Attentional Capture Is Contingent On Attentional Control Set For Meaning

A salienct stimulus attracts attention involuntarily. This phenomenon is named asattentional capture, and the salience of stimuli is named as singleton. There is large amount ofevidence showing that attentional capture is conditional and modulated by top-down factors.However, previous work has mainly focused on perceptual processing. There is also evidenceshowing that selective attention is influenced by semantic processing, search strategies andtask context. Here we focused on the effect of semantic processing on attentional capture bymanipulating cue-target relevance, search strategies and task context. Using a standard visualsearch task, we attempted to provide systematically evidence on (1) whether attentionalcapture was modulated by semantic processing,(2) how semantic, perceptional relevance andsearch strategies guided attentional capture,(3) the effect of asymmetry of visual fields insemantic contingent attention capture, and (4) how semantic contingent attention capture wasinfluenced by social information.A modified spatial cueing paradigm was employed in the current thesis. In a trial, afixation screen was presented for500ms, followed by an uninformative cue which appearedfor100ms. Then a fixation screen was displayed for100ms, followed by a target screendisplayed1000ms for character target or500ms for color target. Participants had to make ajudgment for the gap orientation of a target square while ignoring other distractors. Targetswere identified by characters or color and randomly presented at the cued or non-cuedlocations, making cues valid or invalid. The effect of attentional capture was measured by thedifferential scores between the responses to the invalid and valid conditions-that is, slowerresponses to invalid contrasting to those to valid targets. For event-related brain potentialsstudies, N2pc component was used as the indicator of attentional capture. By establishingperceptional relevance, semantic relevance between cue and target, search strategies adoptedand task context, we assessed the semantic contingent attentional capture and the interactionwith other influencing factors.The analyses showed that there was the effect of attentional capture when cue and targetwere semantic relevant and the cues congruent with semantic attentional control settingattracted attention (Study1). The capture effect was not observed when the cue and the targetwere irrelevant whilst no search strategy was adopted or feature search mode was induced, tocontrast, the data demonstrated the capture effect when singleton detection mode was used,and when the semantic relevance or the perceptional relevancebetween the cue and the targetwas established. However, the capture effects induced by singleton detection mode, as well as by semantic relevance were eliminated when perceptional relevance occurred (Study2). Thedifference of cue-induced N2pc in parietal-occipital sites was observed as a function ofcue-target semantic congruency when cues occurred in right visual field, but the N2pc effectwas eliminated when the cues occurred in left visual field. The reaction times did not showthe effect of visual field asymmetry (Study3), and there was no semantic contingentattentional capture when self-related information appeared as either the cues or the targets(Study4).It was concluded that (1) the semantic association between cue and target was able tomodulate the magnitude of attentional capture, but the effect exclusively occurred when therewas no perceptional relevance between cue and target,(2) the perceptional relevance betweencue and target was more pronounced to drive attentional capture than the semantic linksbetween cue and target and search strategies,(3) attentional capture was modulated by thesearch strategy-singleton detection mode, but not by feature search mode after controllingthe perceptional relevance and the semantic relevance between cue and target,(4) thesemantic contingent attentional capture revealed right field advantage, indicating theleft-hemisphere bias of semantic involuntary attention shift, and (5) there was no semanticcontingent attentional capture when social salience of stimuli was induced. The resultsindicated the effective modulation of social information to semantic involuntary attentionorienting.