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The Hidden Danger of Crowds: Why Bystanders Fail to Act

Imagine this: You’re walking down a busy street when you encounter something disturbing. A man accosts a woman and begins shouting at her. When she tells him to leave her alone, he starts violently threatening her. A large crowd gathers, wondering what the commotion is about. But nobody steps forward to help.

What about you? Would you be the hero who breaks from the crowd to protect the victim? Many of us believe we’d step in to help. But in reality, very few of us would. And it’s not because we’re bad people. It’s because of something called the bystander effect.

What is the Bystander Effect?

The concept of the bystander effect comes from a classic 1968 study. Subjects were asked to have a personal conversation over an intercom system with a group of strangers, who were all secretly actors.¹ Suddenly, one of the strangers began calling for help, saying he was having a seizure.

Researchers noticed something interesting: subjects’ responses depended on group size.² When subjects thought that they alone could hear the victim’s calls for help, they reported the emergency to the researchers.³ But among subjects in groups with 4 other strangers, only 62% responded to the emergency.

In other words, your willingness to take action in a crisis situation depends on how many other witnesses there are.

What Causes Witness Inaction?

In general, the bigger the crowd, the less likely you are to intervene.⁵ But why does this occur? Social psychologists identify 3 main factors that contribute to the bystander effect.

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1. Diffusion of Responsibility

The larger the size of the crowd, the less you feel personally responsible for taking action.⁷ When you’re surrounded by a lot of other people, it’s easy to convince yourself that it’s not your job to get involved.

You might tell yourself, Even if I don’t step in to help, I’m no more to blame than any of these other people who aren’t helping. Or you might just assume that someone else will take care of it.

In contrast, if you’re the only witness, you feel directly responsible for intervening—because if you fail to act, there’s no one else to blame.

A modern example of this phenomenon? Cyberbullying. According to researchers, Internet users who witness cyberbullying are less likely to intervene if their identities are kept anonymous.⁸ When there’s no real identity attached to your online persona, you feel even less accountable for your own action—or inaction.

2. Evaluation Apprehension

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Have you ever felt unable to speak up because you fear that others will judge you? If so, you’ve experienced evaluation apprehension.⁹ Many bystanders worry that, by taking action, they will make the situation worse or somehow embarrass themselves.

It’s natural to be concerned about what others think. But in a large group of strangers, this fear can become strong enough to prevent you from stepping in to help.

3. Pluralistic Ignorance

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Some situations are clearly emergencies: car crashes, natural disasters, violent crimes. But other times, a situation is more ambiguous. Is that woman stumbling around because she’s seriously ill, or is she just drunk?¹⁰ Are those men just arguing, or are they about to become violent?

In unclear social situations, we look for information from the people around us. We make conclusions about the situation based on how they are behaving.¹¹ So if nobody else in the crowd is taking action, we’ll assume that it isn’t really an emergency.¹²

Being an Active Bystander

The big takeaway is that the attitudes, behaviors, and even the mere presence of other people affects how—and if—we take action. But if other people affect our individual responses, that means we also affect others’ responses.

One key way to combat the bystander effect is learning to be an active bystander. Many universities and workplaces incorporate bystander training into sexual assault and violence prevention efforts. Programs like Bringing In the Bystander and TakeCARE show participants how to recognize when intervention is necessary, and teach them how to confidently take action even when others don’t.¹³ Studies of these programs have found that they increase intent and willingness to serve as active bystanders.¹⁴

To be an active bystander, you need a sense of self-efficacy—confidence in your own knowledge and ability to intervene effectively.¹⁵ Like any other skill, building self-efficacy takes lots of practice.

Toa Heftiba / Unsplash

So don’t wait until you encounter a huge crisis. Start by taking smaller actions in your daily life. Your coworker made a racist comment to a colleague? Don’t let it go: point it out, or bring it up to a manager. You witness sexual harassment on the train? Don’t pretend not to see: do something.


It can be nerve-wracking to step in like this, especially in a public setting. But by being an active bystander, you’re setting an example to the people around you. You’re reminding them that injustice should be confronted, not tolerated. Mistreatment should be addressed, not ignored. And many times, it only takes one person to take action before others soon follow.



  1. Darley, J. M., & Latane, B. (1968). Bystander Intervention in Emergencies: Diffusion of Responsibility. Journal of Personality and Social Psychology, 8(4), 377-383. doi:10.1037/h0025589

  2. Ibid.

  3. Ibid.

  4. Ibid.

  5. Fischer, P., Jrueger, J. I., Greitemeyer, T., Vogrincic, C., Kastenmüller, A., Frey, D., . . . Kainbacher, M. (2011). The Bystander-Effect: A Meta-Analytic Review on Bystander Intervention in Dangerous and Non-Dangerous Emergencies. Psychological Bulletin, 137(4), 517-537. doi:10.1037/a0023304

  6. Hortensius, R., & de Gelder, B. (2018). From Empathy to Apathy: The Bystander Effect Revisited. Current Directions in Psychological Science, 27(4), 249-256. doi:10.1177/0963721417749653

  7. Ibid.

  8. You, L., & Lee, Y. (2019). The Bystander Effect in Cyberbullying on Social Network Sites: Anonymity, Group Size, and Intervention Intentions. Telematics and Informatics, 45. doi:10.1016/j.tele.2019.101284

  9. Hortensius & de Gelder (2018)

  10. Rendsvig, R. K. (2014). Pluralistic Ignorance in the Bystander Effect: Informational Dynamics of Unresponsive Witnesses in Situations Calling for Intervention. Synthese, 191, 2471-2498. doi:10.1007/s11229-014-0435-0

  11. Ibid.

  12. Ibid.

  13. Mujal, G. N., Taylor, M. E., Fry, J. L., Gochez-Kerr, T. H., & Weaver, N. L. (2019). A Systematic Review of Bystander Interventions for the Prevention of Sexual Violence. Trauma, Violence, & Abuse. doi:10.1177/1524838019849587

  14. Ibid.

  15. Kettrey, H. H., & Marx, R. A. (2020). Effects of Bystander Sexual Assault Prevention Programs on Promoting Intervention Skills and Combatting the Bystander Effect: A Systematic Review and Meta-Analysis. Journal of Experimental Criminology. doi:10.1007/s11292-020-09417-y


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