Difficulty: Intermediate | Prerequisites: Familiarity with basic social psychology (attitudes, attribution), plus the conflict and relationships material. Understanding of the frustration-aggression link helps with the aggression section.
Aggression and stress are two of the most consequential topics in social psychology, bridging biological processes (testosterone, cortisol, frontal asymmetry) with social and situational influences (modelling, poverty, social exclusion, weapons effects). The aggression lectures cover the distinction between instrumental and hostile aggression, the role of testosterone and anger, situational triggers, and evidence-based strategies for reducing aggressive behaviour. The stress lectures examine how the body responds to stressors (Selye's General Adaptation Syndrome, cortisol), why social evaluative threats and uncontrollable situations produce the strongest stress responses (Dickerson and Kemeny), and how people cope. Both topics connect to relationship conflict and prosocial behaviour covered earlier in the course.
Aggression is behaviour intended to harm and comes in two forms: instrumental (goal-directed) and hostile (impulsive, anger-driven). Testosterone's role is nuanced and largely correlational in humans; situational factors (weapons, heat, social exclusion, poverty) are strong predictors. Catharsis does not work. Stress is a psychobiological response involving cortisol, autonomic arousal and immune changes; social evaluative threats and uncontrollable situations produce the largest cortisol spikes. Coping can be problem-focused (changing the source) or emotion-focused (managing the response), and humans are broadly resilient.
Aggression
Behaviour intended to harm another individual. Ranges from mild (passive-aggressive) to extreme (overt violence). Think of it as any deliberate act aimed at causing harm.
Hostility
An anger-infused attitude that predisposes someone towards aggression (e.g. hate, prejudice). It can exist as a cognition without being acted upon.
Instrumental aggression
Aggression performed to achieve a goal: gaining resources, self-defence, winning a competition, attracting attention. In simple terms, aggression as a tool.
Hostile (emotional) aggression
Impulsive aggression driven by anger, with the primary goal of hurting someone. Linked to poor impulse control and often carries costs for the aggressor.
Frustration-aggression hypothesis
The theory that frustration (being blocked from a goal) increases the likelihood of aggression, which can be displaced onto unrelated targets (scapegoating).
Catharsis
The idea that venting anger (through physical activity, watching violence, etc.) reduces aggressive urges. The research shows this is wrong: venting increases hostility.
Stress
A complex psychobiological response to a stressor, involving endocrine responses (cortisol), autonomic arousal (heart rate, vascular changes) and immune activity (pro-inflammatory cytokines).
Cortisol
The primary stress hormone. Adaptive in short bursts but maladaptive when chronic: it depletes energy, promotes abdominal fat, depresses mood and suppresses immune function.
General Adaptation Syndrome (GAS) (Selye)
A three-stage model of the stress response: alarm (immediate sympathetic activation), resistance (sustained arousal and energy deployment), exhaustion (resource depletion and vulnerability to disease).
Social evaluative threat
A stressor that occurs when aspects of the self could be negatively judged by others, such as being evaluated, recorded or outperformed.
PTSD (post-traumatic stress disorder)
A condition involving enduring physical and psychological symptoms following a stressful event. Effects may be transmitted intergenerationally.
Problem-focused coping
Dealing with the source of the stress directly (e.g. confronting a harasser). Most effective when the situation is controllable.
Emotion-focused coping
Managing the emotional response to stress rather than the stressor itself (e.g. exercise, seeking support). More effective when the situation is not controllable.
Aggression: behaviour intended to harm another individual, ranging from passive-aggressive to violent
Hostility: an anger-infused attitude (hate, prejudice) that may exist as a cognition without being acted upon
Instrumental aggression: done to gain something (resources, attention, self-defence, military objectives)
Hostile/emotional aggression: impulsive, done to hurt someone, linked to poor impulse control
Anger is a response to goal-blocking and is associated with both hostile and instrumental aggression. Frustration leads to anger, which leads to aggression.
Anger and approach motivation (Harmon-Jones and Sigelman): Greater left-frontal brain activity, associated with approach motivation, predicted more aggression (longer noise blasts in the Competitive Reaction Time Game) after participants received insulting feedback.
Nature: evolutionary instincts, biological and genetic processes
Nurture: role models, exposure to violence, modelling (Bandura)
The interaction of nature and nurture is key
The link between testosterone and aggression remains unclear in humans.
In animals (challenge hypothesis): Testosterone rises during breeding season and when dominance is challenged. In monogamous species, testosterone drops when males care for offspring. In chimps, testosterone rises around females in oestrus and increases aggressive competition among dominant males. Muller and Wrangham concluded that testosterone normally supports reproductive behaviour and only enhances aggression in "challenge situations."
In humans: Testosterone rises at puberty but does not produce a corresponding increase in aggression. Human testosterone levels are higher during sexual arousal, competition and dominant behaviour, and lower in paternal men. Research is almost entirely correlational. Hermans et al. administered exogenous testosterone to women and found enhanced neural responses to social threats (attention and threat processing), but this does not directly demonstrate a link to aggressive behaviour.
