The Hawthorne effect says people change their behavior when they know they are being watched, and it is taught as gospel in management and psychology classes. This episode returns to the Western Electric Hawthorne Works in Cicero, Illinois, where illumination experiments from 1924 to 1927 found output rising in both the brighter test room and the unchanged control room, and still rising as lights were dimmed, until the workers could no longer see. From 1927, Elton Mayo’s Relay Assembly Test Room moved six women into a quiet room with breaks, snacks, and shorter days, and their output hit an all time high even after the perks were taken away.

Then the bank wiring room study of the early 1930s, with Mayo and W. Lloyd Warner, offered 14 men piece rate pay, and output fell. In the Depression, the men suspected higher output would bring lower rates or layoffs and enforced their own quotas. Later critics were harsh: Richard Nisbett called the effect a glorified anecdote, Harry Braverman saw class conflict, and in 2011 Steven Levitt and John List found the original lighting data on microfilm at the University of Wisconsin in Milwaukee and saw only weak evidence. The idea now lives on as the trial effect in medicine.

• Costco’s extra $2 an hour during COVID-19 as a contrast in pay that worked
• A Hawthorne interviewing program that spoke with 20,000 workers about group dynamics
• J.G. Adair’s demand effect, where subjects act out what researchers seem to want
• H.M. Parsons’ argument that the clicking relay counter gave the women real time feedback
• Nate Breznau’s secondary observer effect, in which 29 teams reached different conclusions from one soccer red card dataset