This story appeared in the June 2020 issue as "Action!" Subscribe to Discover magazine for more stories like this.
On April 9, 2017, three security officers from the Chicago Department of Aviation forcibly removed David Dao from an overbooked United Airlines flight. Dao, a 69-year-old doctor, was dragged down the plane’s aisle after he refused to give up his seat. In the process, his head hit an armrest and he was knocked unconscious.
The passengers clearly recognized what was occurring: Many took out their phones and filmed the scene and later expressed their outrage loudly on social media. Yet at the time, only one woman said anything, yelling out, “What are you doing?” No one confronted the officers or intervened to prevent what was clearly inappropriate behavior.
At some level, this is hardly surprising. Numerous studies have shown that we are less likely to intervene when other people are present. We assume that others will do something, and we don’t have to. Psychologists call this phenomenon the bystander effect.
