disorder that convinces men in South East Asia (and apparently nowhere else) that they are becoming impotent and leaking semen.

The more you explore the effect culture can have on the way humans think, the more you may think that maybe there’s no universal human experience at all. However, a new paper published in the journal Nature Human Behaviour suggests that we might all be a bit more alike than we realize – at least when it comes to life and death situations.


The study centered on that favorite of thought experimenters and meme artists the world over, the “Trolley Problem.”

First posited in 1967 by philosopher Phillipa Foot, the problem goes as follows: suppose you’re driving a trolley with cut brakes. On the track are five people, who will be killed if you don’t redirect the trolley onto the other track. But on the other track is one person, who will be killed if you do redirect the trolley. What do you do?

“[We] examined these moral dilemmas across 45 countries,” wrote Carlota Batres, one of the co-authors of the study, in an article for Psychology Today. “People were less likely to judge sacrificing one person to save more people as morally acceptable when they had to use their personal force to kill the person.”

“This effect was found across countries, providing evidence that the personal force effect is influenced by basic cognitive and emotional processes that are universal for humans,” she added.


Foot originally posed the dilemma as an ethics conundrum, but in recent years it’s found new life in the field of psychology – asking not what a person ought to do, but what they actually would do. It’s even been tested in real life (or at least as close as you can get without ending up in prison) which is how we know you’re probably more likely to swerve for a kitten than a criminal.

However, almost all of that research was undertaken on one type of person: WEIRD people. That’s not an insult – it’s a real demographic term, standing for Western, Educated, Industrialized, Rich, and Democratic. In other words, the results we’ve got so far are interesting, but not necessarily universal – would they hold up in collectivist societies like those found in East Asia, for example, or in a dramatically younger population like the ones in East Africa?

To examine these kinds of questions, the researchers sent out surveys to over 41,000 people in 45 countries, asking them to consider one of six variations of the trolley problem. Participants were also asked to think through what the team called the “speedboat problem” – a sort of inverse trolley problem, where the dilemma is which of two groups should be saved rather than killed.

“These findings are important since the dilemma between utilitarian and deontological principles plays a prominent role in law and policy-making decisions, ranging from health budget allocations to the protocols of self-driving cars,” wrote Batres. “The way people perceive or act on these moral rules can influence the policies that are accepted, and therefore, these findings provide necessary insights into which factors contribute to moral perceptions.”


But exactly how much should we take from this study? Although the team found that people everywhere seem to have the same reaction to the trolley problem – judging that an action taken that kills one person is wrong, even if it saves others – the effect isn’t overwhelming outside of Western countries. In the speedboat problem, things were even less consistent.

And then there are the study limitations. Despite the massive initial data pool, over four-fifths of participants had to be disqualified, which the study notes “might have resulted in unintended selection biases” such as the loss of more educated participants.

Many of those who did get through to the final study were younger, with more access to the internet and therefore Western culture, which may have influenced the outcome. While care was taken to present the surveys in native languages, the researchers noted that not all questions may have translated perfectly across cultures – the team thinks that may be what caused the weird (but not WEIRD) result in the speedboat problem – and the scale used to rate the ethics of the survey’s hypotheticals may be overly simplistic to cope with the full range of human moral wrangling.

“This research has a number of limitations that future work will need to address,” the authors explain. “Although we call the personal force effect ‘universal’, it is only universal to the cultures we tested.”


“Future work, especially replication work, should take caution when applying stringent exclusion criteria as it may be entirely unnecessary and even hurt the discovery of new effects,” they suggest.

So, while it looks like most people are united in not wanting to murder others (even if it’s for the greater good), it looks like it’s still an open question as to just how universal that moral judgement is. Perhaps the only thing we can say for sure – at least, for now – is that humans, when faced with life or death, are anything but predictable.


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