Vergara-Martínez Marta, Comesaña Montserrat, Perea Manuel
Estructura de Recerca Interdisciplinar de Lectura (ERI-Lectura), Universitat de València, València, Spain.
Human Cognition Lab, CIPsi, School of Psychology, University of Minho, Braga, Portugal.
Cogn Affect Behav Neurosci. 2017 Jun;17(3):461-474. doi: 10.3758/s13415-016-0491-7.
Behavioral experiments have revealed that words appearing in many different contexts are responded to faster than words that appear in few contexts. Although this contextual diversity (CD) effect has been found to be stronger than the word-frequency (WF) effect, it is a matter of debate whether the facilitative effects of CD and WF reflect the same underlying mechanisms. The analysis of the electrophysiological correlates of CD may shed some light on this issue. This experiment is the first to examine the ERPs to high- and low-CD words when WF is controlled for. Results revealed that while high-CD words produced faster responses than low-CD words, their ERPs showed larger negativities (225-325 ms) than low-CD words. This result goes in the opposite direction of the ERP WF effect (high-frequency words elicit smaller N400 amplitudes than low-frequency words). The direction and scalp distribution of the CD effect resembled the ERP effects associated with "semantic richness." Thus, while apparently related, CD and WF originate from different sources during the access of lexical-semantic representations.
行为实验表明，出现在多种不同语境中的单词比出现在少数语境中的单词反应更快。尽管已发现这种语境多样性（CD）效应比词频（WF）效应更强，但CD和WF的促进作用是否反映相同的潜在机制仍存在争议。对CD的电生理相关性进行分析可能会为这个问题提供一些线索。本实验首次在控制词频的情况下，研究了高CD词和低CD词的事件相关电位（ERP）。结果显示，虽然高CD词比低CD词产生更快的反应，但其ERP在225 - 325毫秒时比低CD词表现出更大的负波。这一结果与ERP词频效应的方向相反（高频词引发的N400波幅比低频词小）。CD效应的方向和头皮分布类似于与“语义丰富性”相关的ERP效应。因此，虽然CD和WF显然相关，但在词汇语义表征的获取过程中，它们源自不同的来源。
