Kelly McSweeney

Aug 26th 2020

What Is the Bystander Effect?


If you see someone in distress, will you help them? We all like to consider ourselves to be good people, but when we’re caught in the moment, we freeze. What is the bystander effect? For more than 50 years, psychologists have observed this phenomenon again and again in experiments and in real life. The research overwhelmingly shows the more people that are present when there’s an emergency, the less likely they are to help.

What Is the Bystander Effect?

Scientific studies have shown that in one-on-one situations, people will help each other out. However, when there are more witnesses, people are less likely to help.

Research suggests that this seemingly cruel behavior is part of human nature. In fact, the tendency toward group apathy may be wired into our brains. According to the Association for Psychological Science (APS), neuroscientists have observed the following brain response in bystander effect experiments:

  • When bystanders observed someone who was hurt or in danger, it activated their premotor cortex, which should have prepared them to help. But the presence of many bystanders also increased their personal distress. This triggers the “fight or flight” survival instinct, which can override their feelings of sympathy for the victim and prevent bystanders from helping out.

  • A higher number of bystanders is associated with decreased activity in the postcentral gyrus and the medial prefrontal cortex, the areas of the brain that are associated with helping responses.

  • Participants in one study watched a video in which an old woman collapsed. When there were more witnesses, there was decreased activity in the part of the brain that directs “prosocial behavior,” the medial prefrontal cortex.

What Causes the Bystander Effect?

Psychologists started studying the bystander effect after a woman named Kitty Genovese was murdered in front of a crowd in 1964, according to After this incident, John Darley and Bibb Latané conducted several experiments at New York University to find out why a crowd of seemingly decent people didn’t help. In one study, they asked participants to fill out a survey. While they were completing the survey, dark smoke started to enter the room. When participants were alone when this happened, 75% of them reported the smoke. If two other people were in the room, only 38% reported the smoke. The same researchers conducted additional experiments in which 70% of people helped a woman in distress when they were the only witness, but only 40% helped when there were additional bystanders. Since then, many additional studies have confirmed the bystander effect is real.

Several psychological factors are involved in what causes the bystander effect, according to and APS. Diffusion of responsibility is the concept that when more people are around, we assume that someone else (perhaps with more expertise) will help. Deindividuation is the phenomenon in which large crowds create a sense of anonymity, which can increase antisocial behavior. Pluralistic ignorance describes the fact that when nobody is helping, you assume it isn’t an emergency. Furthermore, evaluation apprehension is the fear of being judged for doing something different from the crowd. When other witnesses don’t react to an emergency, it sends a social cue that help isn’t needed.

Implicit racial bias makes the bystander effect even worse. The Washington Post describes a study in which researchers analyzed millions of emergency calls. They found that Black patients were half as likely to receive help from bystanders before paramedics arrive.

How to Counteract the Bystander Effect

Is it possible to overcome this selfish behavior? One factor that may help, according to, is reputational cost. This term describes the fact that people are more likely to intervene if they think they’ll look bad if they don’t help. Experts suggest that if victims call out an individual for help, it increases the likelihood that bystanders will take action.

Some people are able to fight the bystander effect and become good Samaritans. According to Discover Magazine, psychologists use the term “moral rebels” to describe people who take action to help, even when the status quo is inaction. These rebels tend to have certain personality traits (high self-esteem, conviction in their values) and a level of authority or skill, such as doctors, nurses, soldiers and firefighters. The next time you’re a bystander, Discover suggests asking yourself this question: if you act, will it matter? Taking it one step further, ask yourself what will happen if you do nothing at all.