- Prosocial behavior is essential to social life, but spontaneous environmental triggers for it are underexplored; this study tests if an unexpected event (a person dressed as Batman) can increase prosocial behavior.
- A quasi-experimental field study on the Milan metro (138 rides) found passengers were significantly more likely to offer their seat to a pregnant woman when Batman was present (67.21%) than in the control condition (37.66%), with an odds ratio of 3.393.
- The presence of Batman significantly influenced prosocial behavior (p < 0.001), explaining 11.2% of variance, and most helpers were women in both conditions.
- Interestingly, 43.75% of those who offered their seat in the Batman condition reported not seeing Batman, suggesting the effect may not require conscious awareness.