At the start the experiments concentrated on improvements to lighting. Productivity did improve, but it also improved when the lighting levels were lowered. This odd result was repeated in experiments which looked at pay, incentives, rest periods, hours of work, and supervision. Mayo advanced two theories. He firstly suggested that the very fact of being involved in an experiment encouraged the workers to be more productive. It created interest and involvement in their repetitive work, and their managers began taking an interest in how they felt. Mayo's second theory was that social interaction had a critical effect on motivation because the experiment meant bringing workers together in teams with a positive relationship with a supervisor,

In any event it seemed the workers simply appreciated the change the experiments brought about, felt more valued and generally happier and thus their performance improved.

Mayo's research has come in for much criticism over the years. Many claim that it was the incentives that the workers were offered to participate that really caused the increase in productivity. Nevertheless his studies shifted the science of management from Taylor's engineering approach to a social sciences approach. Almost at once, management became a question of considering motivation, leadership and group dynamics. The human relations approach was born. Managers still had to design jobs, create a reward structure and select and train the employees but were now also responsible for motivating, communicating, leading and generally monitoring the social setting in which work took place. A change from task focus to people focus which even today many managers find difficult to make.

Had we understood coaching better at the time of the Hawthorne experiments the transition from scientific management would have been easier to make, for coaching is concerned with both tasks and people. It is performance focused, with a focus on taking action, make changes and create mobility, but is also person centred in acknowledging that - in the end - it is people that take action, make changes and become mobile. Creating desire for coaching requires us to stress the potential for finding out about oneself as well as finding ways to improve the way that work is undertaken.

The phenomenon revealed by Mayo's experiments has subsequently been labeled the Hawthorne effect. It has become the scourge of researchers who would prefer to be able to ignore or isolate its effects and explains why much modern research into Human Resource Development (HRD) is at pains to ignore terms such as 'proof', 'fact' and 'cause'. But the Hawthorne effect can be a great asset to managers that coach who - provided their intentions are sincere - can be assured that simply taking a keen interest in the human side of business and work will create a more positive climate and provide the basis for improved results.