A study investigated the psychology of 'bystander compliance'—specifically, whether individuals can be socially pressured to pocket lost property rather than handing it in to authorities.

Confederates were used to encourage unsuspecting members of the public to keep a lost wallet containing a small sum of cash and a mock ID, which had been 'accidentally' dropped on a commuter train carriage.

There were three conditions in the study:

• Two confederates sat next to an unknown passenger and actively pressured them to keep the wallet and pocket the cash.
• One confederate first engaged an unknown passenger in friendly conversation for 15 minutes to establish a warm rapport, before dropping the wallet and then encouraging them to keep it.
• One confederate dropped the wallet near an unknown passenger and briefly suggested they keep it, without any prior social interaction.