Psychology’s Greatest Hits

56 landmark studies, case histories, and experiments that psychology keeps retelling

From obedience and conformity to memory, judgment, attachment, literacy, and research ethics

Why do we keep retelling the same psychology studies?

This article grew from a simple observation: across psychology textbooks, academic papers, popular science, and classroom material, the same experiments and case histories repeatedly reappear. Milgram’s shock generator, Zimbardo’s simulated prison, the marshmallow test, the bystander story, the Bobo doll, and many others have become familiar reference points far beyond the original research literature.

The purpose here is not to present a definitive list of the most important studies in psychology. Instead, it is to identify 56 studies, case histories, and research paradigms that have been especially persistent in American psychology, social science, cognitive science, and literacy/education writing. This compilation combines a broad review of psychology and social-science classics with a companion review of American literacy and reading-education research. It also highlights an important distinction: the studies most often remembered are not necessarily those supported by the strongest evidence.

The 56 studies, organized by theme

A.  Obedience, conformity, groups, and social influence

1. Milgram — Obedience Experiments

Authors: Stanley Milgram    |    Date: 1961–1963

Participants, placed in the role of “teachers,” were instructed by an authority figure to administer increasingly severe, fictitious electric shocks to a “learner” for wrong answers. A majority continued to dangerous levels. The study became the classic reference for obedience to authority and the ability of institutional situations to foster harmful behavior.

2. Stanford Prison Experiment

Authors: Philip Zimbardo    |    Date: 1971

College students were randomly assigned to “guards” or “prisoners” in a simulated prison. Guards rapidly became abusive and the study was terminated prematurely. It has traditionally been used to illustrate the influence of roles and situations on behavior, although subsequent work has strongly challenged this interpretation.

3. Deindividuation / Hooded Shock Study

Authors: Philip Zimbardo    |    Date: 1969

Participants who were anonymized by wearing hoods administered longer shocks than identifiable participants. The experiment became a conceptual link between anonymity, loss of individual identity, and group behavior.

4. Breaching Experiments

Authors: Harold Garfinkel    |    Date: 1960s

Sociology students deliberately violated ordinary rules of social interaction, for example by behaving like strangers in their own homes or demanding explanations for ordinary expressions. These “breaches” made visible the tacit rules that organize everyday social life.

5. Asch — Conformity Experiments

Authors: Solomon Asch    |    Date: 1951

Participants compared line lengths in the presence of confederates who unanimously gave an obviously wrong answer. Many conformed to the group. The study became a major reference on majority pressure, although Asch's original purpose was also to show that many people resist such pressure.

6. Robbers Cave Experiment

Authors: Muzafer Sherif    |    Date: 1954

Two groups of boys at a summer camp were placed in competition, which fostered intergroup hostility. Shared goals, or “superordinate goals,” subsequently helped reduce the conflict. It is a classic study of the formation and reduction of intergroup conflict.

7. Minimal Group Paradigm

Authors: Henri Tajfel    |    Date: 1970s

People were assigned to arbitrary groups with no meaningful differences between them. Even these minimal categories could produce favoritism toward one's own group. The paradigm became central to the study of social identity and prejudice.

8. Groupthink

Authors: Irving Janis    |    Date: 1972

Drawing on analyses of collective decisions, including American foreign-policy crises, Janis described how the desire for harmony and cohesion can reduce critical examination of alternatives and encourage poor decisions.

9. Social Loafing

Authors: Ringelmann; Latané, Williams & Harkins    |    Date: 1913; 1979

Research shows that individual effort may decrease when a person works in a group rather than alone, particularly in physical or collective-production tasks. The phenomenon became a standard reference in social psychology and organizational behavior.

10. Kitty Genovese / Bystander Story

Authors: Media case; social-psychology research    |    Date: 1964

The media account of a murder supposedly witnessed by many people who failed to intervene helped popularize the question of bystander apathy. Later investigations showed that the “38 witnesses” story was greatly exaggerated. It is primarily the narrative trigger for a series of experimental studies.

11. Bystander Intervention Experiments

Authors: John Darley & Bibb Latané    |    Date: From 1968

Experiments compared participants alone or in groups when confronted with an emergency. They demonstrated diffusion of responsibility and the role of social context in the likelihood of intervening.

12. Good Samaritan Study

Authors: Darley & Batson    |    Date: 1973

Seminary students, some placed under time pressure, encountered an apparently distressed person before giving a talk on the Good Samaritan. Participants who were rushed were less likely to help, illustrating the influence of time pressure on prosocial behavior.

