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Patrick Monnier, Joshua Edler, Ryann McGough; Estimating the properties of the chromatic mechanisms mediating the processing of large color differences. Journal of Vision 2010;10(15):6. doi: 10.1167/10.15.6.
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© ARVO (1962-2015); The Authors (2016-present)
BACKGROUND: Many properties of the mechanisms mediating supra-threshold color vision still elude us. Here, we used a visual search task in conjunction with a two-sided noise-masking approach (Hansen & Gegenfurtner, 2006) to test the feasibility of the paradigm to study the processing of large color differences.
METHODS: A 2AFC visual search task was performed with variegated elements in which a target, when present, differed from distractors in the variance of the chromatic variegation (target and distractors were identical in space-average chromaticity). Vectors in color space were used to express signal and noise chromaticities. Distractors were assigned noise chromaticities and the target consisted of signal chromaticities added to the noise. Signal vector length was adjusted in staircases to estimate threshold. The relative angle between signal and noise vectors was varied systematically to estimate the bandwidth of the mechanisms mediating the task. Search performance was tested for signals along cardinal as well as intermediate diagonal directions in color space to test the number and properties of the chromatic mechanisms mediating the task. Last, the number of search elements presented simultaneously was varied to establish the attentional demands of the task.
RESULTS: Thresholds were generally elevated when the noise vectors were near the signal vector and decreased with noise vector angle. The shape of these functions was generally shallow and similar across signal directions and set size.
CONCLUSION: The visual search task in conjunction with a noise-masking approach is a viable paradigm to study the processing of large color differences.
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