In the early 1920s Chicago’s Western Electric Hawthorne Works employed 12,000 workers. The plant was a primary manufacturer of telephones, and in 1924 the company provided a site to cooperate with the NRC on a series of test room studies to determine the relationship between illumination and worker efficiency. The basic idea was to vary and record levels of illumination in a test room with the expectation that as lighting was increased, productivity would too. In another test room, illumination was decreased, with the correlating expectation that efficiency would decrease.
The electric power industry provided an additional impetus for these tests, hoping to encourage industries to use artificial lighting in place of natural light. The Illuminating Engineering Society’s Committee on Research also supported the tests and cooperated with the NRC. From the fall of 1924 to the spring of 1927, three series of tests were conducted and carefully monitored. Three departments at the Hawthorne plant were involve delay assembling, coil winding, and inspection. Workers were notified of the tests in order to attempt to control interference from human factors.
When production increased in each test period, researchers looked to other factors such as increased supervision and a sense of competition that developed between the test and control groups. But the one conclusion the impressive team of industrial specialists and academics discovered was the lack of a consistent correlation between lighting levels and product output. No further tests were planned originally, but researchers were surprised at the unanticipated results. NRC representatives and the engineers involved drew several conclusions. First, illumination was one factor in output but not the most important.
More important to the tests was the realization there was not a simple answer to the issue of illumination and worker productivity and that other factors that were not controlled presented a problem with the test results he issue of human factors. In retrospect, researchers from the NRC and the Illuminating Engineering Society (which together formed the Committee on Industrial Lighting) stated they were not surprised by the test results. They even predicted that other factors would affect the results, but their mandate was to isolate other variables, and the Hawthorne studies continued.