Latane and Darley's Smoke-Filled Room Experiment

In 1968 Bibb Latane and John Darley published the smoke-filled room experiment, an early study of bystander behavior conducted in the aftermath of public concern over cases of witnessed emergencies that drew no intervention. Male undergraduate participants filled out a questionnaire in a waiting room either alone, in the company of two passive confederates instructed to notice the smoke and keep working without reacting, or in groups of three genuine participants, while smoke was released into the room through a wall vent to simulate a possible fire. When alone, about seventy-five percent of participants left the room to report the smoke within six minutes, most within about two minutes. When two nonreacting confederates were present, only about ten percent of genuine participants reported it in the same period, and groups of three genuine strangers were also slower and less likely to report than solitary participants. Latane and Darley attributed the effect to pluralistic ignorance, in which each person looks to others' outwardly calm reactions for cues about whether a situation is truly an emergency, and each person's apparent calm reassures everyone else that nothing is wrong. The study became a foundational demonstration underlying the broader bystander effect.