This version of the "trolley" thought experiment is explored in the book I mentioned in a previous post. It turns out people will not choose to steer a trolley of people needing organ replacements into a healthy potential organ donor. Thus, most people really aren't utilitarians, even if they claim to be. Unfortunately, one of the chemical processes in the brain reverses this attitude when someone prone to road rage spies a cyclist.

A typical response is that these sorts of mental games are silly, but how people answer these questions actually forms the basis of legal systems throughout the world.