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Second-order spatial frequency and orientation channels in human vision.

Dave Ellemberg·Harriet A Allen·Robert F Hess
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Abstract

We compared the number of spatial frequency and orientation mechanisms underlying first- versus second-order processing by measuring discrimination at detection threshold for first- and second-order Gabors to determine the smallest difference in spatial frequency and orientation that permits accurate discrimination at threshold. For second-order gratings, the number of channels is the same as for first-order gratings for spatial frequencies up to about 2 cpd; however, there are fewer second-order channels at higher spatial frequencies. In contrast, the number of labeled channels for orientation is the same for first- and second-order gratings. In conclusion, our findings provide evidence for distinct spatial frequency and orientation labeled detectors in second-order visual processing. We also show that, relative to first-order, there are fewer second-order channels processing higher spatial frequencies. This is consistent with a filter-rectify-filter scheme for second-order in which the second stage of filtering is at lower spatial frequencies.

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Contrast SensitivityDiscrimination, PsychologicalHumansOrientationPattern Recognition, VisualPhotic StimulationPsychometricsPsychophysicsSensory ThresholdsJournal ArticleResearch Support, Non-U.S. Gov't

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Dave Ellemberg, Harriet A Allen, Robert F Hess. 2006-03-20. Second-order spatial frequency and orientation channels in human vision.. https://doi.org/10.1016/j.visres.2006.01.028

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