Emotional alterations under attentional loads during sustained heat exposure

The globally escalating heatwaves are threatening people’s well-being by imposing more intensive and longer heat exposures. The emotion is one important aspect frequently affected by heat exposure, especially under mental workload. However, the gap always exists that no quantitative approach/model could facilitate the emotional evaluation. To address this gap, a 150-min heat exposure was conducted at 31℃, 33℃, and 35 ℃, with the relative humidity of 50 ± 3%. The within-subject design was followed among 14 participants. During the heat exposure, four kinds of attentional tasks were administered continuously to simulate the mental workloads, and the skin temperature was continuously recorded with the 4-point method. Besides, the Brunel Mood Scale (BRUMS) was completed to acquire the emotional changes. Results showed that ‘depression’ and ‘fatigue’ subscale of the BRUMS increased with both the environmental temperature and exposure time, which indicated that the emotion had been negatively affected. Meanwhile, the mean skin temperature rose with the temperature and exposure time by almost 1.2 ℃. Based on that, correlation analysis was conducted. Results indicated that the emotion ‘depression’ was significantly correlated with mean skin temperature, with the Spearman’s ρ of 0.65 (p<0.05). Thereafter, a linear regression was carried out considering the effective size, and a quantitative model based on the mean skin temperature for the quantitative evaluation of emotions under cognitive-demanding scenarios and in the heat was obtained. Findings of this study provided a potential solution for the objective emotion evaluation of mental-demanding workers who have to work in the heat.