Hawthorne Effect: Meaning, Studies & Critiques

What Is the Hawthorne Effect?

The Hawthorne effect is the idea that people change their behavior because they know they are being observed or studied, not because of the change the researchers are testing. It is named after factory experiments at Western Electric’s Hawthorne Works near Chicago, though later analyses suggest those studies show the effect far less clearly than their reputation claims.

The Hawthorne Effect at a Glance

Named after: the Hawthorne Works of the Western Electric Company, in Cicero, Illinois
Studies ran: roughly 1924 to 1932
Key figures: Elton Mayo, Fritz Roethlisberger, and William Dickson (whose 1939 book Management and the Worker is the main report)
Term coined by: Henry Landsberger, in 1958
Main experiments: illumination studies, Relay Assembly Test Room, interview program, Bank Wiring Observation Room
Modern view: the original data are weak evidence for the effect, but participant reactivity is real and is a genuine concern in research design
Close relatives: observer effect, reactivity, demand characteristics, novelty effect

The Hawthorne Studies

In the 1920s, the Hawthorne Works was a huge plant that built telephone equipment for the Bell System. Like many large employers of the period, Western Electric was interested in the “scientific management” ideas associated with Frederick Taylor: the belief that productivity could be raised by finding the optimal physical working conditions, schedules, and incentives.

Over about eight years, a series of studies were carried out at the plant. They are usually told as one story, but they were really several different projects with different researchers, methods, and questions. The best-known involvement came from Elton Mayo, an Australian-born researcher at Harvard Business School, and his colleague Fritz Roethlisberger, working with William Dickson of Western Electric.

The studies are often presented in introductory textbooks as proof that workers become more productive when they receive attention. The actual history is messier, and understanding that mess is a useful lesson in how a finding can harden into folklore.

The Illumination Experiments (1924–1927)

The first studies, begun before Mayo’s involvement and supported by the National Research Council, asked a simple engineering question: does better lighting increase output?

Researchers changed the lighting in some work areas and compared output with areas where lighting stayed the same. The results did not fit a simple story. Output went up in the test groups, but it also went up in the control groups whose lighting had not changed. In some tests, output stayed up even when lighting was reduced, until it became so dim that workers could barely see.

The researchers concluded that lighting was only one of many factors affecting output and that the experiments had been poorly controlled. These studies were never fully published at the time, and the original reports were long thought to be lost. In later retellings, though, they became the most famous part of the Hawthorne story: “productivity rose whatever the researchers did to the lights, so it must have been the attention.”

The Relay Assembly Test Room (1927–1932)

The next and most influential study moved a small group of women who assembled telephone relays into a separate room, where their output could be measured precisely. Over several years, researchers introduced a sequence of changes: different rest breaks, shorter working days, a shorter week, refreshments, and changes in how the group was paid.

Output in the test room generally rose over the course of the study. Strikingly, it did not obviously fall when some of the improvements were taken away. The researchers interpreted this as showing that the physical changes were not the main cause. Instead, they pointed to social factors: the women were in a small, cohesive group, had a friendlier supervisor than on the main floor, were consulted about changes, and knew they were part of a special study.

This interpretation fed directly into the human relations movement in management, which emphasized that workers’ feelings, social relationships, and sense of being valued affect their productivity. That was a genuine and influential shift away from treating workers purely as parts in a machine, and it shaped the later field of organizational psychology.

But several details complicate the story, and they become central in the reanalyses described below. The women were paid under a group incentive scheme based on their small group’s output, which gave them a direct financial reason to work faster. And partway through the study, two of the original workers were removed and replaced.

The Interviews and the Bank Wiring Room

The researchers also ran a large interview program, asking many thousands of employees about their work, supervisors, and grievances. The interviewers found that workers often valued the chance to talk about their concerns, and that complaints frequently reflected broader feelings rather than the literal issue raised. This was early support for the idea that social and emotional factors matter at work.

