VISIBILITY LOSSES CAUSED BY TRANSIENT ADAPTATION AT LOW LUMINANCE LEVELS

Transient adaptation refers to the rapid fluctuations in the sensitivity of the eye that result from sudden changes in luminance level. The research reported here examines the effects of transient adaptation and resultant losses in visibility by using luminance levels comparable to nighttime highway lighting conditions. At low luminance levels, sudden increases produce losses in visibility equivalent to those previously founded at higher levels. However, at low luminance levels, decreases produce smaller losses than those observed at higher luminance levels. The results also suggest that there is a preadapting level or range of levels below which there is little or no difference between visibility losses for 10- and 100-fold decreases and above which there is a difference. The transition appears to be a gradual one and is complete at about 8 ft L. The findings of these investigations suggest that visibility loss depends more on the ratio of steady-state thresholds, particularly at low luminance levels, than on the ratio of luminance change as previously supposed. Research has been initiated on the problem of nonuniformities in roadway luminances in the motorist's visual environment. Results indicate that the size of a nonuniformity may have little effect on transient adaptation. However, experiments to examine multiple nonuniformities and the effect of nonuniformities at various distances from the line of sight on transient adaptation are planned.

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    • Presented at a symposium conducted by TRB, September 4-6, 1974 at Ohio State University, and sponsored by TRB, Illuminating Engineering Research Institute, Ohio University and Ohio Department of Transportation. Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved
  • Corporate Authors:

    Transportation Research Board (TRB)

    Washington, DC   
  • Authors:
    • Rinalducci, Edward J
    • Beare, Arthur N
  • Conference:
  • Publication Date: 1975

Media Info

  • Media Type: Print
  • Features: Figures; References;
  • Pagination: pp 11-22
  • Monograph Title: Driver visual needs in night driving: proceedings of a symposium conducted by the Transportation Research Board, September 4-6, 1974
  • Serial:

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Filing Info

  • Accession Number: 00129390
  • Record Type: Publication
  • Report/Paper Numbers: HS-017 803
  • Files: TRIS, TRB, ATRI
  • Created Date: Apr 21 1976 12:00AM