Modelling (Bandura): violent media and family violence teach aggressive behaviour
Poverty and inequality (Daly, Wilson and Vasdey): greater income inequality correlates with more homicides and violence. Mechanisms include frustration leading to displaced aggression (scapegoating) and competition for resources.
Social exclusion (Twenge et al.): excluded participants gave louder and longer noise bursts, even to people unrelated to the original exclusion. Loneliness is a strong predictor of health problems.
Weapons effect: men in the presence of guns were more aggressive. Being primed with weapons lowers the threshold for what we label aggression. Handling a gun (vs. a toy) also increased testosterone and subsequent aggressive behaviour.
Situational cues: black uniforms are associated with more penalties in sport. Heat increases discomfort and aggression.
Frustration (goal-blocking) engages aggression, which can be displaced onto others (scapegoating). This led to the idea of catharsis (venting anger through violent media or physical outlets), but research shows that catharsis increases aggression rather than reducing it.
Catharsis: venting anger (punching bags, watching violent media) increases hostility rather than reducing it
Aggressive fantasy: there is a positive link between fantasising about aggression and aggressive behaviour, though low exposure to real violence weakens this connection
Better role models: exposure to non-aggressive models reduces aggression
Empathy: taking the other person's perspective
Apology: diffusing anger through sincere apology
Self-regulation: the ability to control aggressive impulses. Humans are not naturally skilled at this, but failure to self-regulate carries serious social consequences (exclusion, reputational harm)
Positive mood: some evidence that humour diffuses aggression, though this may work through distraction. Approach-related positive emotions (excitement, enthusiasm) may increase anger, while affiliative goals may reduce aggression.
Males tend towards more direct, physical aggression
Females tend towards indirect aggression: gossiping, social exclusion, shunning
Paluck et al. found that highly connected students (not necessarily the most liked, but the most well known) were the most effective at spreading new social norms about conflict.
A complex psychobiological response to a stressor involving three systems:
Endocrine response (cortisol release)
Autonomic arousal (heart rate, vascular changes)
Immune activity (pro-inflammatory cytokines)
Short-term cortisol is adaptive. When stress becomes chronic, cortisol turns maladaptive: it depletes energy, promotes abdominal fat storage, depresses mood and suppresses immune function.
Three stages:
Alarm: immediate reaction to a threat, sympathetic nervous system activation
Resistance: sustained arousal and immune activity, continued energy deployment
Exhaustion: results from chronic stress, body's resources are depleted, vulnerability to disease increases
Selye's key insight: the stress response is a critical psychophysiological response for normal behaviour, but it becomes maladaptive when prolonged.
Stress responses evolved for short-term threats (predators, fights). Humans are unique in their ability to generate chronic stress through worry, rumination and anticipation. Our bodies are not adapted to handle long-term stressors.
Self-report: perceived stress scales, life event checklists
Biological measures: cortisol levels, immune system markers
Objective indicators: degree of exposure to stressors, proximity to traumatic events
Stress is strongly linked to social relationships and situations. Social stressors (public speaking, being evaluated) are among the most potent activators of the physiological stress response.
Occurs when aspects of the self are, or could be, judged by others. Conditions that produce it include being recorded or filmed during a task, performing before an evaluating audience, and being outperformed by a confederate.
Occurs when the person's responses cannot affect outcomes. Conditions include impossible tasks, time constraints, false feedback of poor performance, criticism from the experimenter, and inescapable loud noise.
A widely used laboratory stressor: participants prepare a speech in a short time, deliver it before an unsmiling panel, then count backwards from a large number. Cortisol is measured before, after and at a follow-up interval.
Key findings from a meta-analysis of cortisol response studies:
Emotion induction and noise exposure alone did not produce significant cortisol responses
Uncontrollable, social evaluative conditions produced the largest cortisol responses and the slowest recovery
Only tasks combining social evaluative threat with uncontrollability resulted in cortisol levels that failed to return to baseline within one hour after the stressor ended
The combination of being judged and having no control over the outcome is the most potent stressor for cortisol activation
Rejection from social groups is traumatic, associated with lower self-esteem, depression, greater physical illness risk and reduced immune function.
Sensitivity to social rejection is associated with lower baseline cortisol (thought to represent a "giving up" response) and reduced immune cell production. Animal studies confirm this: isolated animals are more likely to develop infections, while cage mates enhance resilience.
Reactions to terrorism, war, natural disaster and other traumatic events include loss of a sense of control, depression, physical illness and PTSD. PTSD involves enduring physical and psychological symptoms after a stressful event, and its effects may be passed to the next generation.
Being a member of a stigmatised social group is stressful. Stigma often functions as a chronic stressor with implications for both mental and physical health. Black Americans report being discriminated against more often than white Americans, and the experience of discrimination varies by context.
Problem-focused coping: addressing the source of the stress directly. More effective when the situation is controllable (e.g. talking to your boss about harassment).
