Pre-saccadic orthogonal motion and saccadic suppression of displacement

Abstract

Short disruptions of visual input are caused by saccades. As a consequence, we do not perceive displacements of objects during a saccade, which is known as Saccadic Suppression of Displacement (SSD). When was movement of the retinal image caused by the saccade and when by movement of an object? This question is solved by the process of remapping pre-saccadic object locations to the expected post-saccadic locations. With an error area of remapped coordinates the visual system takes into account that a saccade is subjective to errors. When the post-saccadic object location falls in this area, movement is attributed to the saccade. When it falls out of this area, movement is attributed to the object, a relieve in SSD is seen. Wexler and Collins (2014) found this relieve in SSD by moving out of the error area with an orthogonal step. Unreliable object information after a saccade causes relieve in SSD, but what is the effect prior to a saccade. This study considered this question by having a pre-saccadic orthogonal motion. Furthermore, we aimed to replicate the study of Wexler and Collins. In general, we hypothesize that unreliable information after a saccade can cause relieve in SSD, whereas prior to a saccade it causes high suppression. The orthogonal motion, orthogonal step and orthogonal motion plus step could not relieve SSD. This could be ascribed to greater variability in the saccadic errors. There is a larger chance of the motion being attributed to the saccade when the error area is bigger.