Assessment of the occlusion technique as a means for evaluating the distraction potential of driver support systems

Driver distraction is a safety-critical issue that has been bought to greater public attention with the recent developments of more advanced driver support systems (DSS), e.g. navigation systems. Such systems have the potential to distract drivers significantly from the primary task of controlling their vehicle, potentially resulting in an accident. DSS developers need to be able to assess distraction potential in the early stages of design. In this respect, the occlusion technique and its associated measures are claimed to be reliable indicators of potential visual demand. In particular, it has been argued that the technique provides more information than other economical methods based on task time whilst stationary (static task time), such as the `15-second rule´. To investigate these assertions, a study compared results from an occlusion assessment and a road-based assessment. Sixteen drivers carried out two tasks using two user-interfaces under three conditions: statically, full vision, statically, restricted vision (occlusion), and whilst driving. Occlusion was found to be a valid technique. In particular, it may be used to distinguish between tasks based on their level of visual demand. It is concluded that occlusion offers advantages over other methods but requires a robust prototype for results to be meaningful