Egocentric but not allocentric perceptual distortions from saccadic adaptation

摘要

Saccadic adaptation, the ability to progressively shift the endpoint of a saccade to take into account changes in the location of a visual target [McLaughlin, 1967] also results in visual compression of the adapted region [Bahcall & Kowler, 1999]. More recently, it has been proposed that saccadic adaptation induces a perceptual mislocalization even during fixation, and that this is caused by a distortion of visual space at the adapted location [Zimmermann and Lappe, 2010]. Prompted by this work, we induced saccadic adaptation and measured subjects' pointing movements to the perceived post-saccade target location; we found that subjects could adapt, both inwardly and outwardly and that their motor response data exhibited the expected distortion. We followed this with interleaved top-up saccadic adaptation trials and vernier alignment trials, in which subjects judged the position of a flashed target relative to distant static flankers. There was no consistent change in the perceived alignment of the vernier target relative to the flankers following saccadic adaptation. The mislocalizations from saccadic adaptation therefore do not seem to be in an allocentric representation of space but are more likely confined to motor/egocentric space.