Proof of the self-fulfilling prophecy’s influence on outcomes in organizations was evident as long ago as 1890. The U.S. Census Bureau installed new tabulating machines that required census workers to learn new skills that were thought to be difficult. The workers were told that after some practice they would be able to punch about 550 cards a day and that processing more than that number might be harmful to their psychological health. As you might expect, after two weeks they were processing a little over 500 cards a day and reporting stress symptoms when they exceeded that number.
Additional clerks were hired later to operate the same machines, but were told nothing about limits on the productivity rate. After only three days, the new workers were processing over 2,000 cards a day with no ill effects. The original workers believed they could produce only 550 cards, and that is what they did. The new workers had no limited expectations and produced at a much higher rate.