Most every student of psychology (and many other disciplines) has heard of the legendary Hawthorne effect. Steve Levitt (of Freakonomics fame) and John List have just published an article on the website of the National Bureau of Economic Research in which they reveal that they have discovered the thought-to-be-long-lost data from the original Hawthorne experiments of the 1920s. Contrary, however, to the widespread belief in the pervasiveness of the effect, Levitt and List say that there is very little consistent evidence of such an effect in the original data.

The article itself is available on-line for a charge of $5 (and giving up some information about yourself to some on-line company). However, Peter Klein of the blog “Organizations and Markets” has reprinted to following snippet:

The “Hawthorne effect,” a concept familiar to all students of social science, has had a profound influence both on the direction and design of research over the past 75 years. The Hawthorne effect is named after a landmark set of studies conducted at the Hawthorne plant in the 1920s. The first and most influential of these studies is known as the “Illumination Experiment.” Both academics and popular writers commonly summarize the results as showing that every change in light, even those that made the room dimmer, had the effect of increasing productivity. The data from the illumination experiments, however, were never formally analyzed and were thought to have been destroyed. Our research has uncovered these data. We find that existing descriptions of supposedly remarkable data patterns prove to be entirely fictional. There are, however, hints of more subtle manifestations of a Hawthorne effect in the original data.

Thanks to Thomas Leahey (of Virginia Commonwealth U.) for putting me on to this article.