Hawthorne Effect

The Hawthorne Effect is the inclination of people who are the subjects of an experimental study to change or improve the behavior being evaluated only because it is being studied, and not because of changes in the experiment parameters or stimulus.

The Hawthorne Effect refers to the fact that people will modify their behavior simply because they are being observed. The effect gets its name from one of the most famous industrial history experiments that took place at Western Electric’s factory in the Hawthorne suburb of Chicago in the late 1920s and early 1930s. However, subsequent analysis on the effect by University of Chicago economists in 2009 revealed that the original results were likely overstated.

The Hawthorne experiments were originally designed by the National Research Council to study the effect of shop-floor lighting on worker productivity at a telephone parts factory in Hawthorne. However, the researchers were perplexed to find that productivity improved, not just when the lighting was improved, but also when the lighting was diminished. Productivity improved whenever changes were made in other variables such as working hours and rest breaks. The researchers concluded that the workers’ productivity was not being affected by the changes in working conditions, but rather by the fact that someone was concerned enough about their working conditions to conduct an experiment on it.

For many types of research that utilizes human subjects, the Hawthorne effect is an unavoidable bias that researchers must try to take into account when analyzing results. How a subject's awareness of a study might modify their behavior is extremely difficult to quantify. All a researcher can really do is attempt to factor the effect into the research design, which is a tough proposition with no universally agreed-upon methodology. The presence of the Hawthorne Effect renders most social research into a matter that requires experience and human judgment to assess.

As an example of the Hawthorne Effect in action, consider a 1978 study to establish whether cerebellar neurostimulators could mitigate the motor dysfunction of young adults with cerebral palsy, results showed that the Hawthorne Effect adversely affected the findings. Objective testing showed that all of patients reported that their motor functions improved and that they were happy with the treatment.

Quantitative methods, however, showed that there was little improvement, and researchers invoked the Hawthorne Effect as the main factor skewing the results. They believed that the extra attention given to the patients, by the doctors, nurses and therapists, was the reason for the reported improvements in the initial study.