To investigate the effects of verbal assessment of subjective driver state on objective indicators of vigilance state during a monotonous daytime drive, a real road driving study was conducted. During a 4-h drive participants' subjective state (sleepiness, inattention, monotony) was assessed every 20 min by an investigator accompanying the drive. The assessment procedure consisted of roughly 1 min of verbal interaction. Physiological indicators (EEG alpha spindle rate, blink duration, heart rate) revealed a significant improvement of vigilance state during the communication episode as compared to a pre-assessment baseline. The activation persisted for up to 2 min following the end of the verbal interaction. Reaction times supported these findings by indicating a significant decrease after the communication. The P3 amplitude of the auditory event-related potential did not show any consistent results. It can be concluded that a short verbal assessment has positive effects on drivers' vigilance state. However, these effects persist only for a very limited time. The implications of these findings for the frequency of verbal assessment during experimental studies and for the use of verbal communication as a fatigue countermeasure are discussed. Keywords: Driver distraction;
", language="en", issn="1369-8478", doi="10.1016/j.trf.2011.01.005", url="http://dx.doi.org/10.1016/j.trf.2011.01.005" }