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David Nguyen-Tri, Rémy Allard, Jocelyn Faubert; No impact of luminance noise on chromatic motion perception. Journal of Vision 2010;10(7):820. doi: 10.1167/10.7.820.
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© ARVO (1962-2015); The Authors (2016-present)
The purpose of the present experiments was to investigate the mechanism underlying the perception of chromatic motion. In Experiment 1, we measured contrast thresholds in a direction discrimination task at TFs ranging from 1 to 16 Hz. Results show a bandpass sensitivity function for luminance motion, and lowpass function for chromatic motion, with greater sensitivity for chromatic motion at TFs below 4 Hz, roughly equal sensitivities at 4 Hz, and greater sensitivity to luminance motion at TFs above 4 Hz. In Experiment 2, a direction discrimination task was used to measure contrast thresholds for luminance and chromatic motion as a function of noise contrast in two conditions: an intra-attribute condition (luminance signal and noise, chromatic signal and noise) and an inter-attribute condition (luminance signal with chromatic noise, chromatic signal with luminance noise). Analysis of threshold versus noise contrast curves in the intra-attribute condition shows different calculation efficiencies and levels of internal equivalent noise for luminance and chromatic motion direction discrimination. Inter-attribute noise failed to produce an increase in contrast thresholds at any TF. This shows a double dissociation between colour and luminance motion processing. Taken together, the results of Experiments 1 and 2 indicate that chromatic motion and luminance motion are processed by distinct mechanisms and are consistent with the notion that chromatic motion is processed by a tracking mechanism. Further experiments will investigate the mechanism underlying chromatic motion processing at higher TFs.
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