Effects of hot-humid exposure on human cognitive performance under sustained multi-tasks

Compromised cognitive performances under hot and humid environment have been widely reported in recent years, as the extreme climate events come more frequently and intensively. In order to evaluate the cognitive performance under hot-humid exposure, the skin temperature, core temperature and the heart rate of 14 right-handed male participants were measured when they were conducting 5 different kinds of cognitive tasks under hot-humid environments at 32, 35, 38, 41 °C and RH 70 %. Each session consisted of these 5 tasks with different orders followed the Latin Square Design. And the session was repeated in the whole experiment till each participant refused to continue. Results showed that the mean skin temperature (Tmsk) increased during the hot-humid exposures, which was attributed to the air temperatures and the exposure time. Furthermore, the mean accuracy and response time of these tasks were negatively related with each other. A U-shape relation between the Tmsk and mean accuracies was observed, while an Inverted-U relation between the Tmsk and the mean response time was detected. Finally, a 4th order-function paradigm was acquired between the Tmsk and the relative cognitive performance (RCP). In terms of the results, the small Tmsk range from 36.0 °C to 37.25 °C was presented, within which the stable RCP were observed, while out of which the RCP deteriorated. The findings provided a potential solution for the evaluation of the cognitive performance under hot-humid exposures.