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Suppressive Effect of Sustained Low-Contrast Adaptation followed by Transient High-Contrast on Peripheral Target Detection

Farshad Moradi, Shinsuke Shimojo


We observed that presenting a low-contrast Gabor patch (2cpd, 5deg eccentricity, contrast = 4%) for 8 seconds and then flashing a 20-30ms high-contrast patch over it could elicit the perceptual disappearance of a subsequent low-contrast stimulus, whereas neither low-contrast adaptation nor high-contrast flash alone had any considerable effect (p<.00001). In other experiments we found: a) suppressive components are phase-insensitive, b) the effect transfers between eyes, c) suppression is selective for orientation, and d) the induction by the transient high-contrast Gabor patch could be transferred to another previously adapted location up to a few degrees. Results indicate synergy between contrast and adaptation through a non-linear interaction between rapid gain adjustment to transient change and adaptation to sustained spatial patterns. Findings are compatible with non-local mechanisms presumably at the cortical level.

Preprint of the paper