The spatial gradient of visual masking by object substitution

A mask that has a common onset but delayed offset with the target produces substitution masking, which can be distinguished from pattern masking and metacontrast masking. This study tests the spatial properties of substitution masking: specificity to the target location and asymmetry to the central and the peripheral sides of the target. Results revealed that substitution declined gradually as the mask moved away from the target. Masking was stronger and its gradient declined more slowly as the eccentricity of the target increased. Substitution was asymmetric, stronger for peripheral than central masks. Results are consistent with a refined model of object substitution based on reentrant visual processing.