Solomon Eliot Asch (1907-1996) was a Polish-American gestalt psychologist and pioneer in social psychology. He created pieces of work in impression formation, prestige suggestion, conformity, and many other topics in social psychology.
Solomon Asch conducted an experiment to investigate the extent to which social pressure from a majority group could affect a person to conform. In 1951, he created and conducted a social psychology experiment, where he asked a participant to give an answer, while the rest of the group disagreed with them to see how much the participant would give into group pressure.
He used a lab experiment with 50 male students from Swarthmore College and told them that they were participating in a vision test. Using a line judgment task, he put the participant with seven other students who were part of the experiment. The seven students agreed in advanced what their answer would be when presented with the line task. The participant thought that they were all participating in the experiment.
The experimenter stood in the front of the room and held up a display with one comparison line and the students were told to choose the line (out of three) that was the same length. Each person in the room would state their answer line (A, B, or C) out loud. The real participant was sat at the end of the row and would give their answer last.
There were 18 trials in total and the seven students who were in on the experiment purposely gave the wrong answer 12 times. The point of the experiment was to see if the real participant would give the right answer or if they would conform to the majority.
There was also another experiment where there were no other students who were part of the experiment, just a real participant.
Here is a YouTube video of a clip from the experiment: LINK
Asch measured the number of times each participant conformed to the majority view. On average, about 1/3 of the participants who were placed in this situation went along and conformed with the clearly incorrect majority.
Throughout 12 trials, about 3/4 of participants conformed at least once and 1/4 of participants never conformed. In the control group where there was no pressure from other students who were part of the experiment, less than 1% of participants gave the wrong answer.
When participants were interviewed after the experiment, most of them said that they did not believe their conforming answers, but they went along with the group out of fear of being ridiculed. A few of them stated that they really thought that the group’s answer was correct.
The experiment concluded that people conform for two main reasons: they want to fit in with the group (normative influence) and because they believe the group is more informed than they are (informational influence).
Asch, S. E. (1951). Effects of group pressure upon the modification and distortion of judgment. In H. Guetzkow (ed.) Groups, leadership and men. Pittsburgh, PA: Carnegie Press.
Asch, S. E. (1956). Studies of independence and conformity: I. A minority of one against a unanimous majority. Psychological monographs: General and applied, 70(9), 1-70.