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Vision Res. Vol. 33, No. I, pp. 47-54, 1993 0042-6989/93 $5.00 + 0.00 Printed in Great Britain. All rights reserved Copyright cc 1993 Pergamon Press Ltd
 

Summary: Vision Res. Vol. 33, No. I, pp. 47-54, 1993 0042-6989/93 $5.00 + 0.00
Printed in Great Britain. All rights reserved Copyright cc 1993 Pergamon Press Ltd
Properties of the Visual Channels that
Underlie Adaptation to Gradual Change of
Luminance
KARIN ARNOLD,* STUART ANSTISt
Received 15 February 1991; in revisedform 5 June 1992
Following adaptation to a spatially uniform patch of light that is gradually brightening (or dimming),
a steady test patch appears to be gradually dimming (or brightening). We measured this ramp
aftereffect with a nulling method, as a function of the amplitude and temporal repetition rate of the
adapting sawtooth waveform and at various retinal eccentricities and levels of dark adaptation. We
conclude that the underlying visual channels respond best to large-amplitude sweeps in luminance of
at least 20 dB (1 log unit); but they are fairly insensitive to the temporal rate of this sweep. The
channels are present out to an eccentricity of at least 40 but they almost disappear during dark
adaptation. The ramp aftereffects were asymmetrical: the subjectively darkening aftereffect produced
by a brightening adapting ramp was slightly stronger than vice versa.
Psychophysics Ramp aftereffect Eccentricity Dark adaptation Luminance increment Asymmetry
INTRODUCTION
It is a truism that the visual system is designed to
respond better to changing stimuli than to steady states.

  

Source: Anstis, Stuart - Department of Psychology, University of California at San Diego

 

Collections: Biology and Medicine