Abstract
The oculomotor system re-calibrates gaze position when a fixation target changes position during blinks, although observers are unaware of the displacement (Maus et al., Current Biology 27, 445–450, 2017). This previous study only tested rightward displacements during spontaneous eye blinks. Does "blink adaptation" (BA) also occur equally for other displacement directions and for reflexive eye blinks? Participants (N = 20) observed a white dot on a black screen that repeatedly displaced by 0.7° in the same direction during each blink. Participants completed blocks of displacements in all cardinal directions (upward, downward, rightward, leftward) for voluntary blinks, and for reflexive eye blinks triggered by an air puff to the eyelid. We measured gaze positions after blinks in the right eye and assessed BA by comparing gaze positions between baseline conditions and after adaptation. Results illustrated significant BA in all directions, but also significant differences between directions: BA was largest for downward and rightward (i.e., temporal in the right eye) directions, smaller for upward and leftward (i.e., nasal). We found no within-subject differences in BA between reflexive and voluntary/spontaneous blinks, although only the rightward displacement direction showed significant BA for reflexive blinks. Adaptation to reflexive blinks was potentially contaminated by intervening voluntary blinks; the dot was only displaced during reflexive blinks. Our results add evidence that the oculomotor system re-calibrates gaze position to compensate for oculomotor errors during blinks, regardless whether these are triggered voluntarily/spontaneously or reflexively via an external stimulus. Evidence of anisotropies across different displacement directions indicates that oculomotor constraints of blink-related eye movements play a role in the effectiveness of gaze re-calibration across blinks.
Meeting abstract presented at VSS 2018