Abstract
Saccadic adaptation is a regulatory mechanism controlling the amplitude of saccades. It is driven by post-saccadic information about the error made by the saccade.
In a typical adaptation paradigm, a static displacement of the visual target during the perceptual inhibition period of the saccade serves as inducer of the post-saccadic error. The post-saccadic error is then the difference between the landing position and the target position.
Here we present evidence that saccadic error information can be calculated without the actual existence of a luminance or color defined target. In our study saccades were adapted by a second order motion stimulus. Subjects made saccades over a static noise pattern background. The fixation location and the saccade target position were successively indicated by a red frame (2 by 2 deg). When the subject made the saccade the target frame was extinguished. Thus, after the saccade only the background pattern was visible. 100 ms after saccade offset, clearly separating post-saccadic motion information from the saccade, a cutout of the background noise pattern of the target frame moved with a high velocity of 50 deg/sec either in or against the direction of the saccade (in separate conditions) thus producing second order motion. In a standard comparison of unadapted and adapted trials saccadic amplitude modifications were found.
We therefore present evidence that visual motion information is also used to calculate saccadic errors.
Meeting abstract presented at VSS 2012