Effects of Heat on Wireless Operators

When the Royal Navy asked the Medical Research Council to enquire into the effects ofheat on human beings, the resulting investigations came under two general headings. The first was the question whether high atmospheric temperatures affected some forms of human activity more than others. An answer to this question was needed to determine which compartments in ships should have priority in the allocation of air-conditioning equipment. The second main aim of the research was to discover the extent of the overlap between the effects of the heat on the body as assessed by physiological techniques and the effects of heat on human performance as measured by psychological experiment. Answers to this second question might indicate how far it was safe to use simple measures of bodily functions to predict the presence of performance deterioration. The first question has entailed studies of the effects of heat on a wide variety of real-life human activities, all of which are vital for the fighting efficiency of the modern warship. Actual human performance has been measured with tests demanding either hard thinking or heavy physical effort. Sometimes, however, a different line of approach has been tried with the volunteer experimental subjects who were usually Naval ratings; instead of these men having too much to do, their patience has been tried by giving them too little to do, as, for example, in jobs imitating dull and monotonous look-out duties. The accuracy of their watchkeeping showed whether they could remain wide awake and alert under these circumstances. Conversely, the ability to sleep soundly with the minimum of restlessness has also been studied at different room temperatures. But there is no great difference between the effects of heat on all these various forms of human activity, and this paper can therefore be taken as representative of the bulk of the evidence now available-see also Houghten (1942), and Weiner and Hutchinson (1945). Specifically to this study, the problems relating to the first main question were: 1. Do hot and moist atmospheres impair the accuracy with which trained wireless telegraph operators can write down morse messages heard over their headphones? 2. If any such deterioration is found, how far may the atmospheric temperature be allowed to rise (above the lowest temperature readily obtainable with air-conditioning plant in tropical waters) before this deterioration becomes statistically definite? The second general question of the correlation between bodily changes and human performance is clearly a complex matter and here the research aims have been limited to an analysis of the relationship between rectal temperature and working efficiency since rectal temperature is one of the most widely used physiological measures in hot-room investigations. The specific problems arising from this second main question were: 3. Does increased room temperature lead to a rise in body temperature with sedentary work of this nature? 4. Are the performance test scores on this wireless telegraphy reception test statistically related to the rectal temperature readings? 5. If so, is there any evidence that a rise in body temperature causes deterioration in ability on this wireless telegraphy test?