Hawthorne Effect
People change their behavior when they know they are being observed.
Origin & History
The term comes from a series of experiments at Western Electric's Hawthorne Works factory near Chicago in the 1920s–30s. Researchers studying the effect of lighting on productivity found that output improved regardless of whether they increased or decreased the light — and regardless of almost any other change they introduced. Elton Mayo later concluded that the workers were responding to the attention itself, not to any specific variable. The experiments are considered a founding moment in organizational psychology.
Real-World Examples
Researchers at Hawthorne Works changed lighting, break schedules, workstation arrangements — and productivity improved with each change, regardless of direction. Workers were motivated by being studied, not by any specific condition.
Patients in the placebo arm of drug trials often show measurable improvement simply from the attention of being enrolled in a study — even when receiving no active treatment. This is why double-blind trials are essential.
Employees whose work is being formally reviewed — for pay decisions, promotions, or audits — consistently perform above their normal baseline during the review period, then revert afterward.
Why It Matters
The Hawthorne Effect reveals that measurement changes what is being measured. This is a fundamental challenge for any study of human behavior: the act of observation is itself an intervention. For managers, it suggests that regular, visible attention to a team's work can improve performance — not because of what you observe, but because observing signals that you care. For researchers, it demands controls to isolate the effect of attention from the effect of the intervention being studied.
Related Laws
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When people know they are being watched, they change their behavior — usually by working harder or performing better — regardless of what specific change is being observed.
From experiments at Western Electric's Hawthorne Works factory in the 1920s–30s, where researchers found productivity improved with almost any change because workers knew they were being studied.
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