A bystander will often intervene if another person is in need of help: this is known as bystander intervention. They will often do this for complete strangers, sometimes even at great personal risk.

However, people are less likely to assist if many other people are present. This propensity to passivity in the presence of others is called the bystander effect. The bystander effect (also known as bystander apathy) is a psychological phenomenon where persons are less likely to intervene in an emergency situation when others are present than when they are alone. ...

Factors that increase the odds of helping someone

• The victim is in some way similar to one's self
• Having just observed someone else being helpful
• Not being in a hurry
• Being in a small town or rural area
• The victim appears to need and deserve help

See also

• First aid
• Good Samaritan
• Altruism