Productivity and fatigue

For a long time in the history of the productivity study, the effects of environmental factors onlyon the performance had been focused. However, previous studies on the impact of theenvironment upon performance of mental tasks generally conclude that productivity research issomewhat confusing because the results are sometimes conflicting. In the controlled chamber,subjects may be highly motivated for a short time period, so it is very difficult to find thedifference of performances. In this paper, we introduce a second parameter : fatigue. Threesubjective experiments are reported. To evaluate fatigue is a key to evaluate productivity.