What textbook are you using? I can probably use my sources to find the actual answer. Here's a video though that will explain the experiment well:
The experimenter arrives and tells you that the study in which you are about to participate concerns people's visual judgments. She places two cards before you. The card on the left contains one vertical line. The card on the right displays three lines of varying length.
![](http://www.age-of-the-sage.org/psychology/social/asch_conformity.gif)
The experimenter asks all of you, one at a time, to choose which of the three lines on the right card matches the length of the line on the left card. The task is repeated several times with different cards. On some occasions the other "subjects" unanimously choose the wrong line. It is clear to you that they are wrong, but they have all given the same answer.
What would you do? Would you go along with the majority opinion, or would you "stick to your guns" and trust your own eyes?
In 1951 social psychologist Solomon Asch devised this experiment to examine the extent to which pressure from other people could affect one's perceptions. In total, about one third of the subjects who were placed in this situation went along with the clearly erroneous majority.