Abstract
Saccadic eye movements are rapid shifts of gaze that direct the fovea, from one point of interest to another. On each saccade, the entire scene streams across the retina at hundreds of degrees per second. However, this streaming is not apparent, due to a reduced visual sensitivity toward motion during saccades. We have observed that when scenes translate transsaccadically (during saccades) they are perceived as moving slower than equivalent sized intersaccadic transitions. We confirmed these findings using a magnitude estimation technique (Sadr, Allison & Vinnikov, ECVP 2007). We further explored the dependence of transsaccadic motion perception on the direction of shift in a 4AFC experiment. We examined the effect of different scene transitions relative to saccade directions both horizontally and vertically, and subjects had to indicate direction of the scene transitions if detected. Subjects sequentially fixated blinking fixation points (20o apart) indicated on each image based on horizontal or vertical saccade direction conditions. We conclude that during saccades, the magnitude of the velocity signal is attenuated as well as its detectability. Furthermore, the extent of saccadic suppression depends on the relative saccade direction and the direction of scene transition.