Productivity rose whether the researchers brightened the lights or dimmed them.
In November 1924, researchers at the Hawthorne Works of the Western Electric Company in Cicero, Illinois, began a series of illumination experiments sponsored by the National Research Council.1 The plant employed more than 40,000 workers who assembled telephones, cables, and communications equipment for AT&T. The purpose was straightforward: measure how changes in lighting affected worker productivity.
The results defied expectation. When the lights were brightened, output rose. When the lights were dimmed, output rose again. Even when illumination was reduced to near-darkness, productivity continued to climb.2
In 1927, George Pennock, a superintendent at the plant, met Elton Mayo, an Australian psychologist at Harvard Business School, at a meeting of the National Industrial Conference Board.3 Pennock invited Mayo to investigate the puzzling results. Mayo arrived at the Hawthorne Works with a team that included Fritz Roethlisberger, a sociologist, and William Lloyd Warner, a social anthropologist.
From 1928 to 1930, the team conducted more than 20,000 interviews with workers.4 They discovered that employees were motivated far more by social relationships and a sense of being valued than by physical working conditions or pay alone.
A separate experiment placed a group of fourteen men who assembled telephone switching equipment under close observation from 1931 to 1932.5 Researchers discovered that the men had developed informal social groups with unwritten rules about acceptable production rates. Workers deliberately limited their output, fearing that higher productivity might lead the company to raise quotas or eliminate jobs. The finding undermined Frederick Winslow Taylor's premise that workers were purely rational agents motivated by money.
In 1933, Mayo published The Human Problems of an Industrial Civilization. Roethlisberger and William Dickson followed in 1939 with Management and the Worker, a comprehensive summary of the experiments.4 The Hawthorne studies became the foundation of the human relations movement in management theory, and the phrase "Hawthorne effect," coined in 1953 by John R.P. French, entered common usage as a term for the phenomenon in which people modify their behavior when they know they are being observed.1 Western Electric's Hawthorne plant operated from 1905 until 1983.