The Fragile Hawthorne Effect

The Hawthorne effect is often brought up in industrial psychology. It was brought up when constructing industrial experiments and simulations where the behavior of people was involved. As it was presented, an experiment introduced better lighting in an industrial environment. Productivity increased. It was later discovered that any change in lighting in the environment, more light or less, increased productivity. The conclusion being that paying attention to the workers at all changed their productivity. Even when I was introduced to it we were told that this should be seen as a principle of caution and not some deep result. As an experts-can-be-wrong story it has survived a long time.

Now Steven D. Levitt and John List, of the NY Times Freakonomics blog say they have looked at the original data and find it does not support the conclusion that is primarily described as the 'Hawthorne effect'. A more complete write-up in the Economist.

' ... It turns out that idiosyncrasies in the way the experiments were conducted may have led to misleading interpretations of what happened. For example, lighting was always changed on a Sunday, when the plant was closed. When it reopened on Monday, output duly rose compared with Saturday, the last working day before the change, and continued to rise for the next couple of days. But a comparison with data for weeks when there was no experimentation showed that output always went up on Mondays. Workers tended to beaver away for the first few days of the working week in any case, before hitting a plateau and then slackening off ... '

Points to classic issues of data collections and external influences. You still have to consider the effect of observation on real people.