The final major study, the Bank Wiring Observation Room (1931–1932), observed a group of men wiring switchboard equipment. It is important because its result points in the opposite direction from the popular Hawthorne story. Being observed did not raise output. Instead, the group had its own informal norm about how much work was a fair day’s output, and it enforced that norm through social pressure. Men who worked too fast were labeled “rate-busters,” those who worked too slowly were “chiselers,” and both were teased or pressured back into line.

The Bank Wiring study is really a study of group dynamics and informal norms, closely related to the conformity effects later shown in the Asch experiments. It shows that a group’s own standards can matter more than management’s targets, and more than the presence of observers.

How the Effect Got Its Name

The phrase “Hawthorne effect” did not come from the original researchers. It was coined by the sociologist Henry Landsberger in 1958, in a book reassessing the studies. Over time the phrase came to mean something narrower than anything the original researchers had claimed: a short-term boost in performance caused simply by the awareness of being studied.

That definition has drifted further in everyday use. Today “Hawthorne effect” is used loosely for almost any change in behavior caused by observation, attention, novelty, or participation in research, which makes it hard to test, because different people mean different things by it.

What Later Reanalyses Found

From the 1960s onward, researchers went back to the original records, and their findings substantially undermine the textbook version.

Alex Carey (1967). In a widely cited critique, Carey argued that the Hawthorne conclusions were not supported by the evidence. He pointed out that the studies lacked proper controls, that the small number of workers made the results fragile, and that the explanations involving friendly supervision and attention had been favored over more obvious ones, such as financial incentives and discipline. He highlighted that two of the Relay Assembly Test Room workers had been replaced after being seen as uncooperative, and that one of the replacements was an especially fast and motivated worker who became an informal leader.

Franke and Kaul (1978). Richard Franke and James Kaul ran a statistical reanalysis of the Relay Assembly Test Room data. They concluded that most of the variation in output could be explained by factors other than attention: managerial discipline (including the replacement of the two workers), the economic pressure of the Great Depression, which began during the study and made jobs scarce, and the amount of rest time. Their analysis has itself been debated, but it shifted the burden of proof.

Stephen Jones (1992). Jones reanalyzed the relay data specifically looking for a Hawthorne effect, defined as changes in output linked to changes in experimental attention. He reported little evidence of it.

Levitt and List (2011). The original illumination data were long thought to be lost. Economists Steven Levitt and John List located surviving records and analyzed them. They concluded that the data did not show the dramatic pattern of the popular story, and that earlier descriptions of the illumination experiments had been overstated. They did find some modest, ambiguous evidence consistent with output responding to the experimental changes themselves, but nothing like the striking results the textbooks describe.

Taken together, these analyses suggest that the Hawthorne studies themselves are poor evidence for the Hawthorne effect. Their results can be explained at least as well by incentives, selection of workers, economic conditions, learning over time, and feedback on performance as by the mere fact of being observed.

Is the Hawthorne Effect Real?

The answer depends on what you mean by it.

If you mean the specific story — that the Hawthorne studies proved attention alone raises productivity — the evidence is weak. The original studies had serious design problems, and reanalyses have found more mundane explanations.

If you mean the broader idea that people sometimes behave differently when they know they are being watched or studied, there is good reason to believe it, though the effects vary greatly by setting. A systematic review by Jim McCambridge and colleagues (2014) looked at studies designed to test whether being observed or assessed changes behavior. They found evidence that such “research participation effects” do occur, but the studies were varied, the effects inconsistent, and the conditions under which they appear poorly understood. They suggested moving away from the vague label “Hawthorne effect” toward more precise descriptions of specific mechanisms.

Those mechanisms include:

Social desirability: people present themselves in a good light when they know someone is watching.
Feedback: being measured can tell people how they are doing, which helps them improve.
Novelty: a new procedure, room, or tool can boost motivation temporarily, then fade.
Demand characteristics: participants pick up on what the researchers seem to want and adjust.
Changed incentives: a study often changes rewards, supervision, or conditions at the same time it introduces observation.

