Between 1924 and 1933, research teams from Harvard University conducted field studies on worker productivity at the Western Electric Hawthorne plant near Chicago, one of the most advanced manufacturing facilities that employed 29,000 workers to produce telephones and telecommunications equipment for AT&T.
The experiments initially concentrated on the relationship between productivity and work place lighting. Groups of six workers were removed from the production line to perform their normal work in an enclosed space where researchers changed the intensity of the electric lighting. To the researchers' surprise, both more and less light created higher productivity levels.
Sociologist Mayo joined the experiments in early 1928 and realised that the workers chosen for the experiment were accorded higher status by their co-workers. The increased performance was due to their increased motivation. Productivity was related to social effects, not the level of lightning. Mayo called such social behaviour the 'Hawthorne Effect'.
Mayo expanded the research to look at pay and incentives, rest periods, hours of work, supervision and work pace. Again, he recorded remarkable increases that had little relation to these variables.
Mayo concluded that the workplace was above all, a social system of interdependent actors in which workers are influenced more by the social demands of the work place, by their need for recognition, security and a sense of belonging, than by their physical working environment.
He also concluded that:
Years after the study, it was discovered that the workers' "social interaction" in the experiment had surpassed Mayo's analysis. The participants decided to purposefully derail the experiments by manipulating their production levels.
Observers are always a factor in their research, no matter how neutral their position. This influence on the group must be acknowledged during an analysis or implementation activity. The 'Hawthorne Effect' led to the development of 'Action Research', a methodology that assumed that understanding of situations and change occur simultaneously.
Informal groups exert strong social controls over the work habits and attitudes of the individual employee. The strengthening of informal relations among organisation members, the development of 'hero' teams as well as the fostering of cultural aspects are important design factors that increase employees' feelings of belonging. However, informal groups can also be detrimental, particularly, when group norms prevent new ways of working.
The mechanically oriented Scientific Management was the dominant management theory at the time of the Hawthorne experiments. The Hawthorne studies showed that organisations are not just technical, economic systems, but social systems. Productivity gains are achieved not only by a more efficient layout of a production line, but also by employees' mental states. The Hawthorne experiments led to the School of Human Relations.
Mayo's work focused on the social end of the continuum to offset the dominance of Scientific Management theory. Since Mayo did not try to integrate his conclusions with Scientific Management, his recommendations remained uni-dimensional.
Mayo's interpretation that employees derive greater motivation from informal groups does not rule out other causes such as learning, expertise and reflection, all of which remained unexamined premises independent of Mayo's investigated interventions.
Empirical proof for the Hawthorne Effect was at best weak, reanalysis of the data showed (Stephen R. G. Jones, Was There a Hawthorne Effect, The American Journal of Sociology, 1998)