Most of us believe we would act on our values no matter what others around us were doing. Social psychology, the study of how people think about, influence and relate to one another, has repeatedly tested that belief. Some of its most famous experiments suggest that ordinary situations can push ordinary people to do surprising things. Others show how those pressures can be resisted, and how hostility between groups can be reduced. This level covers the classic findings, along with the debates that have grown up around them.

Conformity: Asch's lines

In the early 1950s Solomon Asch invited students to take part in what they thought was a vision test. Each was seated with a group of others, all secretly working with the experimenter, and asked to say which of three lines matched a reference line in length. The answer was obvious. But on certain trials, the whole group confidently gave the same wrong answer. About three quarters of real participants went along with the group at least once, and overall they conformed on roughly a third of these trials. Yet Asch's results also carry hope: most answers were still independent, and when just one other person in the group gave the correct answer, conformity dropped sharply. A single ally makes dissent much easier.

Obedience: Milgram's shocks

In 1961, the year Adolf Eichmann went on trial, Yale psychologist Stanley Milgram began a series of experiments on obedience. Volunteers were told they were helping study learning and were asked to give electric shocks of increasing strength to a "learner" in the next room each time he made a mistake. The learner was an actor and received no shocks, but he cried out, complained of a heart condition and finally fell silent. In the best known version, published in 1963, 26 of 40 participants, or 65 percent, continued to the highest level, marked 450 volts. Many were visibly distressed but kept going when the experimenter calmly told them to continue.

Milgram ran many variations. Obedience fell when the experimenter gave orders by telephone, when the victim was in the same room, and especially when other "teachers" refused to continue. Later researchers have questioned how many participants truly believed the shocks were real, and noted that the experimenter sometimes went beyond the standard script. The studies also raised serious ethical concerns about deceiving and distressing volunteers. But the core finding, that people will often follow authority further than they predict, has been broadly supported.

Roles and the Stanford Prison Experiment

In 1971 Philip Zimbardo set up a mock prison in a Stanford basement, assigning students to be guards or prisoners. Some guards became cruel, and the study was stopped after six days instead of the planned two weeks. For decades it was taught as proof that roles alone can turn good people bad. Later investigations of the archives showed that guards were encouraged to be tough and that some behavior was performed for the researchers. Today many psychologists see it as a vivid demonstration rather than a rigorous experiment, and a reminder to read famous studies carefully.

Helping and the bystander effect

In 1964 a young woman named Kitty Genovese was murdered in New York, and a newspaper reported that 38 neighbors had watched and done nothing. The report was badly exaggerated, and at least one neighbor did call for help, but the story inspired John Darley and Bibb Latané to study helping. Their experiments found that people were less likely to help when they believed others were also present, partly because responsibility feels shared, or diffused. A 2019 study of real public conflicts caught on security cameras in three countries found that at least one bystander stepped in about nine times out of ten. Groups may make each individual less likely to act, but they also contain more potential helpers.

Us and them

Humans divide into groups remarkably easily. In the early 1970s Henri Tajfel found that even when people were sorted into groups by something trivial, like a preference for one painter over another, they favored their own group when sharing rewards. In the 1954 Robbers Cave study, Muzafer Sherif divided boys at a summer camp into two groups. Competitive games quickly produced name-calling and raids. Simply bringing the groups together did not help, but working on shared goals that neither could achieve alone, such as fixing the camp's water supply, reduced hostility. The same year Gordon Allport proposed the contact hypothesis: contact between groups reduces prejudice best under conditions such as equal status, cooperation and support from authorities. A 2006 analysis of more than 500 studies found that contact reliably reduces prejudice.

Worked example: speaking up at work

At a team meeting, a manager proposes cutting a safety check to meet a deadline. You think it is a bad idea, but everyone else nods. What does social psychology suggest? Asch shows that the pressure you feel is normal and that a single ally changes everything, so speaking first or quietly finding one colleague who agrees can make it easier for others to dissent. Milgram shows that authority can carry people further than they intend, which is why clear rules and a culture that welcomes questions matter. The bystander research reminds you not to assume someone else will raise the concern. Knowing these forces does not make them disappear, but it helps us recognize the situation and choose to act on our values anyway.