Abstract
Aim: Regularity is a fundamental characteristic of the visual environment. Here we consider whether regularity is an adaptable feature, specifically whether one can obtain an after-effect (AE) in perceived regularity. Method: Stimuli consisted of a 7 by 7 arrangement of dark Gaussian blobs arranged on a baseline grid. The position of each blob was randomly jittered from its baseline position by an amount that determined the degree of pattern irregularity. Observers adapted for 60 sec to a pair of patterns above and below fixation with a different amount of regularity, then adjusted the relative regularity of two test patterns to obtain the PSE. The size of the AE was given by the difference in regularity at the PSE. Results: PSEs were significantly different from zero, indicating that regularity is an adaptable feature. Additional experiments indicated that the regularity AE was not due to a) luminance spatial frequency adaptation, b) local positional adaptation or c) local orientation adaptation. Experiments using single adaptors revealed that the AE is unidirectional, specifically that adaptation only causes test patterns to appear less regular. Conclusion: Pattern regularity is an adaptable feature in vision, but the functional significance of regularity adaptation is not yet clear.
This research was supported by a Natural Sciences and Engineering Research Council of Canada (NSERC) grant # OGP01217130 given to F.K.