title: Motion extrapolation in the central fovea.
abstract: Neural transmission latency would introduce a spatial lag when an object moves across the visual field, if the latency was not compensated. A visual predictive mechanism has been proposed, which overcomes such spatial lag by extrapolating the position of the moving object forward. However, a forward position shift is often absent if the object abruptly stops moving (motion-termination). A recent "correction-for-extrapolation" hypothesis suggests that the absence of forward shifts is caused by sensory signals representing 'failed' predictions. Thus far, this hypothesis has been tested only for extra-foveal retinal locations. We tested this hypothesis using two foveal scotomas: scotoma to dim light and scotoma to blue light. We found that the perceived position of a dim dot is extrapolated into the fovea during motion-termination. Next, we compared the perceived position shifts of a blue versus a green moving dot. As predicted the extrapolation at motion-termination was only found with the blue moving dot. The results provide new evidence for the correction-for-extrapolation hypothesis for the region with highest spatial acuity, the fovea.
authors.affiliation: Department Psychologie, Ludwig-Maximilians-Universität München, Munich, Germany. shi@psy.lmu.de
authors.forename: Zhuanghua
authors.initials: Z
authors.lastname: Shi
authors.forename: Romi
authors.initials: R
authors.lastname: Nijhawan
mesh_terms: D003116:Color; D005260:Female; D005403:Fixation, Ocular / Q000502:physiology; D005584:Fovea Centralis / Q000502:physiology*; D006801:Humans; D008297:Male; D008954:Models, Biological; D008959:Models, Neurological; D009039:Motion Perception / Q000502:physiology*; D009898:Optic Disk / Q000502:physiology; D010775:Photic Stimulation; D014785:Vision, Ocular / Q000502:physiology*