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Jianliang Tong, Zhi-Lei Zhang, Christopher Cantor, Clifton Schor; The effect of perceptual grouping on perisaccadic spatial distortion. Journal of Vision 2010;10(7):512. doi: https://doi.org/10.1167/10.7.512.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Target flashes immediately before the onset of a saccade appear displaced in the direction of the saccade (perisaccadic spatial distortion). In this study we observed that the horizontal spatial distortions of flashes presented above the fovea, immediately before a horizontal saccade, increase with retinal eccentricity. We also investigated perceptual interactions between spatial distortions produced with two brief (1 ms) flashes presented simultaneously at different retinal elevations from the fovea. Methods: In condition one, single or horizontally-aligned paired (synchronous) flashes were presented at combinations of three different elevations (1, 4 and 8 deg) above the fixation target before the onset of a horizontal saccade. In condition two, paired flashes were presented with misalignment in both horizontal (4 deg) and vertical (1 deg) directions. Observers reported the perceived horizontal location of each flash in both conditions. Results: The amount of perceptual mislocalization increased with vertical eccentricity with single-flashed targets. In condition one, vertically-aligned pairs of simultaneous flashes presented at different elevations were distorted equally by an amount approximately equal to the average of single flash distortions, and distortions of paired flashes had the same horizontal offset as presented in the retinal image in condition two. Paired perisaccadic distortions were the same for monoptic and dichoptic conditions. Conclusions: Our results suggested that perisaccadic spatial distortions resulting from flashes at different eccentricities undergo perceptual grouping associated with their simultaneous presentation. Grouping most likely occurs after the stage of binocular integration of distorted visual directions.
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