13. Cognitive Dissonance — $1 vs. $20

Authors: Leon Festinger & James Carlsmith    |    Date: 1959

Volunteers were paid either 1 or 20 dollars to say that a boring task was interesting. The $1 group subsequently reported a more favorable attitude toward the task. The experiment became the classic demonstration of cognitive dissonance and insufficient external justification.

14. When Prophecy Fails

Authors: Festinger, Riecken & Schachter    |    Date: 1956

Researchers studied a group convinced that a worldwide catastrophe would occur. When the prophecy failed, believers did not necessarily abandon their conviction, and some strengthened it. The field study became a foundational narrative of cognitive dissonance.

15. Foot-in-the-Door / Door-in-the-Face

Authors: Freedman & Fraser; Cialdini et al.    |    Date: 1966; 1975

Two persuasion techniques became classics: obtaining agreement to a small request before making a larger one or beginning with an excessive request before proposing a more reasonable one. They are widely used to explain compliance and persuasion.

16. Over justification Effect

Authors: Lepper, Greene & Nisbett    |    Date: 1973

Children received external rewards for an activity they already enjoyed. After the reward was introduced, their intrinsic motivation for the activity declined. The study became a classic of motivation research.

17. Mere Exposure Effect

Authors: Robert Zajonc    |    Date: 1968

Repeated exposure to a stimulus can increase liking for it, even without explicit conscious recognition. The phenomenon has been particularly influential in social psychology, persuasion, and advertising.

B.  Attachment, development, learning, and behavior

18. Harlow — Wire Mother / Cloth Mother

Authors: Harry Harlow    |    Date: 1950s–1960s

Infant rhesus monkeys had access to a wire surrogate mother that provided milk and another covered with cloth. They spent more time with the soft mother, helping demonstrate that contact comfort plays a major role in attachment.

19. Ainsworth — Strange Situation

Authors: Mary Ainsworth    |    Date: 1969–1978

In a structured procedure, a parent briefly leaves the child, a stranger enters, and the parent returns. The child's reactions are used to distinguish attachment patterns, including secure, avoidant, and resistant attachment.

20. Visual Cliff

Authors: Eleanor Gibson & Richard Walk    |    Date: 1960

Infants were placed on a glass surface designed to create the appearance of a drop-off. Many avoided the apparent cliff. The experiment became a standard reference in research on depth perception and perceptual-motor development.

21. Still Face Experiment

Authors: Edward Tronick    |    Date: 1970s

A parent interacts normally with an infant and then suddenly adopts a motionless, expressionless face. The infant quickly shows distress and attempts to restore interaction. The procedure became a major example of early social regulation.

22. Bobo Doll Experiment

Authors: Albert Bandura    |    Date: 1961

Children watched an adult hit an inflatable Bobo doll. Children exposed to the aggressive model were more likely to imitate aggressive behavior. The study played a foundational role in social learning theory and debates about violent media.

23. Piaget — Conservation Tasks

Authors: Jean Piaget    |    Date: 1950s–1960s

Children confronted with containers of different shapes could judge that a taller glass contained more liquid even when the quantity was identical. These tasks were used to illustrate limits of preoperational reasoning and cognitive changes during development.

24. Genie — Feral Child Case

Authors: Case study of Genie    |    Date: Discovered in 1970

A girl who had experienced severe deprivation of social contact and language exposure was discovered in California at nearly 14. Her history became a central, but ethically complex, case in debates about critical periods in language development.

25. Clark Doll Test

Authors: Kenneth & Mamie Clark    |    Date: 1940s

Black children were asked to choose between Black and white dolls and to attribute qualities to them. The findings were interpreted as revealing psychological effects of segregation on self-image and were used in the context of Brown v. Board of Education.

C.  Memory, perception, attention, and judgment

26. Rosenhan Experiment

Authors: David Rosenhan    |    Date: 1973

People without mental illness reported a single symptom to obtain psychiatric admission and then behaved normally. The study was presented as demonstrating the power of diagnosis and institutional labeling. Its account is now strongly debated.

27. Loftus & Palmer — Eyewitness Memory

Authors: Elizabeth Loftus & John Palmer    |    Date: 1974

The wording of a question after an automobile accident, particularly terms such as “smashed” rather than “hit,” influenced participants' estimates. The work became a major reference on the malleability of eyewitness memory.

28. Lost in the Mall / False Memory

Authors: Elizabeth Loftus    |    Date: 1990s

Research examined whether autobiographical memories of events that had not occurred could be induced, including memories of being lost in a shopping mall. It strongly influenced research on false memory and suggestibility.

