Adaptation mechanisms in spatial vision--II. Flash thresholds and background adaptation.
To examine how the mechanisms of light adaptation affect spatial pattern vision, contrast detection thresholds were measured for sinusoidal (increment-Gabor) probes on flashed backgrounds in the presence of steady adapting backgrounds. The thresholds for all spatial frequencies (1-12 c/deg), flashed-background intensities (dark to 4 log td) and adapting-background intensities (dark to 4 log td) were adequately described by a simple model consisting of a compressive nonlinearity (a modified Naka-Rushton function), a subtractive adaptation factor, and a multiplicative adaptation factor. For all five subjects the compressive nonlinearity was found to vary systematically with spatial frequency; for all but one subject, the subtractive and multiplicative factors were found to be relatively constant.
Kortum
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PT
Center for Vision and Image Sciences, University of Texas at Austin 78712, USA.
Geisler
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WS
D000221:Adaptation, Ocular / Q000502:physiology*; D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D008960:Models, Psychological; D010364:Pattern Recognition, Visual / Q000502:physiology*; D011601:Psychophysics; D012684:Sensory Thresholds / Q000502:physiology