伊藤 一也

How do drivers cope with the attentional workload of in-vehicle information technology? In the present study, we propose a new psychophysiological measure for assessing drivers' attention: eye-fixation-related potential (EFRP). EFRP is a kind of event-related brain potential measurable at the eye-movement situation that reflects how closely observers examine visual information at the eye-fixated position. In the experiment, the effects of verbal working memory load and spatial working memory load during simulated driving were examined by measuring the number of saccadic eye-movements and EFRP as the indices of drivers' attention. The results showed that the spatial working memory load affected both the number of saccadic eye-movements and the amplitude of the P100 component of EFRP, whereas the verbal working memory load affected only the number of saccadic eye-movements. This implies that drivers can perform time-sharing processing between driving and the verbal working memory task, but the decline of accuracy of visual processing during driving is inescapable when the spatial working memory load is given. The present study suggests that EFRP can provide a new index of drivers' attention, other than saccadic eye-movements.

For reasons of convenience and safety, it is important to assess the drivers’ workload while using in-vehicle devices. Recently, we proposed a new psycho-physiological measure for assessing drivers’ attention: eye-fixation-related-potential (EFRP). EFRP is a kind of event-related-brain potential (it were made of brain waves (EEG) and the electrooculographic (EOG)) measurable in normal driving. In the present study, we manipulated the cars’ navigation system and measured the affect on drivers attention by measuring EFRPs. There were two tasks: a voice-activated task (the drivers manipulated the navigation system via voice) and a manual task (the drivers manipulated the navigation system by hand). The results showed that the amplitude of P100 component of EFRP during simulated and actual driving decreased greatly with the manual task when compared to the voice-activated task. This finding implies that drivers can manipulate in-vehicle systems more safely by the voice-activated devices than the manual devices.

On-board voice-interaction systems such as a voice-activated system or a text -to-speech (TTS) system enable drivers to operate devices or to obtain desired information without relying on visual processes. These systems are aimed to reduce the driver's workload, but there is a concern about their possible effect on mental distraction. This paper describes driving simulator tests that were conducted to examine the potential influence of such systems on driver's mental distraction. The results obtained for all of the indices show that the mental distraction level when operating a voice-activated system is significantly lower than that of a traditional manually operated system. Copyright © 2004 SAE International.