The proposed study is an observational investigation that aims to examine the impact of an unexpected and unusual event on prosociality within the Milan metro. The event is the simple presence, in the underground car, of a student wearing a Batman suit. The main objective is to assess whether or not the presence of the unusual event influences prosocial behaviour towards a student pretending to be pregnant. During the study, the student, equipped with a sponge prosthesis to simulate a pregnancy will board the underground. She will be asked not to interact with anyone, but to simply look at her phone. In the experimental condition, an individual dressed as Batman will enter the carriage (through a different door than the one used by the student). In the control condition, on the other hand, no one will show up in costume. In addition, the observer will try to gather information on the reason for this prosocial behaviour, noting down the answer given.

Inclusion Criteria:

• Being a passenger in the metro

Exclusion Criteria:

• Metro too crowded
• Seats available

-All metro passengers present at the time of the experiment are potential participants.

No identifying data will be stored.