# Lecture 22: Social Psychology II: Group Behavior and Prejudice
## Introductory Psychology
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## Learning Objectives
By the end of this lecture, students will be able to:
1. Explain how the presence of others affects individual performance through social facilitation and social loafing
2. Describe group decision-making phenomena including groupthink and group polarization
3. Analyze obedience and compliance using classic studies by Milgram and others
4. Define prejudice, stereotyping, and discrimination and explain their origins
5. Describe strategies for reducing prejudice and promoting intergroup harmony
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## Lecture Content
### I. Social Facilitation and Social Loafing
Robert Zajonc's 1965 theory of social facilitation explains how the mere presence of others affects performance. Others' presence increases physiological arousal, which enhances the dominant response — the response most likely to occur in a given situation. For simple or well-practiced tasks, the dominant response is usually correct, so performance improves. For complex or novel tasks, the dominant response is often incorrect, so performance worsens. Cottrell's refinement, evaluation apprehension, suggests that arousal increases specifically because we expect to be judged, which explains why social facilitation effects are stronger with evaluative audiences.
Social loafing is the opposite phenomenon: individuals tend to exert less effort when working in a group than when working alone. The Ringelmann effect demonstrates that as group size increases, individual effort decreases. Latane and colleagues (1979) showed that participants clapped and shouted less loudly in groups than when alone. The causes include diffusion of responsibility, reduced identifiability of individual contributions, and a sense that one's effort is dispensable. Social loafing is reduced when individual contributions are made identifiable, when personal accountability is increased, when people work with valued groups, when groups are smaller, and when the task is important. Cross-cultural research reveals that social loafing is less common in collectivistic cultures.
### II. Group Decision Making
Group polarization is the tendency for group discussion to strengthen the dominant pre-existing attitudes of group members. If members initially lean toward a risky decision, discussion will push the group toward greater risk; if they initially lean toward caution, the group will become even more cautious. Two mechanisms drive this effect: exposure to novel persuasive arguments favoring the dominant position, and social comparison — the desire to be perceived favorably relative to group norms.
Groupthink, described by Irving Janis in 1972, is a mode of thinking that occurs in highly cohesive groups when the desire for unanimity overrides the realistic appraisal of alternatives. It is most likely when the group is highly cohesive, insulated from outside opinions, led by a directive leader, lacks systematic decision-making procedures, and faces high stress with little hope of finding a better solution than the leader's preferred one. Symptoms include the illusion of invulnerability, collective rationalization, belief in the group's inherent morality, stereotyping of outgroups, self-censorship, the illusion of unanimity, pressure on dissenters, and self-appointed "mindguards." Historical examples include the Bay of Pigs invasion and the Challenger space shuttle disaster. Groupthink can be prevented by encouraging open dissent, assigning a devil's advocate, seeking outside expert opinions, allowing anonymous feedback, and having the leader withhold their opinion until others have spoken.
Deindividuation is the loss of self-awareness and self-restraint that occurs in group situations promoting anonymity and arousal. Zimbardo demonstrated that anonymous participants delivered more intense shocks to others. Factors contributing to deindividuation include anonymity, large group size, arousal, and reduced personal responsibility. While often associated with antisocial behavior such as rioting or online trolling, deindividuation can also facilitate prosocial behavior in collective celebrations.
A multi-panel figure on group decision-making phenomena. Panel A: Group polarization — a number line from "Cautious" to "Risky" shows individual members' pre-discussion positions (dots) slightly favoring risk, and post-discussion positions shifted further toward the risky end, with arrows indicating the shift. Panel B: Groupthink — a flowchart beginning with "Antecedent conditions" (high cohesion, insulation, directive leader), leading to "Symptoms" (illusion of invulnerability, self-censorship, pressure on dissenters), leading to "Defective decision making" (incomplete survey of alternatives, failure to examine risks, poor information search), ending in "High probability of a bad outcome." Panel C: A table contrasting strategies that promote vs. prevent groupthink.
### III. Obedience and Compliance
Obedience involves changing behavior in response to a direct command from an authority figure. Stanley Milgram's 1963 obedience experiment is among the most famous and disturbing studies in psychology. Participants, assigned the role of "teacher," were instructed to administer escalating electric shocks (from 15V to 450V) to a "learner" (actually a confederate) for each wrong answer. Despite showing visible signs of extreme distress, 65% of participants obeyed all the way to the maximum 450V shock level.
Several factors influenced obedience rates. Obedience decreased when the learner was in the same room (proximity of the victim), when the experimenter gave orders by phone rather than in person (proximity of the authority), when the study was conducted outside the prestigious Yale University setting, when other "teachers" refused to continue (presence of defiant peers), and when participants were made to feel personally responsible. The study generated significant ethical controversy regarding deception, psychological distress, and informed consent, but its core finding remains powerful: ordinary people can commit harmful acts when placed under authority pressure. The lesson is not about the character of the participants but about the power of the situation.
Compliance techniques are strategies designed to get people to agree to requests. The foot-in-the-door technique starts with a small request and escalates to a larger one, exploiting commitment and consistency. The door-in-the-face technique begins with an unreasonably large request (expected to be refused) and then presents the actual, smaller request, leveraging the principle of reciprocal concessions. The low-ball technique secures initial agreement and then reveals hidden costs. The that's-not-all technique sweetens the deal before the person has decided. The norm of reciprocity — the deeply felt obligation to repay favors — underlies many of these strategies.
