The effect of communicational signals on drivers' subjective appraisal and visual attention during interactive driving scenarios

Communicational signals (e.g. lights and horns) are imperative for on-road interaction between drivers. The aim of the present study was to explore how these signals affect drivers' subjective appraisal and visual attention, and how drivers decode the signals from other vehicles within a variety of interactive contexts. Twenty-five male participants (20 valid samples, ranging from 21 to 29 years of age) were recruited to watch film clips of pre-designed interactive scenarios involving common vehicle signals in a full-view simulator (i.e. including road view and mirror views). Participants' attitudes towards the interacting vehicle's behaviours, emotional responses, fixation metrics, and decoded meanings were recorded and analysed. The majority of tested signals, with the exception of the horn used in the behind vehicles, significantly improved drivers' attitudes and pleasure. All signals significantly increased emotional arousal, as well as the total fixation time and mean fixation duration on the interacting vehicle. When the interacting vehicle was visible in mirrors, the signal usage significantly increased the fixation frequency towards it. Meanwhile, a significant decrease in total fixation time and mean fixation duration on the road was reported. The results also demonstrated that the decoded signal contained several meanings simultaneously depending on both the signal type and its interactive context. This study quantified the communication process via vehicular signals under typical situations involving other vehicles, and also suggested new ideas on how to establish more advanced communication between drivers.