Why It Matters for Research Methods

Whatever the truth about Western Electric, the Hawthorne effect has become a standard teaching point in psychology research methods, because it names a real threat to valid conclusions: reactivity, the possibility that the act of studying something changes it.

The main lessons for anyone designing or reading a study:

Use a genuine control group. If both the experimental and control groups know they are being studied and receive the same attention, any effect of observation is equal in both, and the difference between groups reflects the intervention. The illumination experiments failed partly because the comparison groups were not treated equivalently.
Blind where possible. In single-blind and double-blind designs, participants (and, ideally, researchers) do not know who is in which condition. This guards against both participant expectations and experimenter expectancy effects, discussed in our article on the self-fulfilling prophecy.
Use unobtrusive measures. Records, archival data, or measures participants do not notice reduce reactivity, though they raise their own ethical questions about consent.
Allow for habituation. Observers who stay long enough tend to fade into the background. Researchers using observation often discard early data for this reason.
Separate the components. If an intervention bundles new incentives, new supervision, and observation together, the study cannot say which one mattered.
Watch for regression and time trends. Performance often improves over time with practice anyway; a study without a comparison group can mistake learning for an effect of the intervention.

The Hawthorne story is also a lesson in scientific skepticism. A finding repeated in textbooks for decades can rest on thinner evidence than its fame suggests. The same pattern appears with other famous studies, such as the Stanford prison experiment, whose conclusions have also been heavily revised.

Examples Outside the Factory

Hand hygiene in hospitals. Studies of hand-washing often find that staff wash their hands more often when they know an auditor is watching than when compliance is measured unobtrusively. This makes observed compliance rates an overestimate.
Clinical trials. Participants in the control arm of a trial often improve too, partly because they receive regular check-ups and attention, and partly because of placebo effects and natural recovery. This is why trials compare treatment against a control that receives the same contact.
Classroom observation. Teachers and students may behave differently when an inspector is in the room, which limits what a single observed lesson can show.
Fitness trackers and diaries. Simply recording your food intake or steps can change behavior, partly through feedback and partly through awareness. This is sometimes deliberately used in behavior change programs.
Workplace monitoring. Employees may work differently when they know their activity is logged. Whether this is “more productive” depends on what is measured; people tend to optimize for the metric rather than the underlying goal.

Frequently Asked Questions

What is the Hawthorne effect in simple terms?

It is the idea that people change how they behave when they know they are being watched or studied. For example, workers might work harder during a study simply because they are getting attention, not because of the change the researchers are testing.

What did the Hawthorne studies find?

The studies at Western Electric’s Hawthorne Works (about 1924 to 1932) reported that output rose in several experiments regardless of changes to lighting or rest breaks, which researchers attributed to social factors. A later study found that work groups set and enforced their own output norms. Reanalyses have since questioned whether the data support the popular interpretation.

Who discovered the Hawthorne effect?

The studies are most associated with Elton Mayo, Fritz Roethlisberger, and William Dickson, but none of them used the term. The sociologist Henry Landsberger coined the phrase “Hawthorne effect” in 1958 when reviewing the studies.

Is the Hawthorne effect real?

Partly. Reanalyses of the original data suggest the Hawthorne studies themselves are weak evidence, since incentives, worker replacement, and economic conditions may explain their results. More recent research does suggest that being observed or assessed can change behavior in some situations, but the effects are inconsistent and depend on the setting.

How do researchers control for the Hawthorne effect?

Mainly by using control groups that receive the same attention and observation as the experimental group, so any effect of being studied is equal in both. Blinding, unobtrusive measures, and allowing time for participants to get used to observers also help.

What is the difference between the Hawthorne effect and the placebo effect?

The placebo effect is improvement caused by a person’s belief that they are receiving an effective treatment. The Hawthorne effect is a change caused by awareness of being observed or studied. Both are reasons why studies need well-designed control groups, and they can occur together.

The Hawthorne Effect: Definition, Original Studies, and Criticisms