Measuring Driver Visual Distraction with a Peripheral Detection Task

In order to design safe vehicles it is important to be able to evaluate in-vehicle systems to determine how distracting they are for people to use while driving. The Peripheral Detection Task (PDT) is a method for measuring the amount of driver mental workload and visual distraction in road vehicles. It is a secondary task measure where drivers must respond to random targets presented in their peripheral view. As drivers become distracted they respond slower and miss more of the PDT targets. This study aimed to test if the PDT is useful for measuring driver mental workload and visual distraction from in-vehicle information systems in the real roadtraffic environment. Thirteen participants drove on a motorway and country road and performed different tasks (change CD, tune radio and backward counting). The dependent measures were PDT reaction time, hit rate, subjective mental workload and heart rate variability. The PDT reaction time and hit rate measures revealed significant differences between the different tasks. Mean reaction times were slowest for the backward counting task on the country road. The hit rates were best for the baseline driving on both roads and worst for the CD changing task. No significant difference was found between the motorway and the country road for the PDT. It is concluded that the PDT is a good tool for measuring visual distraction and mental workload in a real car. More research is needed to validate the use of the PDT across a wider range of driving and in-vehicle tasks.