Spatio-temporal distortions of visual perception during saccades
Single Paper Presentation

Paola Binda
Department of Psychology, Università Vita-Salute San Raffaele, Via Olgettina 58, Milan, Italy; Italian Institute of Technology (IIT), Via Morego 30, G

David Burr
Department of Psychology, Università Degli Studi di Firenze, Via S. Niccolo` 89 Florence, Italy; Department of Psychology, University of Western Australia, Stirling Hw., Nedlands Perth, Western Australia, Australia

Concetta Morrone
Department of Psychology, Università Vita-Salute San Raffaele, Via Olgettina 58, Milan, Italy; Istituto Nazionale di Neuroscienze, Italy

     Abstract ID Number: 93
     Full text: Not available
     Last modified: May 30, 2007
     Presentation date: 07/06/2007 8:40 AM in Quad General Lecture Theatre
     (View Schedule)

Abstract
Both space and time are grossly distorted during saccadic eye-movements (Ross et al., Nature 1997; Morrone et al., Nat. Neurosci. 2005). In this study we measured simultaneously spatial and temporal localization of visual stimuli during saccades (previously measured separately). On each trial, subjects responded to two questions: where did the bar appear in space (relative to a remembered ruler)? and was it closer in time to the first or second auditory tone? The two tones were separated from each other by 200 ms, straddling the visual presentation with a variable delay, allowing us to compute a psychometric function, and estimate the perceived time of bar presentation. During fixation, and well before or after a saccade, the bar was localized veridically in space and in time with high precision. Perisaccadically, bars were spatially mislocalized toward the saccadic target (as previously observed), and temporally mislocalized some 80 ms later than their actual presentation. The magnitude of the perceived delay varied with spatial position, being greater for stimuli veridically or illusory localized near the saccadic target. These results reinforce previous evidence for the spatial selectivity of event-timing mechanisms (Johnston et al., Curr. Biol. 2006), and suggest strong similarities between perisaccadic spatial and temporal distortions.