A "blanking effect" for surface features: Transsaccadic spatial-frequency discrimination is improved by postsaccadic blanking.

Abstract

Although saccadic eye movements occur frequently—about three or four times a second—humans are astonishingly blind to transsaccadic changes. Locational displacements of the saccade target of up to 2 deg of visual angle, and even large changes of a visual scene, can go unnoticed. For a long time, this insensitivity was ascribed to deficits in transsaccadic memory: Only a coarse, (spatially) imprecise representation would be retained across a saccade. This assumption was contradicted by Deubel's and Schneider's (Behavioral and Brain Sciences 17:259-260, 1994) striking finding that locational discrimination performance across a saccade is greatly improved by inserting a short postsaccadic blank. Surprisingly, the question of whether blanking effects occur also for other forms of transsaccadic changes (i.e., surface-feature changes) has been widely ignored. We tested this question by means of a transsaccadic change in spatial frequency. Postsaccadic blanking facilitated spatial-frequency discrimination, but to a smaller amount than the usual blanking effects obtained with locational displacements. This finding bears important implications for models of visual stability and transsaccadic memory.