Contextual effect on visual word recognition:Evidences from the ERPs studies
| Autor: | Yo-Ning Liu, 劉又寧 |
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| Rok vydání: | 2009 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 97 Current ERP/MEG studies showed controversial evidences on WHEN and HOW the contextual information modulates the visual word recognition. On the one hand, some studies suggested that the early processing (within 200 ms of visual word presentation) of lexical entries included semantic and phonological properties by demonstrating the semantic or lexicality effects on early ERP components (such as N1 and P200) and supported the interactive activation model. On the other hand, theories such as the modular model or those associated with Dehaene and colleagues (Dehaene et al.,2005 ) suggested that early processing of visually presented words involved bottom-up visual feature detection leading to visual word-form recognition, but not necessarily access to the semantic lexicon with the early stage of lexical access. The present study aims to address this issue by examining the effects of word frequency and contextual predictability (cloze probability of the target word embedded in the sentence) on N1, P200 and N400 components which have been related to various cognitive operations on the early visual processing, perceptual decoding and semantic processing. The data showed a significant predictability-by-frequency interaction at the anterior N1 component. The predictability effect, where the low predictability words elicited more negativity N1 than high predictability words, was only found in reading high frequency word. There was a significant predictability effect at P200, in which the low predictability words elicited less positive amplitudes than high predictability words. The N400 revealed a significant predictability effect; low predictability words elicited greater N400 than high predictability ones, but this effect did not interact with frequency. In experiment 2, the contextual predictability (high cloze probability, low cloze probability) and the orthographic similarity (orthographically identical, orthographically similar, orthographically dissimilar) was manipulated. The data showed a significant interaction at anterior N1 component. The orthographically identical words elicited more negativity in anterior N1 than the orthographically similar / dissimilar did, whereas this orthographic effect was not found in the low predictability words. There was also a significant predictability effect at P200 which was found in experiment 1. The predictability-by-orthographic similarity interaction was significant at N400. The results of two experiments suggest that the temporal dynamics of contextual information affects the visual word recognition. The visual-feature detection or the orthographic activation was facilitated by contextual information in the early stage. The contextual effect at N400 reflects the facilitation of semantic integration in the late stage of visual word recognition. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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