Emotion-focused coping: managing the stress response itself rather than the stressor. More effective when the situation is not controllable (e.g. exercise after a loss).
Proactive coping: building defences in advance (social support, religion)
Planning/active coping: developing a strategy for what to do
Positive reinterpretation: finding something good in the situation
Acceptance: learning to live with it
Seeking social support: asking people with similar experiences for guidance
Venting emotions: letting feelings out
Mental disengagement: turning to work or other distractions
Denial: pretending it did not happen
The good news: humans are extremely resilient. Most people recover from stressful experiences and return to normal functioning over time.
"Testosterone causes aggression in humans." The evidence in humans is almost entirely correlational. Testosterone is associated with dominance behaviour, but dominance is expressed in many ways that are not aggressive. Experimental studies (e.g. Hermans et al.) show effects on threat processing, not on aggressive behaviour itself.
"Venting anger reduces aggression (catharsis)." This is one of the most persistent myths. Research consistently shows that catharsis increases rather than decreases hostility.
"Stress is purely psychological." Stress has measurable biological components: cortisol, autonomic arousal and immune changes. Social evaluative threat produces cortisol responses as reliably as physical stressors.
"Any stressor will produce a cortisol spike." Emotion induction and noise exposure alone do not reliably elevate cortisol. The combination of social evaluation and uncontrollability is what drives the strongest response.
⚠️ Know the distinction between instrumental and hostile aggression with examples of each
⚠️ Be able to explain why catharsis does not work and what the research shows instead
⚠️ Understand the challenge hypothesis (testosterone in animals) and why the evidence in humans is weaker
⚠️ Be prepared to list situational factors that increase aggression (weapons effect, social exclusion, poverty, heat, modelling)
⚠️ Know Selye's three-stage GAS model (alarm, resistance, exhaustion)
⚠️ Dickerson and Kemeny's meta-analysis is a likely exam topic: know what social evaluative threat and uncontrollability are, and why their combination produces the strongest cortisol response
⚠️ Be able to distinguish problem-focused from emotion-focused coping and state when each is most effective
True or false: Instrumental aggression is impulsive and driven by anger.
False. Instrumental aggression is goal-directed. Hostile (emotional) aggression is the impulsive, anger-driven type.
Fill in the blank: Selye's three stages of the stress response are ______, ______ and ______.
Alarm, resistance and exhaustion.
True or false: Catharsis (venting anger) reduces subsequent aggression.
False. Catharsis increases hostility.
Fill in the blank: According to Dickerson and Kemeny, the strongest cortisol responses occur when a stressor is both ______ and ______.
Socially evaluative and uncontrollable.
True or false: Problem-focused coping is always better than emotion-focused coping.
False. Problem-focused coping is better when you can control the situation. Emotion-focused coping is more effective when you cannot.
Q: Distinguish between instrumental and hostile aggression. Give one example of each.
A: Instrumental aggression is performed to achieve a specific goal (e.g. a soldier fighting in combat, a child hitting to get a toy). Hostile aggression is impulsive, driven by anger, and aims primarily to hurt (e.g. punching someone in a rage after being insulted).
Q: What is the challenge hypothesis, and how does the evidence differ between animals and humans?
A: The challenge hypothesis states that testosterone rises in response to challenges to dominance (e.g. breeding competition, territory disputes) and only enhances aggression in those challenge situations. In animals (e.g. chimps), this link is clearer. In humans, testosterone is associated with dominance but dominance is not always expressed through aggression, and the evidence is almost entirely correlational.
Q: Describe Selye's General Adaptation Syndrome. What happens at each stage?
A: Stage 1, Alarm: immediate sympathetic nervous system activation in response to a threat. Stage 2, Resistance: sustained arousal and immune activity, continued deployment of energy. Stage 3, Exhaustion: the body's resources are depleted after chronic stress, increasing vulnerability to disease.
Q: What did Dickerson and Kemeny's meta-analysis find about what produces the largest cortisol responses?
A: Tasks that combined social evaluative threat (being judged by others) with uncontrollability (inability to affect the outcome) produced the largest cortisol elevations and the slowest recovery. These were the only conditions in which cortisol failed to return to baseline within one hour. Emotion induction and noise exposure alone did not reliably produce significant cortisol responses.
Q: Compare problem-focused and emotion-focused coping. When is each most appropriate?
A: Problem-focused coping addresses the stressor itself (e.g. talking to a harasser's supervisor) and is most effective when the person has some control over the situation. Emotion-focused coping manages the emotional response (e.g. exercising, seeking social support, reframing) and is more effective when the situation is beyond the person's control.
Aggression connects back to conflict and violence in relationships (self-regulatory failure, the frustration-aggression hypothesis, displaced aggression). The stress material overlaps with prosocial behaviour (social exclusion is both a stressor and a trigger for reduced helping) and attraction (social rejection undermines the proximity and reciprocal liking processes that build relationships). The cortisol and coping material also provides the biological grounding for understanding why relationship conflict carries health consequences (immune suppression, cardiac risk) discussed in the relationship lectures.
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