A typkal trial of this masking experiment in\·olves. in quick succession. presentation of five letters. evocation of an eye mowment. and presentation of a spatially localized mask. either a visual-pattern mask or a metacontrast ring. The effect of the mask is to suppress the report of the letter that stimulates the same retinal location, even though the mask appears to cO\'er or surround the letter whose position in real space it shares. "-tasking is. however. weaker when the eyes move than when they do not. An auxiliary experiment suggests that the spatial aspects of observable (reportable by S) stimulus persistence are unaffected by eye movements. and therefore that observable persistence differs from that susceptible to masking.