During times of emergency in a public place, people act differently when there are several people than when there are just a few. If you had fallen and badly injured yourself, the surrounding masses of people are less likely to help you than if just one or two people were present. This is called the bystander effect.

Which type of psychologist would be most interested in studying why people in crowds are less likely to help a bloody, injured person needing help?

forensic psychologist
organizational psychologist
social psychologist
counseling psychologist