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T. Takeuchi, K. K. De Valois, J. L. Hardy; The influence of color flicker on the detection of luminance patterns. Journal of Vision 2001;1(3):361. doi: https://doi.org/10.1167/1.3.361.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To examine masking by successive color contrast on the detection of temporally-varying luminance patterns. Methods: Detection threshold contrast of a horizontal luminance-varying sinusoidal grating was estimated by temporal 2AFC combined with a staircase method. Grating spatial frequency was 0.5 cycles/degree. Both flickering and drifting gratings were used. The temporal frequency of grating flicker or drift varied from 0 Hz to 14 Hz. As the grating flickered or drifted, its color alternated between two hues. Each frame of the moving pattern was isochromatic (not isoluminant), but the overall chromaticity of the pattern changed over time. The temporal frequency of color alternation varied from 1 to 24 Hz either as a square-wave or sinusoidally. We chose two hues from a color space based on chromatic tuning characteristics of neurons in the lateral geniculate nucleus (LGN). When flicker was sinusoidal, several intermediate hues were also presented. Sensation luminances for each color pair were equated for each subject by heterochromatic flicker photometry. Results: At high temporal test frequencies, the color alternation produced substantial pattern masking. The amount of masking varied as a single-peaked function centered at a color alternation rate of about 6 Hz, independent of the temporal frequency of the flickering or drifting luminance-varying grating. The masking magnitude was related to the difference in total cone excitation between the two hue extremes. Conclusion: Color plays a critical role in the detection of luminance motion and flicker. The lack of temporal frequency selectivity and the dependence on cone contrast suggest that the hue-selective parvocellular mechanisms influence early processing stages in the magnocellular system.
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