Asch Experiment: Bases, Procedure and Results

He Asch experiment Focused on examining the power of conformity in groups. It is a series of studies carried out in 1951. This experiment was based on the study of the Social psychology .

A group of students who participated in a vision test were encouraged to perform the study. However, without their knowledge, they were part of a psychological study.

The asch experiment with its creator

The experiment also included subject controls, ie people who were aware of being involved in a psychological study and who also acted as accomplices of the experimenter.

At present, the Asch experiment is one of the Social psychology studies More widely known worldwide and the results obtained have produced a high impact on social psychology and group psychology.

This article explains the Asch experiment, discusses the procedure that was followed and the tests that were performed, and reviewed the results that were obtained through this study.

Bases of the Asch experiment

The Asch experiment is one of the Most famous and well-known studios Within the field of social psychology. This was designed and developed by Solomon Asch And its main objective was to test how peer pressure can change people's behavior.

In this sense, the Asch experiment is directly related to the experiments conducted in the Stanford Prison and the Experiments by Milgram . These two studies examined the social influence on the individual behavior of each subject.

More specifically, Asch's experiment tries to show how humans with totally normal conditions can feel pressured to such an extent that their own pressure leads them to modify their behavior and even their thoughts and convictions.

Asch Experiment: Bases, Procedure and Results

In this sense, Asch's experiment shows that peer pressure can cause a subject to see his / her judgment and personal behavior influenced.


The Asch experiment was developed by bringing together a group of 7 to 9 students in a classroom.

Participants had been told that they would perform a vision test, so they would have to carefully observe a continuum of images.

More specifically, upon reaching the classroom, the experimenter indicated to the students that the experiment would consist of comparing a series of pairs of lines.

Each subject would be shown two cards, one would appear a vertical line and the other three vertical lines of different length. Each participant should indicate which of the three lines of the second card had the same length as the line of the first card.

Although the experiment had about 9 participants, in fact, all but one were subject controls. That is, they were accomplices of the researcher, whose behavior was aimed at contrasting the hypotheses of the experiment and, therefore, to exert social pressure on the remaining participant (critical subject).


The experiment began by showing the cards to the participants. All of them visualized the same card with a line and another card with three lines.

The study was designed in such a way that the critical subject had to choose the line of identical length to that of the other card once the other participants (accomplices) had made their assessment.

In total, the experiment consisted of 18 different comparisons of which the accomplices were instructed to give an incorrect answer in twelve of them.

In the first two cards, both the accomplices and the critical subject responded correctly, indicating the line of the card that was of identical length to the line of the other card.

However, from the third test the accomplices began to intentionally indicate an incorrect answer. In this third comparison, the critical subject differed from the others and manifested the correct assessment by being surprised by the other incorrect answers.

In the fourth comparison the pattern was maintained and the accomplices determined unanimously an incorrect answer. In this case, the critical subject showed a remarkable bewilderment but was able to make the correct answer.

During the other 10 comparisons, the accomplices maintained their pattern of conduct, always making an incorrect response on the cards. From that moment, the critical subject began to yield to pressure eventually and also indicate an incorrect response.


The experiment discussed above was repeated with 123 different participants (critical subjects).

In the results it was observed that in normal circumstances the participants gave an erroneous answer 1% of the times, reason why the task did not present difficulty.

However, when social pressure appeared, the participants allowed 36.8% of the time to take the wrong view of others.

Likewise, although most of the critical subjects (more than half) answered correctly, many of them experienced high discomfort and 33% of them settled for the majority view when at least three accomplices were present.

On the other hand, when the accomplices did not issue a unanimous judgment, the percentage of success of the critical subject increased markedly when all the accomplices agreed on an incorrect answer.

In contrast, when subjects performed the same task without being exposed to other people's opinions, they had no problem determining the correct response.

Thus, Asch's experiment made it possible to show the high potential of social pressure on human judgment and behavior.

An important difference between the Asch experiment and the well-known Milgram experiment lies in the attribution of erroneous behaviors.

In the Asch experiment, subjects attributed their erroneous responses to defects in their visual capacity or lack of judgment (internal attribution). Instead, in Milgram's experiment, participants blamed the attitude and behavior of the experimenter (external attribution).


  1. Asch, S. E. (1956). Studies of independence and conformity: A minority of one against a unanimous majority. Psychological Monographs, 70 (Whole No. 416).
  2. Bond, R., & Smith, P. (1996). Culture and conformity: A meta-analysis of studies using Asch's (1952b, 1956) line judgment task.Psychological Bulletin, 119, 111-137.
  3. Lorge, I. (1936). Prestige, suggestion, and attitudes, Journal of Social Psychology, 7, 386-402.
  4. Miller, N.E. & Dollard, J. (1941). Social learning and imitation. New Haven, CT: Yale University Press.
  5. Moore, H.T. (1921). The comparative influence of majority and expert opinion, American Journal of Psychology, 32, 16-20.

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