The disappearance of foveal and nonfoveal stimuli: Decomposing the gap effect

When a foveal stimulus disappears prior to the appearance of a peripheral t arget, saccadic reaction times (RTs) are reduced. We compared this gap effe ct for foveal and nonfoveal stimuli when a highly predictive auditory warni ng signal was or was not presented. Without a tone, there was a gap effect for both foveal and nonfoveal stimuli; with a tone, there was a gap effect for foveal but not for nonfoveal stimuli. Highly predictive warning tones a lso modulated the gap effect in a manner that seemed to reflect top-down re lease of ocular inhibition. We argue that the gap effect therefore consists of three components: (a) warning effects; (b) release of ocular inhibition due to the disappearance of a foveal stimulus; and (c) release of ocular i nhibition due to top-down processes.