Final answer:
The bystander effect is a phenomenon where witnesses or bystanders do not help a victim or person in distress. It is influenced by diffusion of responsibility and is important to be aware of to ensure help is provided.
Step-by-step explanation:
The question is about the bystander effect, which falls under the subject of Social Studies. The bystander effect is a phenomenon where witnesses or bystanders do not volunteer to help a victim or person in distress. This is influenced by diffusion of responsibility, which is the tendency for no one in a group to help because the responsibility is spread throughout the group. Research has shown that people are less likely to help if they don't know the victim. It is important to be aware of the bystander effect and take measures to ensure that someone in need gets the help they require.