Abstract
Introduction: Saccade adaptation not only influences saccade amplitude, but can also alter visual perception: it can induce mislocalization of flashed visual targets, presented immediately before saccade execution. Saccade adaptation is also contextual: different gains can be maintained for the same vector depending on visuomotor context. Can perceptual mislocalizations also be context-dependent? Methods: Context was defined by circular motion direction (clockwise vs. anti-clockwise). While maintaining fixation, subjects viewed a circularly moving target. There were 4 trial types. 1- Localization-only: subjects stayed on a fixation point throughout the trial, which ended after they used a mouse cursor to localize a bar that had flashed briefly near the target. 2- Saccade-only: a go-signal (fixation point offset) elicited saccades towards the moving target. 3- Target-On: after a go-signal, but before the subsequent saccade, bars were flashed near the target, which continued moving and were visible for a short time post-saccade. After the target disappeared, subjects localized the flashed bar with the mouse cursor. 4- Target-Off: as in Target-On, but the target disappeared upon saccade onset. Contexts were interleaved throughout separate baseline and adapt sessions; the first half of each session were saccade-only trials, followed by all 4 trial types randomly interleaved. During adapt sessions, the target stepped inward or outward depending on motion direction. Results: Mislocalization in Target-on, Target-off and Localization-only tasks were significantly different for the two contexts, and these mislocalizations were proportional to the size of contextual saccade adaptation. Moreover, the mislocalization within each Target-off trial was significantly correlated with saccade amplitude, but not during the Target-on trials. Discussion: We can induce context-dependent changes in visual perception by a simple motor adaptation task, and the size of this perceptual effect depends on the size of the saccade adaptation. Remarkably, the perceptual effects transfer to non-saccade, Localization-only trials.
Meeting abstract presented at VSS 2014