How and when accentuation influences temporally selective attention and subsequent semantic processing during on-line spoken language comprehension: an ERP study.

An event-related brain potentials (ERP) experiment was carried out to investigate how and when accentuation influences temporally selective attention and subsequent semantic processing during on-line spoken language comprehension, and how the effect of accentuation on attention allocation and semantic processing changed with the degree of accentuation. Chinese spoken sentences were used as stimuli. The critical word in the carrier sentence was either semantically congruent or incongruent to the preceding sentence context. Meanwhile, the critical word was de-accented (DeAccent), generally accented (Accent), or greatly accented (GreatAccent). Results showed that, relative to semantically congruent words, the semantically incongruent word elicited a parietal-occipital N400 effect in the Accent condition and a broadly distributed N400 effect in the GreatAccent condition; however, no significant N400 effect was found in the DeAccent condition. Further onset analysis found that the N400 effect in the GreatAccent condition started around 50ms earlier than that in the Accent conditions. In addition, in the GreatAccent condition, the incongruent words also elicited an early negative effect in the window latency of 110-190ms after the acoustic onset of the critical word. The results indicated that, during on-line speech processing, accentuation can rapidly modulate temporally selective attention and consequently influence the depth or the speed of subsequent semantic processing; the effect of accentuation on attention allocation and semantic processing can change with the degree of accentuation gradually.