Evaluation of the Arousal Level in Motorcar Driving Using Skin Potential Level: Changes in Skin Potential Level under Various Driving Conditions

Abstract

The skin potential level (SPL) on the palmar surface is known to reflect the level of arousal in some behavioral situations. In this paper, this relationship was ascertained in motorcar driving. The SPL was measured for two subjects on ordinary roads under various experimental conditions. The results show that (1) in general, the SPL was kept at high negative levels, and (2) the SPL reduced its electro-negativity when traffic conditions around the motorcar required less tension of the subjects. In the case, the arousal level of the subjects was thought to be low. From these results, it is concluded that the SPL has sufficient sensitivity in detecting the decrease of the arousal level in motorcar driving. In the data processing of the SPL, a range correction was effective in reducing individual differences. The observed maximal reduction of electro-negativity was 80%, in which case the subject complained of serious drowsiness. The SPL was kept at high negative levels when the driver performed an additional light task or conversed with an assistant driver.