The problem of witnesses not stepping in to help a victim is known as the:

1. Being one of several onlookers changes what a person does. 2. Discussion of bullying highlights the problem of witnesses not intervening to help a victim. 3. That failure to intervene is the bystander effect. 4. The more witnesses there are, the less likely any one of them is to act. _Source: OpenStax Psychology 2e (CC BY 4.0), Ch 12 'Social Psychology', sections 12.1-12.5_