Abstract
Observers often do not notice when a visual target is displaced during a saccade (Bridgeman et al., 1975). Instead, if the displacement is repeated on several saccades, the oculomotor system adapts so that saccades land near the displaced target (McLaughlin, 1967). Other disruptions of the visual input may also require a recalibration of gaze. Specifically, here we test whether target displacements during blinks lead to similar adaptation of the oculomotor system. Observers were instructed to fixate a white target dot on a screen in a dark room. Gaze direction and pupil size were recorded and blinks detected in real-time. With every blink—while the lids covered the pupil—the target was displaced laterally by 0.5º (or 1.0º). To counter accumulated shifts, the target jumped to a new random location every 3-4 s. Most observers reported being unaware of displacements during blinks. After adapting for ~50 blinks, gaze positions after the blink showed significant shifts in the direction of the displacement. This automatic gaze shift persisted for several blinks after adaptation, when the target was no longer displaced. In control experiments, we simulated blinks using shutter glasses. Although the displacement occurred while the shutters were closed, observers perceived obvious apparent motion of the target. No adaptive gaze shift occurred for simulated blinks, even when they were cued with a warning tone or triggered when the observer pressed a key. Significant adaptation of gaze shifts occurred exclusively for real blinks. Target displacements during blinks can trigger automatic gaze corrections, just as they can for saccades. This mechanism might be specific to the maintenance of gaze direction across blinks, or this novel effect—along with ‘saccadic adaptation’—might be the result of a more general oculomotor adaptation mechanism evoked by intrinsically generated disruptions of the visual input.
Meeting abstract presented at VSS 2015