Bystander effect: everyone waits, no one helps
About this app
Two classic experiments by Latané and Darley in 3D: smoke enters a waiting room where a person sits alone, with two passive confederates or with two real participants; a seizure over the intercom where all other voices come from a tape. Curves with the original results (75 %, 10 %, 38 % instead of an expected 98 %) and a model showing when more bystanders even mean less help.
With explain mode: an AI tutor walks you through the app, points out what matters in the scene and answers your questions.
The bystander effect
The bystander effect describes how people intervene less often and later in an emergency when they believe others are watching. In 1968 Latané and Darley named two reasons: diffusion of responsibility, because each person feels less responsible, and pluralistic ignorance, because unsure people look at the others and take their calm as a sign that nothing is wrong. In the smoke experiment 75 % reported the smoke when alone, but only 1 in 10 with two passive confederates. With three real participants someone reported in only 38 % of groups, where over 98 % would have been expected.
What the app shows
A 3D waiting room: smoke comes through a vent while a person fills in a questionnaire, alone, with two confederates or with two other real participants. The figures show a typical run: walking to the vent and reporting it, or looking at the others and staying seated. In the second experiment each person sits alone in a cubicle and hears a seizure over the intercom; the debriefing reveals that all other voices came from a tape. Alongside run the curves with the values from the original papers and a dashed expectation for independent people.
Try it yourself
Switch between conditions and play the six minutes. In the model you set how many people could help and how strong the inhibition is: one person helps with p(n) = p₁ · n^(−h), at least one with 1 − (1 − p(n))^n. Once the inhibition is above 1, every extra person even lowers the chance that anyone helps at all. A button fits the model to the data. The info panel puts later findings in context, including a meta-analysis and CCTV recordings of real conflicts.
Frequently asked questions
- What is the bystander effect?
- The bystander effect is the finding that individuals help less often or later in emergencies when other bystanders are present or believed to be present. It is explained by diffusion of responsibility and pluralistic ignorance. It became known through the experiments of Latané and Darley in 1968.
- What happened in Latané and Darley’s smoke experiment?
- Students filled in a questionnaire in a waiting room while smoke came through a wall vent. Alone, 75 % reported the smoke, half of them within two minutes. With two confederates who kept writing indifferently, only 1 in 10 reported it, and of eight groups of three real participants only 3 did.
- Is the story of Kitty Genovese and the 38 witnesses true?
- Not in the way it was told for decades. A 1964 newspaper report spoke of 38 idle witnesses to a murder in New York. Later reviews of the records found far fewer eyewitnesses, many had only heard something, and the police were called.
- What can I try in this app?
- You play the smoke and the seizure experiment in three conditions, see the original results as curves and reveal who was a confederate. In the model you change the number of potential helpers and the inhibition and see when a larger group even helps less often.
Subject: Psychology
More from Psychology
- Asch lines: the majority is wrong on purpose
- The experimenter in the experiment
- The one-dollar lie
- Forgetting and review
- Perception lab
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