Chapter Summary How Does Group Membership Affect People? 12.1 People Favor Their Own Groups Social psychology is the study of how people influence others' thoughts, feelings, and actions. People readily identify ingroups, to which they belong, and outgroups, to which they do not belong. Ingroup and outgroup formation is affected by reciprocity (if you help me, I will help you) and transitivity (friends having the same opinions about other people). The outgroup homogeneity effect is the tendency to perceive outgroup members as stereotypically more similar than ingroup members are. People also tend to dehumanize members of outgroups. According to social identity theory, individual social identity is based on identification with an ingroup. Ingroup favoritism is pervasive and may reflect evolutionary pressure to protect the self and resources. The medial prefrontal cortex appears important for ingroup formation. 12.2 Groups Influence Individual Behavior Group decisions can become extreme (group polarization), and poor decisions may be made to preserve group harmony (groupthink). The presence of others can improve performance (social facilitation). Working in a group can result in decreased effort (social loafing) if group members think their individual efforts cannot be monitored. Loss of individuality and self-awareness (deindividuation) can occur in groups.
12.3 People Conform with Others Conformity occurs when people alter their behaviors or opinions to match the behaviors, opinions, or expectations of others. Conformity results from normative influence (the attempt to fit in with the group and avoid looking foolish) and informational influence (learning the correct way to respond by observing). People may reject social norms and not conform when group size is small or when the group includes at least one other dissenter. Conformity appears in groups of about four or more members and is particularly strong when the group demonstrates unanimity. Conformity likely results from a fear of social rejection. 12.4 You Be the Psychologist: Can Social Norms Marketing Reduce Binge Drinking? Social norms marketing tries to correct false beliefs about drinking behavior by giving factual normative comparisons for average students. Although some programs have been successful, social norms marketing can backfire by increasing consumption of alcohol by light drinkers. The most successful programs include social norms marketing with persuasive arguments about the hazards of excessive alcohol consumption. 12.5 People Obey Authority Figures Obedience occurs when people follow the orders of an authority. As demonstrated by Milgram's famous study, people may inflict harm on others if ordered to do so by an authority. Individuals who are concerned about others' perceptions of them are more likely to be obedient. Obedience decreases with greater distance from the authority.
When Do People Harm or Help Others? 12.6 Many Factors Can Influence Aggression Aggression is influenced by situational, biological, social, and cultural factors. Situational factors that lead to negative emotions -factors including social rejection, fear, heat, and pain- can influence aggression. High levels of the hormone testosterone have been associated with aggressive behavior. However, it is difficult to determine whether high testosterone levels motivate aggression or threatening encounters produce high testosterone levels. It