Hawthorne effect
The Hawthorne effect is the change in people’s behaviour that happens because they know they are being watched or studied, rather than because of anything the observer actually changed.
- 1 min read
- 6 linked ideas
Why does the hawthorne effect happen?
Being observed alters what feels at stake. People who know they are part of a study may work harder, follow rules more closely, or try to give researchers the result they seem to want. The extra attention, the novelty of the situation and simple awareness of being measured can all shift behaviour. Because these influences arrive alongside any real intervention, a study without a comparison group cannot tell whether an improvement came from the change being tested or from the act of watching.
What does the hawthorne effect look like in real life?
- Staff washing their hands more often in weeks when an auditor is visibly checking compliance.
- A pilot scheme that looks successful while it is closely monitored, then fades once attention moves on.
- Patients in a trial keeping better health habits simply because they are filling in diaries and attending check-ups.
- The name comes from studies at the Hawthorne Works electrical plant near Chicago in the 1920s and 1930s, whose famous lighting results later reanalyses have questioned.
How do you counter the hawthorne effect?
- Use a control group that receives the same attention and measurement but not the intervention.
- Measure over a longer period so any novelty-driven boost has time to wear off.
- Where it is ethical, rely on unobtrusive data (routine records) instead of visible observation.
Frequently asked
- What is the Hawthorne effect in simple terms?
- People behave differently when they know someone is watching. If you study a group openly, part of any improvement you see may come from their awareness of being studied rather than from the thing you changed.
- Is the Hawthorne effect real?
- Its classic origin story is disputed. Levitt and List reanalysed surviving data from the original lighting experiments and found little support for the dramatic effect usually described. A 2014 systematic review concluded that observation can change behaviour, but the size and conditions vary widely.
- What is an example of the Hawthorne effect at work?
- A manager announces that productivity will be tracked closely for a month. Output rises during that month even though nothing about the tools or process has changed, then drifts back once the tracking ends.
- How do researchers avoid the Hawthorne effect?
- They compare against a control group that is observed in the same way, use blinding where possible, collect data unobtrusively, and run studies long enough for the novelty of being watched to fade.
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Cite this page
ReadGlobe. (2026). Hawthorne effect. https://readglobe.com/bias/hawthorne-effect/
"Hawthorne effect." ReadGlobe, 24 Oct. 2026, readglobe.com/bias/hawthorne-effect/.
Editorial synthesis © ReadGlobe 2026, drawing on Kahneman’s Thinking, Fast and Slow, the Tversky–Kahneman research program, and the primary cognitive-science literature. · Last reviewed 2026-10-24.