• social psychology: the study of the causes and consequences of sociality
• aggression: is behavior whoses purpose is to harm another
• cooperation: behavior by two or more individuals that lends to mutual benefit
• group: collection of people who have something in common that distinguishes them from others
• prejudice: positive or negative evaluation of another person based solely on their group membership
• common knowledge effect: tendency for group discussions to focus on information that all members share
• group polarization: tendency for groups to make decisions in order to achieve it
• groupthink: tendency for groups to reach consensus in order to facilitate interpersonal harmony
• deindividuation: occurs when immersion in a group causes people to become less concerned with their personal values
• diffusion of responsibility: refers to the tendency for individuals to feel diminished responsibility for their actions when they are surrounded by others who are acting the same way
• bystander intervention: act of helping strangers in an emergency situation
• altruism: intentional behavior that benefits another at a cost to oneself
• kin selection: the process by which evolution selects for individuals who cooperate with their relatives
• reciprocal altruism: behavior that benefits another with the expectation that those benefits will be returned in the future
• mere-exposure effect: tendency for liking to increase with the frequency of exposure
• social influence: ability to change or direct another person's behavior
• norms: the unwritten rules that govern behavior...customary standards for behavior that are wiedly shared by members of a culture
• normative influence: occurs when another person's behavior provides information about what is appropriate
• norm of reciprocity: unwritten rule that people should benefit those who have benefited them
• conformity: the tendency to do what others do simply because others are doing it