Shedding light on the Hawthorne Effect

If you’ve been looking at motivation in the workplace this year, chances are you’ve talked about Elton Mayo, who is best remembered for writing about experiments done in a telephone parts factory in the 1920s and 30s. The results of the Hawthorne study lead to an extremely influential idea: that the very act of being experimented upon changes subjects’ behaviour. However, new analysis of the experimental data suggests this may be the wrong conclusion.

The original idea of the investigation was to learn how shop-floor lighting affected workers’ productivity. The Economist tells the story nicely: according to accounts of the experiments, their hourly output rose when lighting was increased, but also when it was dimmed. It did not matter what was done; so long as something was changed, productivity rose. An awareness that they were being experimented upon seemed to be enough to alter workers’ behaviour by itself.

But fresh analysis (by the hip Freakonomics people) of the data, long thought to be lost, found no systematic evidence that levels of productivity in the factory rose whenever changes in lighting were implemented. According to the article:

“Instead, the way in which 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.

Another of the original observations was that output fell when the trials ceased, suggesting that the act of experimentation caused increased productivity. But experimentation stopped in the summer, and it turns out from the records of production after the experiments that output tended to fall in the summer anyway. Perhaps workers were just hot”.

So perhaps the truth is more complex: pass over to Maslow, McGregor, Herzberg and the rest to offer alternative, more sophisticated explanations of the motivation to work.