Asch's Lines and the Pressure of a Wrong Room

In 1951, the social psychologist Solomon Asch ran a deceptively simple experiment in a lab at Swarthmore College. He sat eight male undergraduates around a table and showed them pairs of cards. One card held a single vertical line. The other held three lines — A, B, and C. The subjects' task was to call out, in turn, which of the three matched the reference. The match was unmissable.

Seven of the eight were Asch's confederates. The eighth, the real subject, sat near the end of the line and heard most of the others answer first.

For the first two trials, the confederates answered correctly. On the third, they unanimously called the wrong line. They did so on twelve out of eighteen "critical" trials. Asch wanted to know how often a subject would side with his eyes and how often with the room.

Across roughly 50 subjects, about 37 percent of critical-trial answers went with the group's wrong call. Three quarters of subjects conformed at least once; a quarter never did. In a control run without confederates, almost no one made a mistake.

The follow-ups were the harder finding. Conformity rose sharply up to three confederates and then plateaued — extra bodies did not add pressure. It collapsed by about 80 percent if even one other confederate broke ranks and gave the right answer. And if subjects wrote their answers privately instead of speaking, conformity nearly disappeared.

Asch's reading of the data was not that people are weak. It was that being the only one in the room who can see what you're seeing is its own kind of work.