Separate colour-opponent mechanisms underlie the detection and discrimination of moving chromatic targets

Alexandra Willis, Stephen J. Anderson

Research output: Contribution to journalArticle

Abstract

Current opinion holds that human colour vision is mediated primarily via a colour-opponent pathway that carries information about both wavelength and luminance contrast (type I). However, some authors argue that chromatic sensitivity may be limited by a different geniculostriate pathway, which carries information about wavelength alone (type II). We provide psychophysical evidence that both pathways may contribute to the perception of moving, chromatic targets in humans, depending on the nature of the visual discrimination. In experiment 1, we show that adaptation to drifting, red-green stimuli causes reductions in contrast sensitivity for both the detection and direction discrimination of moving chromatic targets. Importantly, the effects of adaptation are not directionally specific. In experiment 2, we show that adaptation to luminance gratings results in reduced sensitivity for the direction discrimination, but not the detection of moving chromatic targets. We suggest that sensitivity for the direction discrimination of chromatic targets is limited by a colour-opponent pathway that also conveys luminance-contrast information, whereas the detection of such targets is limited by a pathway with access to colour information alone. The properties of these pathways are consistent with the known properties of type-I and type-II neurons of the primate parvocellular lateral geniculate nucleus and their cortical projections. These findings may explain the known differences between detection and direction discrimination thresholds for chromatic targets moving at low to moderate velocities.
Original languageEnglish
Pages (from-to)2435-41
Number of pages7
JournalProceeding of the Royal Society: Series B
Volume265
Issue number1413
DOIs
Publication statusPublished - 22 Dec 1998

Fingerprint

Color
Luminance
color
Color vision
wavelength
Wavelength
primate
Neurons
wavelengths
experiment
Experiments
Geniculate Bodies
Direction compound
Discrimination (Psychology)
detection
Color Vision
color vision
Access to Information
Contrast Sensitivity
Primates

Keywords

  • colour
  • contrast sensitivity
  • human vision
  • isoluminant
  • motion
  • perception

Cite this

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abstract = "Current opinion holds that human colour vision is mediated primarily via a colour-opponent pathway that carries information about both wavelength and luminance contrast (type I). However, some authors argue that chromatic sensitivity may be limited by a different geniculostriate pathway, which carries information about wavelength alone (type II). We provide psychophysical evidence that both pathways may contribute to the perception of moving, chromatic targets in humans, depending on the nature of the visual discrimination. In experiment 1, we show that adaptation to drifting, red-green stimuli causes reductions in contrast sensitivity for both the detection and direction discrimination of moving chromatic targets. Importantly, the effects of adaptation are not directionally specific. In experiment 2, we show that adaptation to luminance gratings results in reduced sensitivity for the direction discrimination, but not the detection of moving chromatic targets. We suggest that sensitivity for the direction discrimination of chromatic targets is limited by a colour-opponent pathway that also conveys luminance-contrast information, whereas the detection of such targets is limited by a pathway with access to colour information alone. The properties of these pathways are consistent with the known properties of type-I and type-II neurons of the primate parvocellular lateral geniculate nucleus and their cortical projections. These findings may explain the known differences between detection and direction discrimination thresholds for chromatic targets moving at low to moderate velocities.",
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Separate colour-opponent mechanisms underlie the detection and discrimination of moving chromatic targets. / Willis, Alexandra; Anderson, Stephen J.

In: Proceeding of the Royal Society: Series B, Vol. 265, No. 1413, 22.12.1998, p. 2435-41.

Research output: Contribution to journalArticle

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