Effects of Vehicle Air Temperature on Drivers’ Cognitive Abilities Based on EEG

Vehicle air temperature affects drivers’ physiology, psychology, and cognitive abilities. However, the effects are difficult to quantify, especially for jobs related to driving tasks. In this research, 10 male subjects were directly exposed to four different vehicle air temperatures of 20, 23, 26, and 30 °C for 160 min. They were asked to perform cognitive tasks and subjective questionnaires, and 16 channels of EEG signals were monitored in a vehicle cabin. Based on the assessment of the EEG characteristics, the impacts of vehicle air temperature on cognitive abilities and EEG were investigated. The results showed that the cognitive ability of drivers decreased with the rising of the ambient temperature. The subjective questionnaire scores for thermal sensation, thermal comfort and brain load increased as ambient temperature rose; meanwhile, the scores for environmental acceptance, job satisfaction and willingness to work declined. As the ambient temperature rose, the normalized power of θ activity and α activity elevated, and the vigilance and frontal EEG asymmetry decreased. At 20 °C, the completion time of cognitive ability test was the shortest, the number of errors was the smallest, and the drivers could maintain high cognitive ability. At this time, the β activity component of the EEG signal increased, and the level of alertness (AL) and prefrontal asymmetry (FEA) also increased. At 23 °C, drivers’ subjective thermal comfort reached its peak: the EEG wavelet entropy values of the two segments before and after the experiment were the largest, and the wavelet entropy difference was also the largest. A suitable vehicle air temperature aroused β activity and motivation, increased driver alertness and thus enhanced cognitive performance. Therefore, to achieve high cognitive ability and thermal comfort, the vehicle air temperature should be maintained between 20 °C and 23 °C. The research results can provide a reference for the design standards of vehicle air temperature and improve the safety of driving.