Effects of work in a hot environment on repeated performances of multiple types of simple mental tasks

Rates of unsafe behavior and accidents in industrial settings have been shown to increase concomitantly with elevated work-rates and in environments above 24 °C WBGT, and when core temperature exceeds 38 °C. While multiple variables may play a role in the increase in risky behavior, a decrease in cognitive function could be an underlying contributor. Past research has produced conflicting results in predicting the relationship of physical activity and heat exposure to changes in cognitive function. The present study examined the changes in performance of three different simple mental task tests after a simulated heavy workload task (∼450 kcal/h) in a hot humid environment (30 °C WBGT). The treatment was repeated, with work time slightly extended and cognitive tests were repeated to test the stability of the cognitive measures. Male participants (n = 10) completed two trials (one with a novel cooling vest device and work duration of 98.3 ± 39.5 min, and without cooling with a duration of 73.5 ± 26.7 min) and were given short-term memory, arithmetic, and reaction time/tracking tests before and after each trial (termination criterion was a core temperature of 38.7 °C). Although some individuals displayed practical significant changes, both positive and negative, there were no significant differences (p > 0.05) found between the mean pre–post scores for any of the three tests on either trial. Comparisons of post–post scores for all three tests showed lower correlation than pre–pre test comparisons suggesting the heat and physical activity did alter cognitive performance. The arithmetic style test appeared to be the most suitable and reliable of the three tests to detect changes in cognitive function.Relevance to industryThe results of this study are in agreement with past research suggesting that alterations in cognitive function for individuals exposed to physical activity in a hot environment may increase, decrease or change very little. While mental processing alterations may widely vary after heat exposure between individuals, a repeated application of an arithmetic style test could help predict workers who will be most negatively affected. Recognition of these individuals could allow supervisors to more effectively manage workers and possibly make the work environment safer in instances where a mental mistake may result in an accident. Math is a universal and well rehearsed skill that is unlikely to change over short periods of time. The materials needed to conduct a mathematical skill tests are minimal in comparison to other methods, appear to be repeatable within subjects and are both time and cost efficient.