Why Do People Harm Others—and What Can Reduce It?

From the meaning of aggression to retaliation, social norms, and evidence for prevention.

Level: Introductory
Reading load: 9 core readings in 5 units
Prerequisites: No methods course is required. The guides introduce measurement, experimental comparisons, path models, and school-level trials. How Do Other People and Social Situations Shape Us? offers useful preparation. The Helping and Cooperation path provides a complementary account of motives, rules, and sanctions.
Last reviewed: September 2026

Introduction

Anger may pass without harm, while harm may be deliberate and unhurried. People retaliate, follow learned expectations, defend reputations, or regard injury as justified. Other people and institutions can restrain such conduct, reward it, or lend it an appearance of necessity. Explanation must identify these differences before asking what could reduce the harm that follows.

Begin with what aggression means and how it is measured. Use a broad framework to examine interpretations of provocation, then compare moral justification with culturally shaped expectations about honor. Follow the move from repeatedly dwelling on a provocation to retaliation carried out on behalf of a group. Finish with two school interventions that differ in who harms whom and how change is measured.

The aim is to explain a claim precisely enough to question it: what behavior occurred, what mechanism is proposed, which comparison supports it, and what evidence would show that prevention reduced harm?

Unit 1 of 5

What counts as aggression?

An argument, an angry feeling, an intended injury, and an accidental injury are different phenomena. Here, violence refers to severe physical aggression. Definitions determine what enters an explanation; measures determine what a study can actually show. Establish those distinctions before comparing theories.

Reading
1 of 9
A Conceptual Review of Lab-Based Aggression Paradigms
McCarthy, R. J., & Elson, M. (2018). A conceptual review of lab-based aggression paradigms. Collabra: Psychology, 4(1), Article 4. https://doi.org/10.1525/collabra.104
Methodological contribution · Critical reappraisal · Moderate · Full work: 12 pages
Compare the authors' criteria for aggression with the assumptions built into noise, hot-sauce, and symbolic tasks.
Why you’re reading it. Establish a standard for judging the measures used throughout this path.
A question to consider. A task records that someone assigns difficult puzzles to a stranger. What would you need to know before calling that behavior aggressive?

Unit 2 of 5

Which processes lead to harm?

A framework can organize possible causes without demonstrating all of them. Move from a proposed cycle of person, situation, and appraisal to a study of how children interpret ambiguous events. Keep explanation within a person separate from differences between people or sampled contexts.

Reading
2 of 9
The General Aggression Model
Allen, J. J., Anderson, C. A., & Bushman, B. J. (2018). The general aggression model. Current Opinion in Psychology, 19, 75–80. https://doi.org/10.1016/j.copsyc.2017.03.034
Major synthesis · Moderate · Full work: 6 pages
Use Figure 1 to trace how a provocation could produce either retaliation or restraint. Treat each arrow as a claim requiring evidence.
Why you’re reading it. Build a vocabulary for comparing mechanisms without reducing aggression to one trait or emotion.
A question to consider. Someone interprets a delayed reply as deliberate disrespect. What two pathways could connect that interpretation to a harmful response, and how would you distinguish them?
Reading
3 of 9
Hostile Attributional Bias and Aggressive Behavior in Global Context
Dodge, K. A., Malone, P. S., Lansford, J. E., Sorbring, E., Skinner, A. T., Tapanya, S., Uribe Tirado, L. M., Zelli, A., Alampay, L. P., Al-Hassan, S. M., Bacchini, D., Bombi, A. S., Bornstein, M. H., Chang, L., Deater-Deckard, K., Di Giunta, L., Oburu, P., & Pastorelli, C. (2015). Hostile attributional bias and aggressive behavior in global context. Proceedings of the National Academy of Sciences, 112(30), 9310–9315. https://doi.org/10.1073/pnas.1418572112
Landmark empirical study · Challenging · Full work: 6 pages
Connect the framework's appraisal process to the vignette measures, behavior reports, and three levels of comparison in this study.
Why you’re reading it. Evaluate a proposed mechanism across contexts while preserving the limits of observational evidence.
A question to consider. If hostile interpretations predict later aggression after controlling earlier aggression, what additional evidence would establish that changing the interpretation reduces harm?

