So, a researcher did a (fake) real-life version of the Trolley problem, where they would threaten
mice with electric shocks.
In the lab were two cages with red plastic lids and mice inside, an electroshock machine, and a laptop that showed the 20-second timer. When the timer got to zero, the experiment was over. No shocks were ever administered to the animals, but the laptop recorded whether (and when) each participant had pressed the button. Participants would see, in the end, that the button had no effect—but at that point they’d already made their choice.
What was interesting to this experiment is that in the "real-life" situation, people were more likely to choose the utilitarian option and press the button.
About five-sixths of these subjects pressed the actual button, suggesting they were more inclined to make that choice in real life than their fellow subjects were in hypotheticals. Moreover, people’s responses to the 10 trolleyology dilemmas they were given at the start of the experiment—whether they imagined that they’d push the fat man off the bridge and all that—did not meaningfully predict their choices with live mice. Those who had seemed to be more focused on the greater good in the hypotheticals did seem to press the real-life button more quickly, though, and they described themselves as being more comfortable with their decision afterward.
In my opinion, the real-world experiment fails to capture the nuance of the original problem. There is a big difference between choosing whether or not to be responsible for the death of one or more people and giving a little shock to some rodents. I definitely fall more into the "pulling the lever is murder" camp, but I'd probably press the button on the rodents, because the harm you are doing is minimal.
The actual experiment does give some insight into how people may change what they would do in a real situation versus just a thought experiment, but I don't think you can draw any conclusions as to how someone would react in a real life-or-death trolley situation.
Anyway, the purpose of the trolley problem is really to help people examine their own ethical thought processes. Why would you be willing to flip the switch but not push the fat man? What are the different moral implications for all of the variations? More importantly, who keeps tying all these people to the trolley tracks?