This is the 2007 version. Click here for the 2017 chapter 15 table of contents.

Asch (1951): Conformity

Perhaps the most influential study of conformity came from Solomon E. Asch (1951). Asch gave groups of seven or nine college students what appeared to be a test of perceptual judgment: matching the length of a line segment to comparison lines. Each subject saw a pair of cards set up in front of the room, similar to the ones that follow.

Stimuli like those used by Asch

What was Asch's classic experiment on conformity?

Subjects received the following instructions:

This is a task involving the discrimination of lengths of lines. Before you is a pair of cards. On the left is a card with one line. The card at the right has three lines different in length; they are numbered 1,2, and 3, in order. One of the three lines at the right is equal to the standard line at the left-you will decide in each case which is the equal line. You will state your judgment in terms of the number of the line. There will be 18 such comparisons in all... As the number of comparisons is few and the group small, I will call upon each of you in turn to announce your judgments.

In a group of nine, eight subjects were actually confederates of the experimenter. The experiment was rigged so that the genuine (na´ve) subject was called upon next-to-last in the group. The experimenter's confederates had been instructed, in advance, to make deliberately ridiculous judgments on many of the trials, but to agree unanimously with one another. On 12 of the 18 trials, they said in loud voices (for example) that the 4 1/2" line was exactly equal to 3" standard line.

The pressure of the group had a dramatic effect. Although people could pick the correct line 99% of the time when making the judgments by themselves, they went along with the erroneous group judgment 75% of the time, even when it was plainly wrong.

How did Asch's subjects rationalize making obviously wrong judgments?

The conforming subjects did not fool themselves into thinking the wrong line was equal to the standard line. They could see the difference. However, they were influenced by eight people in a row making the "wrong" decision. Asked later why they had made such obviously incorrect judgments, subjects reported, "They must have been looking at line widths" or "I assumed it was an optical illusion" or "If eight out of nine people made the same choice, I must have missed something in the instructions."

Asch obtained the conformity effect even when the confederate declared an eleven-inch line to be equivalent to a four-inch standard. He found that small groups-even groups of three, containing two confederates and one na´ve subject-were sufficient to induce the effect.

How many subjects remained independent and did not conform?

About a quarter of the subjects remained independent throughout the testing and never changed their judgments to fit those of the group. One could argue that Asch's experiment showed stubborn independence in some people, just as it showed conformity in others. A subject who did not conform reported to Asch later:

I've never had any feeling that there was any virtue in being like others. I'm used to being different. I often come out well by being different. I don't like easy group opinions.

What happened when there was a dissenter in the group? If responses were written in private?

Asch later tested the effect of having a dissenter in the group. He found that if only one of seven confederates disagreed with the group decision, this was enough to free most subjects from the conformity effect. However, if the dissenter defected later, joining the majority after the first five trials, rates of conformity increased again. The public nature of the judgment also seemed to have an effect. If subjects were invited to write their responses in private, while the majority made oral responses, this destroyed the conformity effect.

Asch's experiment inspired a lot of follow-up research by other experimenters. Factors found to increase conformity included the following:

What factors increased conformity?

1. Attractiveness of other members in the group (people tended to go along with a group of attractive people)

2. Complexity or difficulty of the task (people were more likely to conform if the judgment was difficult).

3. Group cohesiveness (people conformed more if friendships or mutual dependencies were set up beforehand).

How do we explain the power of the pressure to conform? Ross, Bierbauer and Hoffman (1976) point out that the conformity situation may have been more pressure-packed than most people appreciate.

To appreciate further the nature of this dilemma, let us imagine an introductory lecture in psychology. The instructor is describing the Asch study and has just shown a picture of the experimental stimuli. Suddenly he is interrupted by a student who remarks, "But line A is the correct answer..." Predictably, the class would laugh aloud and thereby communicate their enjoyment of their peer's joke. Suppose, however, that the dissenter failed to smile or to otherwise confirm that he was trying to be funny. Suppose, instead, that he insisted, "Why are you all laughing at me? I can see perfectly, and line A is correct." Once convinced of the dissenter's sincerity, the class response almost certainly would be a mixture of discomfort, bewilderment, concern, and doubt about the dissenter's mental and perceptual competence. It is this response that the Asch dissenters risked and, accordingly, it is not surprising that many chose to avoid it through conformity.

What did NBC find out, in 1997?

Was the Asch conformity effect possibly due to the era in which it was carried out? After all, the early 1950s were famous for emphasizing conformity, such as the "corporate man" who did everything possible to eliminate his individuality and fit into a business setting. To see if the same experiment would work with a later generation of subjects, NBC news had social psychologist Anthony Pratkanis replicate the Asch experiment in front of a hidden camera for its Dateline show in 1997. Sure enough, the experiment still worked, and the percentage of conformists was almost identical to what Asch found. Most students, even some who looked creative or rebellious on the outside, went along with obviously incorrect group judgments. Later they explained that they did not want to look foolish, so they just "caved in."

Write to Dr. Dewey at

Don't see what you need? Psych Web has over 1,000 pages, so it may be elsewhere on the site. Do a site-specific Google search using the box below.

Custom Search

Copyright © 2007-2011 Russ Dewey