In driving research there is quite some focus on distraction of in-vehicle systems, like using navigation systems or mobile telephones. However is is not so clear whether day-dreaming or task unrelated thoughts have the same negative effects on traffic safety. In cooperation with DGP, AVV, SWOV, Achmea and DGTL, TNO conducted a study to analyse these effects. Three groups of participants made two drives on a motorway in the TNO driving simulator. Group 1 did not perform any secondary task, group 2 performed a `thinking and reasoning' task during specific parts of the drive and group 3 performed a `listening and remembering' task during the same parts of the drives as in group 2. Due to the explorative nature of this study, various measures were taken, such as behavioural measures, physiological measures and a subjective indication of the amount of attention focused on the driving task. The dependent measures that lead to results were the deviation from the speed limit, driving speed, standard deviation of the speed, number of lane changes, maximum deceleration, mean deceleration, Steering Reversal Rate, number of glances in the mirrors, heart rate variability (high frequency) and the subjective measure. In some cases, there was only an effect of the `listening and remembering' task but in other cases there were also effects for the `thinking and reasoning' task. In those cases, the results pointed to the same (negative) effects as the `listening and remembering' task. Participants also indicated that they had the feeling they paid less attention to the driving task during the secondary tasks, so also during the `thinking and reasoning' task. During driving, even internal distraction (thinking about non-driving task related issues) does have effects on performance, with the effects being somewhat similar (although often less severe) to the (negative) effects of in-vehicle tasks. In a real setting, the effects are expected to be even larger if a driver spontaneously starts day dreaming. Due to the experimental set-up, the participants were aware of the actual start of the `thinking and reasoning' task, having the possibility to compensate (for instance by actively looking around). Despite the fact that the thinking and reasoning task was self-paced in a sense (one could somewhat vary amount of involvement) effects were still present. (Author/publisher)
Samenvatting