The effect of alarm timing on driver behaviour: an investigation of differences in driver trust and response to alarms according to alarm timing

The present paper describes a study concerned with the effect of alarm timing on driver trust and behaviour with a Forward Collision Warning System (FCWS). In this driving simulator experiment three different kinds of alarm timing (late/middle/early) were compared with respect to driver braking strategy and driver trust. The results showed that early alarm timing led to a more timely response to an imminent collision than either middle or late timing. With respect to driver trust, trust in late alarm timing is low compared with early or middle alarm timing. Furthermore the relationship between the timing of accelerator release and the timing of alarm onset is an important cause of changes in trust and if alarms are presented after drivers have already started to brake then trust is impaired. Middle alarm timing has the potential to improve driver braking response to imminent collisions. Possible benefits and drawbacks of FCWS are discussed from the viewpoint of alarm timing.