Daniel Eisele & Tibor Petzoldt

Highlights #

A video-based online study was conducted.
The presence of a frontal brake light (FBL) on a vehicle was manipulated.
An active FBL on yielding vehicles led to increased willingness to cross the street.
An inactive FBL on non-yielding vehicles led to decreased willingness to cross.
Future research should consider possible effects of inactive eHMIs.

Abstract #

Effects of a frontal brake light (FBL, a potential external human–machine interface for automated vehicles) on participants’ self-reported willingness to cross a vehicle’s path were investigated. In a mixed design online study (vehicles in the experimental group were equipped with FBLs, there were no FBLs in the control group), par- ticipants observed videos of a vehicle approaching at different speeds from the perspective of a pedestrian standing at the curb. The vehicles exhibited either yielding behavior (braking onset 55 m or 32 m before standstill in front of the pedestrian’s position) or non-yielding behavior (approach speed was maintained). Participants specified their willingness to cross the vehicle’s path at different distances. When the vehicle yielded (i.e., FBL was activated), willingness to cross was significantly higher in the experimental group than the control group. Notably, we further observed a significantly lower willingness to cross in the experimental group than the control group when the vehicle did not yield (i.e., FBL was deactivated). Novel external human–machine in- terfaces might therefore influence the interaction with vehicles not only when they are activated but also when they are deactivated.