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Alex A Black, Chiau-Ni Chiu, Gie Kim, Jenny Le, Hyun Lee, Tien Nguyen, Joanne M Wood; Effect of refractive blur on judgment of pedestrian walking direction at night-time. Invest. Ophthalmol. Vis. Sci. 2018;59(9):1289. doi: https://doi.org/.
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Poor conspicuity is believed to be a leading cause of fatal pedestrian crashes at night. Retro-reflective clothing has been used to enhance night-time conspicuity, particularly when placed on the moveable joints in a biomotion configuration. This study explored the effects of refractive blur on the accuracy and confidence level in judging the walking direction of pedestrians wearing biomotion retro-reflective clothing at night-time.
Participants included 20 visually normal young adults (M=21.8±1.6 years). Testing was conducted at night-time on a closed road circuit. Participants were seated in a stationary vehicle with low beam headlamps, and judged the direction of walking of a pedestrian located 135m ahead, under three levels of binocular spherical blur (best-correction (no blur), +0.50D and +1.00D). The pedestrian wore one of three retro-reflective clothing configurations (vest, thick or thin strips of retro-reflective materials in a biomotion configuration) and walked in one of three directions (straight across, away or towards the car). Participants indicated the direction of pedestrian motion and self-rated their confidence for each response (0% least confident to 100% most confident).
Increasing levels of refractive blur significantly reduced the accuracy in judging the direction of pedestrian motion (p<0.001; 73% correct for no blur, 64% for +0.50D blur and 53% for +1.00D blur). The vest configuration had lowest accuracy compared to the two biomotion configurations (p<0.001; 53% correct for vest, with similar levels for thick and thin biomotion strips, 69% vs 68% respectively). Similar findings were found for self-reported response confidence, with reduced confidence with greater refractive blur (p<0.001) and for the vest configuration (p=0.002). Importantly, self-reported confidence correlated poorly with accuracy (p=0.83).
The ability to recognize pedestrian walking direction at night was significantly impaired by refractive blur, and clothing incorporating retro-reflective strips in a biomotion configuration can significantly improve pedestrian conspicuity. The findings highlight the importance of using optimal correction for driving, especially at night, to maximize a driver’s ability to recognise other vulnerable road users.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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