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Anna Kosovicheva, Oishi Hawlader, Peter Bex; Localization errors following saccadic adaptation to a dichoptic step. Journal of Vision 2018;18(10):1293. doi: 10.1167/18.10.1293.
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In saccadic adaptation, saccade amplitudes change to account for errors in saccade landing location. Saccadic adaptation also produces mislocalizations around the adapted target location (Bahcall & Kowler, 1999; Awater, Burr, Lappe, Morrone, Goldberg, 2005). While saccadic adaptation is typically tested with identical target steps in each eye, previous work has demonstrated that the oculomotor system can adaptively recalibrate saccade amplitudes in response to opposite target shifts in each eye (Maiello, Harrison, & Bex, 2016). We investigate the perceptual effects of adaptation to a dichoptic step: are localization errors consistent with changes in saccade amplitude in different directions in the two eyes? Subjects made repeated rightward saccades to a Gabor target at 8° eccentricity, and shutter glasses were used to introduce a dichoptic step. On saccade onset, the saccade target stepped 0.8° inward in the left eye and 0.8° outward in the right eye, remaining onscreen following saccade completion. After 75 adaptation trials, subjects were shown probe trials (interleaved with top-up adaptation trials) to measure perceptual shifts following adaptation. During probe trials, subjects performed a post-saccadic Vernier discrimination task with a pair of brief (100 ms) lines, each shown to a different eye. Following adaptation, in order to appear collinear, each Vernier line needed to be shifted in the same direction as the adapting step in the corresponding eye. The perceived misalignment was significantly larger compared to a control condition in which subjects adapted to identical inward steps in both eyes (mean total misalignment of -0.44° vs. -0.03°; p = 0.008). Similar mislocalizations were observed when comparing the apparent locations of pre- and post- saccadic probes, indicating that each line was shifted relative to the pre-saccadic goal. Together, these results are consistent with previously reported mislocalizations following conjugate target steps, and demonstrate novel dichoptic visual errors following oculomotor adaptation.
Meeting abstract presented at VSS 2018
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