Martin Clara D, Nazir Tatjana, Thierry Guillaume, Paulignan Yves, Démonet Jean-François
INSERM U455, Hôpital Purpan, F-31059, Toulouse Cedex, France.
Brain Res. 2006 Jul 7;1098(1):153-60. doi: 10.1016/j.brainres.2006.04.097. Epub 2006 Jun 13.
Most classical models of visual word recognition are based on sequentially organized levels of representation and involve feedback mechanisms to various extents. In this study, we aim at clarifying which of the early processing stages of visual word recognition are modulated by top-down lexical effects. We studied the identification of letters embedded in briefly presented words (e.g., TABLE) and illegal nonwords (e.g., GTFRS) using event-related potentials (ERPs). Participants were involved in the Reicher-Wheeler paradigm: they were asked to indicate which of two letters displayed above and below a string of hashes was flashed immediately before at fixation within a letter string, which was either a word or a nonword. Event-related potentials were significantly modulated by the lexical status of stimuli around 200 ms after stimulus onset, i.e., in the peaking window of the N1 component. In light of our results, we propose that visual word form representations can constrain letter identification at a prelexical stage i.e., during the extraction of letter-shape information. In addition, we show that this facilitatory top-down effect is sensitive to stimulus exposure duration.
大多数视觉单词识别的经典模型基于顺序组织的表征层次，并在不同程度上涉及反馈机制。在本研究中，我们旨在阐明视觉单词识别的早期处理阶段中哪些受到自上而下的词汇效应的调节。我们使用事件相关电位（ERP）研究了嵌入在短暂呈现的单词（如TABLE）和非法非单词（如GTFRS）中的字母识别。参与者参与了赖克-惠勒范式：他们被要求指出在一串哈希符号上方和下方显示的两个字母中，哪一个在字母串（单词或非单词）的注视点处之前立即闪烁。刺激开始后约200毫秒，即N1成分的峰值窗口，事件相关电位受到刺激词汇状态的显著调节。根据我们的结果，我们提出视觉单词形式表征可以在词汇前阶段，即在字母形状信息提取过程中，约束字母识别。此外，我们表明这种促进性的自上而下效应对刺激暴露持续时间敏感。
