How should external human-machine interfaces behave? Examining the effects of colour, position, message, activation distance, vehicle yielding, and visual distraction among 1,434 participants

Bazilinskyy, P.; Kooijman, L.; Dodou, D.; de Winter, J.C.F.

doi:10.1016/j.apergo.2021.103450

How should external human-machine interfaces behave? Examining the effects of colour, position, message, activation distance, vehicle yielding, and visual distraction among 1,434 participants

Title

How should external human-machine interfaces behave? Examining the effects of colour, position, message, activation distance, vehicle yielding, and visual distraction among 1,434 participants

Author

Bazilinskyy, P. (TU Delft Human-Robot Interaction)
Kooijman, L. (TU Delft Medical Instruments & Bio-Inspired Technology)
Dodou, D. (TU Delft Medical Instruments & Bio-Inspired Technology)
de Winter, J.C.F. (TU Delft Human-Robot Interaction)

Date

2021

Abstract

External human-machine interfaces (eHMIs) may be useful for communicating the intention of an automated vehicle (AV) to a pedestrian, but it is unclear which eHMI design is most effective. In a crowdsourced experiment, we examined the effects of (1) colour (red, green, cyan), (2) position (roof, bumper, windshield), (3) message (WALK, DON'T WALK, WILL STOP, WON'T STOP, light bar), (4) activation distance (35 or 50 m from the pedestrian), and (5) the presence of visual distraction in the environment, on pedestrians' perceived safety of crossing the road in front of yielding and non-yielding AVs. Participants (N = 1434) had to press a key when they felt safe to cross while watching a random 40 out of 276 videos of an approaching AV with eHMI. Results showed that (1) green and cyan eHMIs led to higher perceived safety of crossing than red eHMIs; no significant difference was found between green and cyan, (2) eHMIs on the bumper and roof were more effective than eHMIs on the windshield, (3) for yielding AVs, perceived safety was higher for WALK compared to WILL STOP, followed by the light bar; for non-yielding AVs, a red bar yielded similar results to red text, (4) for yielding AVs, a red bar caused lower perceived safety when activated early compared to late, whereas green/cyan WALK led to higher perceived safety when activated late compared to early, and (5) distraction had no significant effect. We conclude that people adopt an egocentric perspective, that the windshield is an ineffective position, that the often-recommended colour cyan may have to be avoided, and that eHMI activation distance has intricate effects related to onset saliency.

Subject

Automated driving
Crowdsourcing
Distraction
eHMI
Pedestrian safety

To reference this document use:

http://resolver.tudelft.nl/uuid:97a46ffe-2dab-43c0-ba77-5fdac765a753

DOI

https://doi.org/10.1016/j.apergo.2021.103450

ISSN

0003-6870

Source

Applied Ergonomics: human factors in technology and society, 95

Part of collection

Institutional Repository