When an event occurs in which many people determine a need for exists and it is an emergency, according to the bystander intervention decision-making model what factor is most likely to determine whether anyone steps in to ?

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The bystander effect occurs when the presence of others discourages an individual from intervening in an emergency situation. The greater the number of bystanders, the less likely it is for any one of them to provide help to a person in distress. People are more likely to take action in a crisis when there are few or no other witnesses present.  

Social psychologists Bibb Latané and John Darley popularized the concept of the bystander effect following the infamous murder of Kitty Genovese in New York City in 1964. The 28-year-old woman was stabbed to death outside her apartment, neighbors failed to step in to assist or call the police. Latané and Darley attributed the bystander effect to the perceived diffusion of responsibility (onlookers are less likely to intervene if there are other witnesses who seem likely to do so) and social influence (individuals monitor the behavior of those around them to determine how to act).

bystander effect or bystander apathy

Explanation:

bystander effect, or bystander apathy, is a social psychological claim that individuals are less likely to offer help to a victim when other people are present; the greater the number of bystanders, the less likely it is that one of them will help.

Several factors contribute to the bystander effect, including ambiguity, group cohesiveness, and diffusion of responsibility that reinforces mutual denial of a situation's severity.

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the scientific method.