Normally we say that “Santa is watching” when we want to encourage good behavior. But it turns out it may be more effective to warn that “Batman is watching” instead!

After making a guy dressed as Batman stand around in a subway car, a team of researchers found that the behavior of people around him suddenly improved the moment he showed up. No longer was everyone completely self-involved; with the presence of a superhero, commuters started helping each other more than they would’ve without him around.

The findings of the unorthodox study, published in the journal npj Mental Health Research, demonstrate the power of introducing something offbeat into social situations to jolt people out of the mental autopilot they slip into to navigate the drudgery of everyday life.

Batman showing up is just one — albeit striking — way of promoting what’s called “prosocial behavior,” or the act of helping others around you, via introducing an unexpected event, the researchers write.

In a series of experiments, the researchers had a woman who visibly appeared pregnant enter a busy train, and observed how often people offered to give up their seats. They then repeated this scenario with a crucial change: when the pregnant woman entered the train from one door, a man dressed as Batman entered from another.

In all, the team observed 138 passengers, and the results were clear-cut. Over 67 percent of passengers offered their seats when Batman was present, compared to just over 37 percent when Batman wasn’t there. Most, in both cases, were women: 68 percent with Batman there, and 65 without him.

But the most strange detail? 44 percent of the people who offered their seats later reported that they didn’t even notice Batman was there in the first place, suggesting that they don’t need to be consciously aware of the offbeat event itself to, in colloquial terms, pick up the prosocial vibes.

This revolutionary sociological research could one day help to create strategies to promote altruistic behaviors in daily life, from public art installations to innovative social campaigns. So don't be surprised if you see Batman standing watch!