Unit 3 of 5

How do norms and power shape aggression?

Harmful conduct can be defended as proper, necessary, or honorable. Examine how people justify acts and how social expectations give provocations meaning. Ask who defines the rules, whose reputation receives protection, and whose injury is discounted.

Reading
4 of 9
Mechanisms of Moral Disengagement in the Exercise of Moral Agency
Bandura, A., Barbaranelli, C., Caprara, G. V., & Pastorelli, C. (1996). Mechanisms of moral disengagement in the exercise of moral agency. Journal of Personality and Social Psychology, 71(2), 364–374. https://doi.org/10.1037/0022-3514.71.2.364
Foundational argument · Landmark empirical study · Moderate · Full work: 11 pages
Compare moral disengagement with the claim that aggression simply reflects insufficient thought or control.
Why you’re reading it. Recognize explanations in which people actively justify harm and redistribute responsibility.
A question to consider. An organization calls humiliating newcomers a tradition that builds commitment. Which proposed mechanisms might be involved, and what evidence would show that they enable the practice rather than merely excuse it afterward?
Reading
5 of 9
Insult, Aggression, and the Southern Culture of Honor: An ‘Experimental Ethnography’
Cohen, D., Nisbett, R. E., Bowdle, B. F., & Schwarz, N. (1996). Insult, aggression, and the southern culture of honor: An “experimental ethnography”. Journal of Personality and Social Psychology, 70(5), 945–960. https://doi.org/10.1037/0022-3514.70.5.945
Landmark empirical study · Moderate · Full work: 16 pages
Separate the experimentally varied insult from the participants' regional histories, then examine which responses changed and which did not.
Why you’re reading it. Evaluate a cultural explanation without converting a selected sample into a stereotype.
A question to consider. How could you investigate whether perceived expectations about reputation explain the response better than region alone?

Unit 4 of 5

How does retaliation escalate—or subside?

A response can keep a grievance active, invite another response, or shift harm to someone else. Begin with an experiment on attention during venting, then consider how revenge operates across relationships, organizations, and groups. A mechanism proposed at one level must earn its extension to another.

Reading
6 of 9
Does Venting Anger Feed or Extinguish the Flame? Catharsis, Rumination, Distraction, Anger, and Aggressive Responding
Bushman, B. J. (2002). Does venting anger feed or extinguish the flame? Catharsis, rumination, distraction, anger, and aggressive responding. Personality and Social Psychology Bulletin, 28(6), 724–731. https://doi.org/10.1177/0146167202289002
Landmark empirical study · Critical reappraisal · Accessible · Full work: 8 pages
Apply the measurement review to the noise task, and distinguish the anger results from the aggression results.
Why you’re reading it. Test an intuitively appealing claim against the actual experimental comparisons.
A question to consider. Would these results justify replacing all opportunities to discuss anger with silence? Explain the additional assumptions that conclusion would require.
Reading
7 of 9
Revenge: A Multilevel Review and Synthesis
Jackson, J. C., Choi, V. K., & Gelfand, M. J. (2019). Revenge: A multilevel review and synthesis. Annual Review of Psychology, 70, 319–345. https://doi.org/10.1146/annurev-psych-010418-103305
Major synthesis · Challenging · Full work: 27 pages
Follow the distinction between an individual's motive and a process sustained by group boundaries, norms, or institutions.
Why you’re reading it. Extend the account of retaliation beyond a single angry encounter.
A question to consider. After one team member harms another, uninvolved members begin retaliating. What might a credible grievance procedure change, and what outcomes could reveal continued or displaced harm?

Unit 5 of 5

What would show that prevention works?

