Hot Humid Environment: its Effect on the Performance of a Motor Co-ordination Test

It is well known that prolonged stay in a hot humid environment, especially when the temperature of the body is raised, is accompanied by feelings of lassitude and irritability. In such conditions, as simulated in the laboratory, one is often aware also of a tendency to forgetfulness, to some ' slowing' of one's movements and there seems to be an enhanced liability to breakage of glassware and thermometers. Many observers ofexperiments in hot conditions have testified to such reactions. During the course of some experiments on acclimatization to heat we had the opportunity of making a number of observations on the ' psychomotor' performance of resting and working subjects exposed to 'effective' temperatures above 900 F.* The results presented in this paper are regarded as preliminary only and of limited application to everyday activity in hot climates or occupations. However, as the findings seem sufficiently consistent we consider they support the belief that a measureable impairment of manual dexterity or co-ordination occurs at high environmental temperatures.