Suppressive effect of sustained low-contrast adaptation followed by transient high-contrast on peripheral target detection.
We observed that presenting a low-contrast Gabor patch (2 cpd, 5 degrees eccentricity, contrast=4%) for 8 s and then flashing a 20-30 ms 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<0.00001). 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.
Moradi
Farshad
F
Computation and Neural Systems Program, California Institute of Technology, Pasadena, CA 91125, USA. farshadm@caltech.edu
Shimojo
Shinsuke
S
D000221:Adaptation, Ocular / Q000502:physiology*; D015350:Contrast Sensitivity / Q000502:physiology*; D006801:Humans; D010470:Perceptual Masking / Q000502:physiology; D011601:Psychophysics