“…During recent years, it has been demonstrated experimentally that a number of physical stressors affect human performance, e.g. heat, noise, vibration, drugs, and sleep loss (Cannon, Drucker & Kessler, 1964;Wilkinson, 1969). Likewise, it is a fact that under certain conditions different kinds of psychological stress impair performance: failure, distraction, heavy workload, and threat of physical harm (Lazarus, Deese & Osler, 1952).…”