A visual summary of Milgram's obedience experiment. Panel A: An illustration of the experimental setup showing three figures — the experimenter in a lab coat, the teacher (participant) at a shock generator panel with voltage levels labeled from 15V ("Slight Shock") to 450V ("XXX"), and the learner (confederate) strapped to a chair in an adjacent room. Panel B: A bar graph showing the percentage of participants who obeyed to the maximum shock level across different experimental variations: baseline (65%), learner in same room (40%), touch proximity (30%), experimenter absent (21%), and peer defiance condition (10%). Panel C: A comparison table of compliance techniques — foot-in-the-door, door-in-the-face, and low-ball — each with a brief scenario illustration and the psychological principle underlying it.
### IV. Prejudice, Stereotypes, and Discrimination
Prejudice is a negative attitude toward a group and its individual members, encompassing negative emotional reactions such as hostility, disgust, and fear. It can be explicit (conscious and deliberate) or implicit (unconscious and automatic). A stereotype is a generalized belief or expectation about a group — a cognitive shortcut that simplifies social information processing. Stereotypes can be positive or negative, but even positive ones can be harmful. They are resistant to change because people tend to attend to confirming evidence and discount disconfirming evidence. Discrimination is unjustified negative behavior toward a group or its members, manifesting in hiring decisions, social exclusion, and hate crimes. Discrimination can occur even without conscious prejudice, as in institutional or structural forms.
Prejudice operates at several levels. Old-fashioned or overt prejudice involves explicit beliefs in group superiority. Modern or aversive racism, described by Gaertner and Dovidio, characterizes people who consciously endorse egalitarian values but harbor unconscious negative feelings; their discrimination surfaces in ambiguous situations where prejudicial behavior can be attributed to other causes. Implicit bias, measured by the Implicit Association Test, reveals that people can show automatic preferences even when they explicitly deny them.
### V. Origins of Prejudice
Henri Tajfel's social identity theory explains that people derive self-esteem from their group memberships. The ingroup is the group to which one belongs; the outgroup is any group to which one does not. Ingroup bias — the tendency to favor one's own group — is so powerful that it emerges even in the minimal group paradigm, where people are categorized on entirely arbitrary bases.
Social cognitive processes also contribute. Categorization — automatically sorting people into groups — simplifies processing but creates an "us versus them" mentality. The outgroup homogeneity effect leads people to perceive outgroup members as more similar to each other than ingroup members ("They're all alike"). Illusory correlations arise when people overestimate the association between distinctive groups and rare behaviors. The scapegoat theory, derived from the frustration-aggression hypothesis, proposes that frustrated people may displace their aggression onto convenient outgroup targets.
Realistic conflict theory, supported by Muzafer Sherif's Robbers Cave experiment (1954), holds that prejudice arises from competition between groups for limited resources. In that experiment, two groups of boys at summer camp developed intense hostility when placed in competition, but prejudice was dramatically reduced when the groups were required to cooperate toward superordinate goals that neither group could achieve alone.
Stereotype threat, demonstrated by Claude Steele, shows that awareness of a negative stereotype about one's group can impair performance. African American students performed worse on tests framed as diagnostic of intelligence, and women performed worse on math tests when gender stereotypes were made salient. The mechanism involves anxiety, increased cognitive load, and reduced working memory capacity. Stereotype threat can be reduced by reframing the test, emphasizing the malleability of intelligence, and encouraging self-affirmation.
A multi-panel figure on prejudice and intergroup relations. Panel A: Social identity theory — a Venn diagram showing an ingroup circle and an outgroup circle, with arrows illustrating ingroup favoritism (positive attributions toward ingroup) and outgroup derogation (negative attributions toward outgroup). Below, a scale shows self-esteem derived from social identity. Panel B: The Robbers Cave experiment shown as a three-phase timeline — Phase 1: group formation (Eagles and Rattlers develop cohesion), Phase 2: intergroup competition (hostility, name-calling, flag burning), Phase 3: superordinate goals (cooperating to fix the water supply and pull a stuck truck), leading to reduced prejudice. Panel C: Stereotype threat — a bar graph comparing test performance when a math test is described as "diagnostic of ability" (women score lower than men) vs. "not diagnostic" (no gender difference), with annotations explaining the mechanism.
### VI. Reducing Prejudice
Gordon Allport's contact hypothesis (1954) proposes that intergroup contact reduces prejudice, but only under specific conditions: equal status between groups, common goals, intergroup cooperation, and support from authorities and social norms. Mere contact without these conditions can actually increase prejudice. Elliot Aronson's jigsaw classroom is a cooperative learning technique in which each student holds one piece of information essential to the group's task, creating interdependence. It has been shown to reduce prejudice while improving academic performance and self-esteem among minority students.
Additional strategies for reducing prejudice include pursuing superordinate goals that require intergroup cooperation, recategorization (shifting group boundaries to create a common ingroup identity), perspective-taking (imagining oneself in an outgroup member's position), education about implicit bias and stereotype threat, and structured intergroup dialogue.
### VII. Aggression and Prosocial Behavior (Overview)
Aggression is physical or verbal behavior intended to harm another person. Hostile aggression is driven by anger with the goal of inflicting pain, while instrumental aggression is a calculated means to another end. Biological factors include genetics, testosterone, low serotonin levels (associated with impulsive aggression), and neural circuits involving the amygdala and prefrontal cortex. Psychological factors include the frustration-aggression hypothesis, social learning through modeling and media violence, and hostile attribution biases. Situational factors such as heat, crowding, provocation, and alcohol (which reduces inhibition) also contribute.
The bystander effect describes the finding that the more bystanders present at an emergency, the less likely any individual is to help. Research sparked by the Kitty Genovese case (1964) led Latane and Darley to develop a five-step decision model of bystander intervention: noticing the event, interpreting it as an emergency, assuming personal responsibility, knowing how to help, and deciding to act. Diffusion of responsibility — the assumption that someone else will intervene — is the primary mechanism. Helping is more likely when the person is alone, knows how to help, feels empathy, perceives personal responsibility, and identifies with the victim.
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