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Johnell O. Brooks, Talissa A. Frank, Robert W. Isenhower, Nathan D. Klein, Jordan Addison, Richard A. Tyrrell; Steering performance in challenging visual conditions: Testing the selective degradation hypothesis. Journal of Vision 2004;4(8):812. doi: https://doi.org/10.1167/4.8.812.
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© ARVO (1962-2015); The Authors (2016-present)
The selective degradation hypothesis predicts that drivers are overconfident of their ability to drive safely at night because their ability to steer is preserved while their ability to recognize details is impaired. Two experiments extend previous research (Leibowitz & Owens, 1977; Owens & Tyrrell, 1999; Owens, 2003) by asking young licensed drivers to drive a high fidelity fixed-based driving simulator (150° horizontal forward view). Participants drove along a curvy rural road and were instructed to stay in their lane, to maintain their speed at approximately 55 mph, and to indicate the presence of pedestrians. In Experiment 1, ten participants spent five minutes driving with five levels of blur (0, +1, +2, +5, and +10 diopters), four levels of luminance (16.7, 1.0, 0.03 and 0.003 cd/m2), and two visual field sizes (full binocular and 1.7 degree monocular fields). Even when driving with extreme blur and with extremely low luminance, drivers stayed inside their lane at least 80% of the time. But steering performance was severely degraded when visual field size was reduced. Although visual acuity was significantly degraded by both blur and low luminance but not by visual field reduction, drivers' ability to identify the presence of pedestrians was significantly impaired when visual field was reduced. Experiment 2 explored the relationship between steering ability and visual field size by asking ten new participants to drive with each of seven visual field sizes (full binocular field, full monocular field, and monocular fields of 45.9, 22.8, 10.8, 3.4, and 1.7 degrees). Steering performance was robust with relatively large field sizes; drivers were in their lane 98% of the time with a monocular field of 45.9 degrees. With smaller field sizes, however, steering performance declined dramatically (p < .001). Drivers with a monocular field size of 1.7 degrees were in their lane only 29% of the time. These findings support and extend the selective degradation hypothesis.
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