Effects of different levels of refractive blur on night-time pedestrian visibility

Wood, Joanne M., Marszalek, Ralph P., Carberry, Trent P., Lacherez, Philippe F., & Collins, Michael J. (2015) Effects of different levels of refractive blur on night-time pedestrian visibility. Investigative Ophthalmology and Visual Science, 56(8), pp. 4480-4485.

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The aim of this study was to systematically investigate the effect of different levels of refractive blur and driver age on night-time pedestrian recognition and determine whether clothing that has been shown to improve pedestrian conspicuity is robust to the effects of blur.


Night-time pedestrian recognition was measured for 24 visually normal participants (12 younger M=24.9±4.5 years and 12 older adults M=77.6±5.7 years) for three levels of binocular blur (+0.50 D, +1.00 D, +2.00 D) compared to baseline (optimal refractive correction). Pedestrians walked in place on a closed road circuit and wore one of three clothing conditions: i) everyday clothing, ii) a retro-reflective vest and iii) retro-reflective tape positioned on the extremities in a configuration that conveyed biological motion (known as “biomotion”); the order of conditions was randomized between participants. Pedestrian recognition distances were recorded for each blur and pedestrian clothing combination while participants drove an instrumented vehicle around a closed road course.


The recognition distances for pedestrians were significantly reduced (p<0.05) by all levels of blur compared to baseline. Pedestrians wearing “biomotion” clothing were recognized at significantly longer distances than for the other clothing configurations in all blur conditions. However, these effects were smaller for the older adults, who had much shorter recognition distances for all conditions tested.


In summary, even small amounts of blur had a significant detrimental effect on night-time pedestrian recognition. Biomotion retro-reflective clothing was effective, even under moderately degraded visibility conditions, for both young and older drivers.

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3 citations in Scopus
3 citations in Web of Science®
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ID Code: 84548
Item Type: Journal Article
Refereed: Yes
Additional URLs:
DOI: 10.1167/iovs.14-16096
ISSN: 1552-5783
Divisions: Current > Institutes > Institute of Health and Biomedical Innovation
Copyright Owner: Copyright 2015 Association for Research in Vision and Ophthalmology
Deposited On: 27 May 2015 23:04
Last Modified: 14 Dec 2015 06:01

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