Lesson Plan

Psychology: The Bystander Effect


This 11-minute video introduces students to the theory of the bystander effect, including a discussion of the killing in 1964 of Kitty Genovese that spurred John Darley and Bibb Latane to design research that validated the theory. The video shows students how the bystander effect can be used to explain and possibly prevent situations in which bystanders fail to report violence they have witnessed online. Useful for any lesson that introduces the bystander effect or explores the connections between social psychology and social media, the video also presents recently discovered facts that have called into question the established narrative around Ms. Genovese’s death.

Content Advisory:

This video contains discussion of sexual assault, footage of streetfights and video captured after a police shooting.


  • How the killing of Kitty Genovese in 1964 gave rise to the concept of the bystander effect, and how newly uncovered facts have called into question the original narrative that surrounded the case.
  • How social psychologists used experimental research to test the theory of the bystander effect.
  • How the bystander effect can be used to explain why viewers of violent online videos don’t report what they witness, and how knowledge of the bystander effect might be used to develop solutions to this problem.
  • Psychology
  • Science
  • Cultural and Social Change
  • The Media
  • Social Media
  • 1960s America
  • The Postwar Era (1945-1980)
  • 21st Century
For Teachers

Introducing the Lesson

The failure of bystanders to report violence being livestreamed across social media is often blamed on the medium itself, but two social psychologists came up with a better explanation more than 50 years ago.

In the 1960s, John Darley and Bibb Latane were fascinated by the killing of Kitty Genovese in the Kew Gardens neighborhood of Queens. One night in March 1964, Ms. Genovese, 28, was sexually assaulted and stabbed to death while she was on her way home from work. There were reports that some 38 witnesses did nothing to stop the killing.

That, at least, was the front-page story in The New York Times two weeks after the crime. The apparent apathy and moral inaction of so many law-abiding citizens sent shock waves across the nation.

Darley and Latane wondered if there was more to the story. They conducted a series of experiments that led them to discover the bystander effect, the theory that the more witnesses to an event, the less likely it is that any one of them will intervene, in the expectation that someone else has already responded, or will.

Over the years, evidence has emerged that the Times story was innacurate. Two neighbors had, in fact, called the police. While dozens of people nearby heard Ms. Genovese’s screams, only a few saw the attack take place.

But the bystander effect has held up in other experiments and is still covered in textbooks, continuing to provide a critical insight into human behavior in the digital age.

Essential Questions

  • How did the Kitty Genovese case inspire Darley and Latane to develop the theory of the bystander effect?
  • How did Darley and Latane design their experiment? What did it reveal?
  • What newly uncovered facts have challenged the established narrative surrounding the Kitty Genovese case?
  • How did Facebook respond to digital bystanders making and watching violent videos on its platform?

Lesson Procedure

  • If a fellow student were livestreaming a fight in which several students were attacking another, and you saw that 100 people were watching the video, what would you do? Is there a difference between how we’d like to answer this question, and what the research seems to indicate about how we’re most likely to behave?
  • Why are people less likely to report an act of violence if they believe that many other people are witnessing the violence? What does that teach us about the psychology of responsibility and morality?
  • How can social media platforms be redesigned to work against the tendencies of the bystander effect?
  • Newly discovered facts have challenged some elements of the story about the night Kitty Genovese was killed. Should these facts cause us to question the validity of the experimental research that led to the creation of the bystander effect? What does this teach us about the research process?

Additional Resources

Transcript for "The Modern Bystander Effect"Retro Report
“What the Kitty Genovese Killing Can Teach Today’s Digital Bystanders”Retro Report
Audio Interview: "The 'Bystander Effect' in The Digital Age"WNYC

Describe how biological, psychological, and sociocultural factors influence behavior.

2.2 Describe the effects of others’ presence on individuals’ behavior.

Skill 1.B: Explain behavior in authentic context.

Questions? Tips? Concerns? Reach out to our Director of Education, David Olson: dolson@retroreport.com