29. Sperling — Iconic Memory / Partial Report

Authors: George Sperling    |    Date: 1960

A grid of letters was presented very briefly. A partial-report procedure showed that participants briefly had access to a large amount of visual information that rapidly disappeared. It is a classic study of sensory memory.

30. Miller — Magical Number Seven

Authors: George A. Miller    |    Date: 1956

Miller synthesized research on limits of information processing and popularized the idea of “seven, plus or minus two.” The phrase became ubiquitous in cognitive psychology, although later work produced lower, task-dependent estimates.

31. They Saw a Game

Authors: Hastorf & Cantril    |    Date: 1954

Students from Princeton and Dartmouth watched the same football game but perceived differently the number of fouls committed by the two teams. The study illustrates selective perception and the influence of group affiliation on judgment.

32. Halo Effect

Authors: Edward Thorndike; Nisbett & Wilson    |    Date: 1920; 1977

A positive overall impression of a person can influence judgments of distinct characteristics, such as competence or kindness. The phenomenon became a standard reference in social psychology, recruitment, marketing, and interpersonal judgment.

33. Invisible Gorilla

Authors: Daniel Simons & Christopher Chabris    |    Date: 1999

Participants counted basketball passes and some failed to notice a person in a gorilla suit crossing the scene. The study became the emblematic demonstration of inattentional blindness.

34. Framing & Anchoring

Authors: Daniel Kahneman & Amos Tversky    |    Date: 1970s–1980s

Identical choices framed as gains or losses can produce different preferences, while an arbitrary initial number can influence a subsequent estimate. These paradigms profoundly shaped research on judgment and behavioral economics.

35. Rubber Hand Illusion

Authors: Botvinick & Cohen; later work    |    Date: 1990s onward

When synchronized visual and tactile stimulation is applied to a visible fake hand and the participant's hidden real hand, some people experience the fake hand as belonging to their own body. The paradigm examines body representation and the sense of bodily ownership.

D. Conditioning, motivation, self-control, and behavior

36. Little Albert

Authors: John B. Watson & Rosalie Rayner    |    Date: 1920

An infant was exposed to a white rat paired with a loud noise in order to condition a fear response. Generalization to other furry objects was reported. The study became a classic of emotional conditioning, but its interpretation and methodology have been subject to important historical criticism.

37. Skinner — Superstition in the Pigeon

Authors: B. F. Skinner    |    Date: 1948

Pigeons received food according to a schedule independent of their behavior. Some developed repetitive behaviors that appeared to associate their own actions with food delivery. The study is often used to explain the behavioral origins of superstition.

38. Learned Helplessness

Authors: Martin Seligman & Steven Maier    |    Date: 1967

Dogs that had previously experienced inescapable shocks later failed to use an available escape opportunity. The phenomenon was interpreted as learning that one's actions had no control and strongly influenced research on motivation and depression.

39. Rat Park

Authors: Bruce Alexander    |    Date: 1970s

Rats placed in a socially enriched environment consumed less morphine-laced water than isolated rats in standard cages. The study has often been invoked to argue that social and environmental conditions contribute to addictive behavior.

40. Marshmallow Test

Authors: Walter Mischel    |    Date: Late 1960s–1970s

Children could eat a treat immediately or wait to receive more later. The ability to wait was associated with better later outcomes. Larger and more diverse studies, however, substantially reduced the predictive strength of the original popularized claims.

41. Monster Study

Authors: Wendell Johnson    |    Date: 1939

Orphaned children at the University of Iowa were given negative speech therapy in an attempt to induce stuttering. Less a scientific finding than a cautionary case, it is constantly cited in research-ethics discussions alongside Little Albert and the Tuskegee Syphilis Study.

E.   Social cognition, moral judgment, and decision-making

42. Fundamental Attribution Error

Authors: Lee Ross    |    Date: 1977

People tend to explain others' behavior in terms of personal dispositions while underestimating situational constraints. The concept became one of the most frequently cited notions in social psychology.

43. Just-World Hypothesis

Authors: Melvin Lerner    |    Date: From 1965

People may tend to believe that the world is fundamentally fair, which can lead them to attribute some responsibility for misfortune to its victims. The concept is used in research on prejudice and victim blaming.

44. False Consensus Effect

Authors: Ross, Greene & House    |    Date: 1977

Individuals overestimate the proportion of people who share their beliefs, preferences, or behaviors. The phenomenon became a standard concept in social cognition.

45. Implicit Association Test

Authors: Greenwald, McGhee & Schwartz    |    Date: 1998

A reaction-time test measures how easily participants associate categories, such as social categories, with positive or negative words. The paradigm is central to research on implicit associations, although its ability to predict actual behavior is debated.

