The aim of Asch’s (1951) experiment was to investigate the extent to which group pressure influences an individual’s judgement, even when the correct answer is obvious. In other words, the study sought to determine whether a person would conform to a majority’s clearly incorrect response in a simple perceptual task.
Sample:
Asch used a sample of 123 male American undergraduate students. These participants were unaware that all but one member of the group were confederates (actors) working with the experimenter.
Task and Set-Up:
Participants were placed in small groups, typically consisting of 7 to 9 people. They were told that they were taking part in a visual perception test. The task involved comparing the length of a ‘standard’ line with three comparison lines and identifying which of the comparison lines was the same length as the standard.
Arrangement of Confederates and Critical Trials:
In each group, all the confederates were instructed to give the same incorrect answer on 12 out of the 18 trials – these were the ‘critical trials’. The real participant was positioned so that he would be next-to-last, ensuring that he heard the unanimous (but wrong) responses of the confederates before giving his own answer.
Findings
From the 12 critical trials:
On average, participants conformed to the incorrect group response on approximately 33% of these trials.
Overall, 75% of the participants conformed to the group’s incorrect answer at least once.
A small minority (about 5% of participants) conformed on all 12 critical trials.
