Location

Stevenson, Washington

Date

10-7-2007

Session

Session 2 – Lectures Visual Performance & Attention

Abstract

Because of the low light levels that are important in night driving, it is possible that both rods and cones contribute to visual performance for drivers at night. However, little evidence has been available about the relative contributions of these classes of photoreceptors. Partly, this may be because until recently the range of light sources has been limited, and consequently the question was not of great practical importance, at least for photometry. However, there is now a much larger variety of sources in use for vehicle lighting, including high-intensity discharge (HID) and light emitting diode (LED) sources. The greater variety of sources and spectral power distributions has increased interest in how the visual response of a driver’s eyes at night varies with wavelength. New evidence indicates that the relative contributions of rods and cones may be different for different driving tasks or different aspects of a driver’s visual experience at night: detection of pedestrians—the task that is most critically affected by darkness— may depend primarily on cones, while subjective impressions of brightness, and perhaps the conspicuity of emergency signals in the visual periphery, may be strongly influenced by rods.

Rights

Copyright © 2007 the author(s)

DC Citation

Proceedings of the Fourth International Driving Symposium on Human Factors in Driver Assessment, Training and Vehicle Design, July 9-12, 2007, Stevenson, Washington. Iowa City, IA: Public Policy Center, University of Iowa, 2007: 25-31.

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Jul 10th, 12:00 AM

Vision in Night Driving: The Roles of Rod and Cone Photoreceptors

Stevenson, Washington

Because of the low light levels that are important in night driving, it is possible that both rods and cones contribute to visual performance for drivers at night. However, little evidence has been available about the relative contributions of these classes of photoreceptors. Partly, this may be because until recently the range of light sources has been limited, and consequently the question was not of great practical importance, at least for photometry. However, there is now a much larger variety of sources in use for vehicle lighting, including high-intensity discharge (HID) and light emitting diode (LED) sources. The greater variety of sources and spectral power distributions has increased interest in how the visual response of a driver’s eyes at night varies with wavelength. New evidence indicates that the relative contributions of rods and cones may be different for different driving tasks or different aspects of a driver’s visual experience at night: detection of pedestrians—the task that is most critically affected by darkness— may depend primarily on cones, while subjective impressions of brightness, and perhaps the conspicuity of emergency signals in the visual periphery, may be strongly influenced by rods.