Asch’s experiment

The experiments in accordance with the group of Asch were a series of experiments realized in 1951 that demonstrated significantly the power of the conformity in the groups.

The experimenters, led by Solomon Asch, asked some students to participate in a “vision test”. In fact all but one of the participants in the experiment were accomplices to the experimenter and the experiment was actually to see how the remaining student reacted to the behavior of the accomplices. The explicit aim of the research was to study the conditions that induce individuals to remain independent or to submit to group pressures when they are contrary to reality.

The participants – the real subject and the accomplices – were all sitting in a class room where they were asked to say what was in their mind the length of several lines drawn in a series of exhibitions: they were asked if a line was Longer than another, which had the same length, etc. The accomplices had been trained to give incorrect answers in the tests and to determine if this influenced the responses of the other student.


A group of 7 to 9 students met in a classroom and the experimenter indicated that the experiment would consist of comparing pairs of lines. They would be shown two cards, one would appear a vertical line and the other three vertical lines of different length. Participants should then indicate which of the three lines on the second card had the same length as the standard on the first card.

Of the group of participants, all but one were actually accomplices of the researcher, the remainder (subject critical) being the focus of the experiment, which was placed in the position of having to give his answer after having heard most of the answers of others. The experiment consisted of carrying out 18 comparisons of cards with accomplices having the instruction to give an incorrect answer in 12 of them.

In the first two, both the accomplices and the critical subject responded unanimously to the correct answer. However, from the third test, the accomplices intentionally indicate an incorrect response. In this, the subject gives the correct answer at the end, being surprised by the previous (and incorrect) answers of the accomplices. In the following test the situation is repeated: the accomplices unanimously give an incorrect answer and the critical subject dissent giving the correct answer but showing a greater bewilderment. When the situation is repeated, the critical subject eventually yields to the group pressure and also indicates an incorrect response.


The experiment was repeated with 123 different participants. It was found that although in normal circumstances the participants gave a wrong answer 1% of the time, the presence of the group pressure caused that the participants were left with the incorrect option 36.8% of the time. 1

Although most subjects answered correctly, many showed extreme discomfort and a high proportion of them (33%) settled for the majority view of the others when there were at least three accomplices present, even though most said that two Lines with several centimeters of difference length were the same. When the accomplices did not issue a unanimous judgment, the subject was more likely to disagree than when they all agreed. Subjects who were not exposed to the majority opinion had no problem in giving the correct answer.

A difference between Asch’s conformance experiment and the also famous in Milgram’s social psychology experiment led by Stanley Milgram is that the subjects in that study attributed the result to their own “bad view” or lack of judgment, whereas in the experiment Of Milgram blamed the experimenter for his behavior.

Asch experiments may provide some evidence empirical relevant to some of the ideas in the novel 1984 by George Orwell . It also serves to illustrate the concept of “take a deer and call it a horse” (指鹿為馬 / 指鹿为马), a test of loyalty to his subordinates by Zhao Gao .


  • Effects of group pressure upon the modification and distortion of judgment. In H. Guetzkow (ed.) Groups, leadership and men . Pittsburgh, PA: Carnegie Press ( summary here )
  • Asch, SE (1956). Studies of independence and conformity: A minority of one against a unanimous majority. Psychological Monographs , 70 (Whole No. 416)
  • Asch, S. (1974). Group forces in the modification and distortion of judgments. In JR Torregrosa and E. Crespo. (Comps.), Basic studies of social psychology . (Pp. 351-364). Barcelona: Hour
  • 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. PDF
  1. Back to top↑ Asch, Solomon E. (November 1955). Opinions and Social Pressure. Scientific American 193 (5): 31-35.