Abstract
To maintain gaze stability, the oculomotor system needs to correct fixational errors that may emerge subsequent to an eye blink. It has been shown that artificially induced fixation errors, when a target is displaced by a consistent amount during an eye blink, lead to an automatic correction of gaze during the blink, a process termed ‘blink adaptation’ (Lau & Maus 2018; Maus et al. 2017). In this experiment, we check if a similar corrective mechanism occurs for errors induced by displacing the target in depth during an eye blink. Participants were asked to fixate on a dot, viewed stereoscopically through 3D shutter glasses. After each blink, the binocular disparity of the dot was either increased or decreased, in separate blocks, by 0.5 degrees. Blink-induced fixation error was measured separately for each eye as the difference between the last stable gaze position prior to blink onset and the first stable gaze position after the blink, using an EyeLink 1000+ eye tracker. Fixation errors for the adaptation phase were compared to baseline measurements, where the target remained unchanged across a blink. We found that participants recalibrated their gaze for both conditions, with more automatic vergence eye movements occurring during the blink in the direction required to correct for the dichoptic step of the target. This corrective effect was generally larger for the condition with increasing disparity as compared to decreasing disparity. These results are consistent with earlier findings by Lau & Maus (2018), who showed that blink adaptation more effectively corrects errors requiring temporal as compared to nasal eye movements across eye blinks. This points to a common mechanism underlying blink adaptation for conjugate as well as dichoptic target steps.