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Joanne M Wood, Richard Tyrrell, Alex A Black, Philippe F Lacherez; Exploring the role of biological motion in enhancing night-time pedestrian recognition: assessment of eye movements. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):4305. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To examine drivers’ eye movements as they approach pedestrians wearing retroreflective markers in a configuration that conveys biological motion (known as “biomotion”).
Twenty visually normal participants (M=24.35 ± 6.42 years) drove an instrumented vehicle (incorporating a custom-built distance measurement system) around a 1.8 km closed-road circuit at night. Pedestrians wore black clothing and walked in place at two different locations along the course, and faced either towards or away from the roadway. Pedestrians wore two conspicuity treatments - either a standard retroreflective vest or a retroreflective vest with additional retroreflective tape positioned on the extremities in a configuration that conveyed biological motion (biomotion). Participants pressed a response pad when they first recognized that a pedestrian was present and again when they first detected the direction that the pedestrian was walking. Eye movements were recorded (ASL Mobile Eye) to characterize drivers’ fixation behaviours when viewing the pedestrians; the time to first gaze at the pedestrian and response time to first recognize the pedestrian were expressed as time relative to the moment when the pedestrian was first in the drivers’ field of view.
Eye movement patterns revealed that the biomotion configuration attracted drivers’ attention significantly sooner compared to the vest (time to first gaze: 1.1 vs 3.5 s). Drivers spent significantly less time fixating on the pedestrian wearing biomotion prior to recognition compared to the vest (3.4 s vs. 6.1 s). As a result the drivers’ response time to first recognize the pedestrian was approximately half that for biomotion compared to the vest (6.4 vs 13.9 s). Consistent with these findings, drivers recognized pedestrians at significantly longer distances when wearing biomotion compared to the vest (331.6 m vs. 185.2 m) and identified the direction of walking at longer distances (220.2 m vs. 87.7 m).
At night the biomotion configuration facilitated earlier recognition of pedestrians and identification of their walking direction, thus enhancing drivers’ capacity to avoid pedestrians. Patterns of eye movements reveal the impact of pedestrian conspicuity on drivers’ attention and gaze behaviors at night-time.
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