The Mechanism Of Inhibition Of Return Triggered By The Masked Cue

At any single moment, there is so much information bombarding us. Weneed to choose relevant ones while filtering out others. Attention helps us to dothis every day, which can be guided in top-down or bottom-up pattern. Posner andCohen (1984) using the spatial cuing paradigm studied uninformative exogenouscue could modulate attention and affected the target appeared at the same locationas the cue. When the SOA (Stimulus Onset Asynchrony) was short, reaction timefor target presented at cued location was faster than it appeared at oppositelocation. While SOA was longer than250ms, slower response to the targetpresented at cued (inhibited) location was been found. The effect was calledinhibition of return (IOR). Subthreshold inhibition of return refers to the IORtriggered by invisible cue that can not be reported. Section1focused on whetherthere is inhibition of return triggered by masked invisible cue, by investigatingthat the dual attentional orienting could be induced by the masked cue or not.Using the spatial cuing paradigm, Exp.1aimed at found the optimal parametersfor the masked cue to make it invisible. Subsequently, we manipulated multipleSOA and asked participants to detect the target (Exp.2) and discriminate the colorof the target (Exp.3). We found that the invisible cue could induce an IOR at570ms of SOA in detection task (Exp.2), whereas the facilitation effect(SOA=570ms) was followed an inhibition effect (SOA=770ms) in colordiscrimination task. The results suggested that there was inhibition of returntriggered by masked cue. Section2aimed at investigating the mechanism ofinhibition of return triggered by masked cue. We combined the cue-targetparadigm with the Stroop task, in which subjects should report the print color ofthe color-word. Using the high temporal resolution of event-related potentialstechnique, N1and N450were been analysized to investigate the effect of maskedcue on sensory or perceptual processing and conflict resolving related processingof target. We found that, behaviorally, mean reaction time of the neutral targetwas longer at previously cued locations, and the Stroop effect was larger inuncued conditions. Electrophysiologically, the conflict related N450differencenegative waveform and N1component relating to early visual processing wereboth greater at uncued locations. These results indicated that regardless ofawareness, a spatial uninformative cue could induce inhibition of return and affect the Stroop interference, and might suggest that attention induced by amasked invisible cue could affect the stimuli appearing at cued locations, not onlyat the early visual processing stage but also at the late conflict resolving stage.According to the two sections’ results, we got conclusions that the maskedinvisible cue could induce the exogenous spatial attentional orienting dual effect(facilitation effect and inhibition effect), thus there must be subthresholdinhibition of return. Consistent with the mechanism of inhibition of attention, thesubthreshold inhibition return was caused by inhibiting attention.