Responses to visual, tactile and visual–tactile forward collision warnings while gaze on and off the road

• Three types of forward collision warnings were investigated in a driving simulator.
• Visual warnings were responded slower than tactile and visual–tactile warnings.
• Driver’s visual orientation affected brake reaction times to visual warnings.
• Tactile and visual–tactile warnings remained unaffected by visual orientation.

The objective of the current driving simulator study (N = 20) was to assess brake reaction time (BRT) and subjective experiences of visual (V), tactile (T), and visual–tactile (VT) collision warnings when the drivers’ visual orientation was manipulated between four locations (i.e., road and three different mirror locations). V warning was a blinking light in a windscreen, T warning was implemented by a vibrating accelerator pedal, and VT warning was their synchronous combination. The results showed that all the warning stimuli were detected in 100% accuracy in all visual orientations, but T and VT warnings produced significantly faster BRTs when compared to V warning. It was found that BRT to V warning was the slowest while observing the furthermost side mirror. However, BRTs following T and VT warnings remained unaffected by the visual orientations. Both the objective BRT measurements and subjective evaluations indicated a superiority of T and VT warnings against a sole V warning, not only in general terms, but also separately for different visual orientations.