DARK ADAPTATION IN THE PRESENCE OF WANING BACKGROUND LUMINANCES

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

• Supplemental Notes:
  • Vol 62, No 2, PP 177-181
• Corporate Authors:

  American Institute of Physics

  One Physics Ellipse
  College Park, MD  United States  20740-3843
• Authors:
  • Spillmann, L
  • Nowlan, A T
  • Bernholz, C D
• Publication Date: 1972-2

Media Info

• Serial:
  • Optical Society America Journal

Subject/Index Terms

• TRT Terms: Brightness; Light; Night; Night vision; Perception; Psychological adaptation; Transients
• Old TRIS Terms: Thresholds (Perception)
• Subject Areas: Highways; Safety and Human Factors;

Filing Info

• Accession Number: 00221570
• Record Type: Publication
• Files: TRIS
• Created Date: May 9 1972 12:00AM