Authors: Richard T Dyde A David Milner
Publish Date: 2002/04/13
Volume: 144, Issue: 4, Pages: 518-527
Abstract
In a series of three separate experiments we studied two different orientation illusions in both of which vertical lines appear tilted as a result of being set against a tilted background pattern The ‘simultaneous tilt illusion’ STI in which a target grating is viewed within an abutting tilted grating surround is thought to originate early in the cortical processing of visual contours In contrast the ‘rodandframe’ illusion RFI which is induced by a distant tilted frame is thought to originate much later in the perceptual processing system In the first two experiments we found that orientationguided action was virtually impervious to the RFI whereas both perceptual experience and action were equally influenced by the STI In the third experiment in which the two illusions were pitted one against the other an opposite pattern of effects emerged such that visuomotor performance was now deceived by the illusion much more than was perceptual experience This pattern of association and dissociation in the effects of visual illusions on perception versus action can best be explained within a twovisualsystems model of cortical processing
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