How do social psychologists differ from those who rely on common sense or folk wisdom in answering questions about human nature? social psychologists?

Social science or scientist do the study in all aspects of society. a social scientist experiments on to know the relationship of humans with each other and their behavior. This is the study that provides different insights about the different fields in society such as individuality, groups, and institution.

A social scientist collects the data, analyze the data and take record historically, etc. Social scientists focused on the study of physical, social-cultural and other aspects of society. They even analyze the custom and tradition in the society that is related to the cultural value.  

you should think about the answers you give and expect the same form your questions.