46. Milgram — Small World

Authors: Stanley Milgram    |    Date: 1967

A letter-forwarding experiment estimated the length of social chains connecting individuals. It became one of the origins of the popular concept of “six degrees of separation” and a reference point in social-network research.

47. Trolley Problem in Moral Psychology

Authors: Greene et al.; philosophical origins Foot/Thomson    |    Date: 1967–2001 and later

The trolley dilemma asks whether a vehicle should be diverted to save five people at the cost of one person's life. Originally philosophical, it became an experimental paradigm in moral psychology, including research on emotional and utilitarian judgment.

48. Prisoner's Dilemma & Ultimatum Game

Authors: Game-theory paradigms    |    Date: 20th century; later experimental adoption

These games are used to study cooperation, trust, fairness, reciprocity, and punishment. They are cross-disciplinary paradigms in social psychology, behavioral economics, and evolutionary psychology.

F.   Ethics, medicine, and large-scale social experimentation

49. Tuskegee Syphilis Study

Authors: U.S. Public Health Service    |    Date: 1932–1972

The U.S. Public Health Service followed Black men with syphilis in Alabama for decades without providing informed consent or offering effective treatment after penicillin became available. The study became a central reference in discussions of research ethics, informed consent, exploitation, and distrust in medical research.

50. Facebook Emotional Contagion Study

Authors: Kramer, Guillory & Hancock    |    Date: 2014

Researchers experimentally altered the proportion of positive or negative emotional content shown in users’ Facebook news feeds and measured changes in the emotional tone of users’ own posts. The study became a widely discussed example of large-scale online experimentation and raised important questions about consent, platform research, and emotional contagion.

51. Beecher — The Powerful Placebo

Authors: Henry K. Beecher    |    Date: 1955

Beecher reviewed clinical trials and argued that a substantial proportion of patients could improve after receiving placebos. The paper became highly influential in discussions of placebo effects and clinical trials, although later methodological work has challenged simple interpretations of its reported placebo response rate.

G. Literacy, reading, and educational research

52. Hart & Risley — 30 Million Word Gap

Authors: Betty Hart & Todd R. Risley    |    Date: 1995

A study of 42 Kansas City families found that children in professional households heard tens of millions more words by age three than children in families on public assistance, and that this predicted later language skill. It is among the most commonly cited pieces of American educational research, and also a frequent target of methodological criticism regarding its small sample and causal framing.

53. Stanovich — Matthew Effects in Reading

Authors: Keith Stanovich    |    Date: 1986

A framework describing how early reading struggles compound over time: poor decoders read less, fall further behind in vocabulary and comprehension, and widen the gap with skilled readers (“rich get richer, poor get poorer”). Treated as a seminal paper and invoked constantly in discussions of the American reading achievement gap.

54. National Reading Panel Report

Authors: Snow et al. (National Reading Panel)    |    Date: 2000

A U.S. government-commissioned review identifying five essential components of reading instruction: phonemic awareness, phonics, fluency, vocabulary, and comprehension. It is the most frequently invoked policy document underlying American reading-instruction mandates, including No Child Left Behind–era curricula.

55. Simple View of Reading

Authors: Philip Gough & William Tunmer    |    Date: 1986

A formula stating that reading comprehension equals decoding ability multiplied by language comprehension. Constantly recycled in both the historical “reading wars” and the more recent “science of reading” movement in American literacy education.

56. Shaywitz — fMRI Studies of Dyslexia

Authors: Sally Shaywitz et al. (Yale)    |    Date: late 1990s–2000s

Brain-imaging research showing that dyslexic readers activate different neural pathways than typical readers during reading tasks. The standard citation for framing dyslexia as a neurobiological, rather than purely behavioral or motivational, difference.

A final perspective: the psychology of remembering psychology

Taken together, these 56 entries form a kind of map of psychology’s collective memory. The most persistent narratives revolve around obedience, conformity, group behavior, helping, cognitive dissonance, attachment, memory, judgment biases, and—within American education research—reading achievement and literacy instruction.

Several entries are not single experiments at all. They are case studies, paradigms, historical episodes, or broader research programs. They remain influential because their stories became recurring teaching and writing references.

The central caution is therefore simple: a study’s fame should invite curiosity, not automatic acceptance. The most useful way to revisit a classic experiment is to ask not only “What did this study show?” but also “How was it conducted?”, “What exactly did the evidence support?”, “What happened in later research?”, and “Why did this particular story become so memorable?”

That shift—from remembering famous findings to examining how evidence is remembered—is perhaps the most valuable lesson this collection offers.