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Moon, Heechun
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Middle Tennessee State University
The pattern of stressed and unstressed syllables in spoken language provides rhythmic cues that are known to influence speech segmentation and language acquisition. Research using the event-related potential (ERP) method also shows that language comprehension is facilitated when spoken utterances have a highly regular stress pattern. In addition, an increasing body of evidence suggests that sensitivity to speech rhythm is linked to early literacy acquisition and that information regarding word stress patterns may be automatically retrieved during silent reading. The current ERP study was thus aimed at examining whether rhythmic regularity facilitates reading comprehension during silent reading. To this end, written sentences were created, in which the sixth word, the critical word, was either semantically expected or unexpected. The critical word was always bi-syllabic and stressed on the first syllable. In addition, the implicit rhythm generated by the stress pattern leading up to the critical word was either regular or irregular. EEG was recorded from participants while participants performed a semantic judgment task on the written sentences. ACT reading scores were also collected and used as a reading comprehension measure. Results of cluster-based permutation tests showed that Semantically Unexpected words elicited an increased centro-frontal N400 effect in both Rhythmically Irregular and Rhythmically Regular contexts. A direct comparison of the N400 effect elicited in the two rhythmic contexts revealed that it was larger and lasted longer in the Rhythmically Irregular condition than the Rhythmically Regular condition. In addition, sensitivity to implicit speech rhythm (defined as the difference between the N400 effects in the Rhythmically Regular and Rhythmically Irregular conditions) was positively correlated with reading comprehension skills. Overall, the present results support the idea that information about the stress pattern of words is automatically retrieved during silent reading, and that a regular rhythmic context may facilitates lexico-semantic integration by providing a temporal grid allowing for better predictions of upcoming linguistic units. These findings thus provide neurophysiological evidence for the Implicit Prosody Hypothesis proposing that readers build a prosodic representation of the text during silent reading. The present findings also further support the idea that speech rhythm sensitivity plays an important role in the development of reading skills.
ERP, Implicit Prosody Hypothesis, N400, Reading comprehension, Speech rhythm