A plausible mechanism does not guarantee an effective intervention. Compare a peer-network approach with a program addressing violence by school staff. Evaluate the assigned intervention, the outcome, uncertainty, remaining harm, and what would be required for effects to last or transfer.

Reading
8 of 9
Changing Climates of Conflict: A Social Network Experiment in 56 Schools
Paluck, E. L., Shepherd, H., & Aronow, P. M. (2016). Changing climates of conflict: A social network experiment in 56 schools. Proceedings of the National Academy of Sciences, 113(3), 566–571. https://doi.org/10.1073/pnas.1514483113
Methodological contribution · Landmark empirical study · Challenging · Full work: 6 pages
Use the linked corrections when evaluating the administrative conflict estimate. Separate peer influence, perceived norms, recorded incidents, and experienced harm.
Why you’re reading it. Learn why a promising intervention can provide useful evidence while its headline outcome remains uncertain.
A question to consider. A school reports fewer disciplinary incidents after a campaign. What additional measures would distinguish less harm from changes in reporting or enforcement?
Reading
9 of 9
The Good School Toolkit for Reducing Physical Violence from School Staff to Primary School Students: A Cluster-Randomised Controlled Trial in Uganda
Devries, K. M., Knight, L., Child, J. C., Mirembe, A., Nakuti, J., Jones, R., Sturgess, J., Allen, E., Kyegombe, N., Parkes, J., Walakira, E., Elbourne, D., Watts, C., & Naker, D. (2015). The Good School Toolkit for reducing physical violence from school staff to primary school students: A cluster-randomised controlled trial in Uganda. The Lancet Global Health, 3(7), e378–e386. https://doi.org/10.1016/S2214-109X(15)00060-1
Landmark empirical study · Moderate · Full work: 9 pages
Compare this primary outcome and adult–child power relationship with the peer-network intervention. Track both the difference between groups and the harm that remains.
Why you’re reading it. Evaluate a prevention package using evidence close to the intended outcome while retaining limits on mechanism and transfer.
A question to consider. Before extending the Toolkit to another district, what evidence would you seek about implementation, sustained effects, reporting, and children who remain exposed to violence?

Scope and omissions

This path introduces explanations of interpersonal and intergroup aggression through measurement, social cognition, moral justification, culture, retaliation, and school prevention. It includes conceptual reviews, laboratory experiments, longitudinal observations, and field trials.

It is not a comprehensive account of war, intimate-partner abuse, criminal justice, structural violence, or the biology of aggression. The optional works extend measurement, theory criticism, everyday aggression, arousal, forgiveness, and community prevention. The path does not equate mental disorder with violence or treat a region, sex, or group as inherently aggressive. Explaining a harmful act neither excuses it nor assigns responsibility to its recipient. Prevention and repair must take continued harm and unequal power seriously.

Synthesis

Harmful conduct can arise through interacting processes: perceived threat, pursued goals, shared expectations, justification, and retaliation. A useful account identifies the proposed process and the evidence that distinguishes it from alternatives. Anger, aggression, and violence remain different concepts, while a result obtained with one measure leaves its reach to other forms of harm to be established.

Prevention can target interpretations, social expectations, opportunities, or institutional practices. Its success depends on measured outcomes and credible comparisons, not merely on the appeal of its theory. The two school studies show why corrected estimates, uncertainty, reporting practices, and the amount of harm remaining all matter. Neither a laboratory effect nor a successful intervention package establishes every proposed mechanism.

Imagine a school with retaliatory peer conflict and staff who defend physical punishment as discipline. Propose one change to peer interactions and one to institutional practice. For each, identify the intended mechanism, a rival explanation, the people who might remain vulnerable, and evidence that would show sustained reduction in harm. Explain how your evaluation would detect displacement or changes in reporting.

Continue with How Do Groups Shape Identity and Collective Action? to examine collective coordination and change, or Why Do People Help and Cooperate? to compare helpful motives, institutions, and the consequences of sanctions. Return to How Do Other People and Social Situations Shape Us? for the wider area.