The purpose of this report was to investigate how drivers' subjectively experienced trust and acceptance of automated in-vehicle systems which are associated with their measurable driving performance. Data from two previously performed driving simulator studies of the integration with Adaptive Cruise Control (ACC) systems were studied. It was hypothesised that a lower acceptance of the ACC system was associated with a more aggressive driving style, for example higher driving speed and a shorter distance to the vehicle ahead. It was also hypothesised that higher trust in the ACC was associated with later intervention in critical situations. It was shown that lower acceptance of an automatic ACC was associated with a more aggressive driving style in situations where the drivers caught up with slower vehicles. It was also shown that trust in an automatic ACC was associated with later intervention when the drivers mistakenly thought that the ACC would brake. When a telephone task was performed together with driving with the automatic ACC, the driving measures were more homogeneously distributed. This implies that when drivers are more mentally loaded by a competing task, they are more inclined to hand over control of the driving task to an automatic system. (Author/publisher)
Abstract