The effect of individual differences of working memory on the lexical access : Topographical analysis of ERP

本研究旨在探讨工作记忆的个体差异对词汇通达的影响。记录事件相关电位(ERP)和反应时(RT)以探讨词汇通达过程的脑机制，并采用阅读广度测验(RST)测量工作记忆的个体差异。将被试分为高广度组(RST)和低广度组(RST)，测量词汇刺激效应，比较两组启动效应的个体差异。实验采用语义相关词对和不相关词对两种形式，相关词对的反应时降低，不相关对的词对反应时增加，表现为词汇通达的加速和抑制；事件相关电位呈现P300和N400两个典型成分。P300在相关条件下波幅增加。然而，在非相关状态下，N400的波幅增加。此外，地形图显示高跨度组和低跨度组之间存在地形图的差异。对于高跨度受试者，N400和P300在无关条件下定位于额区。

The purpose of this research was to investigate the effect individual differences of working memory on the lexical access. Event related potential (ERP) and reaction time (RT) were recorded to investigate the brain mechanism of lexical access processes.Individual differences of working memory were measered with use of reading span test (RST). Subjectw were divided into two groups ; high score of RST (high span group) and low score of RST (low span group).Piming effect of words was measured and the individual difference of priming effect was compared between the group. Two kinds of pairs of words were used ; the semantically related pair and unrelated pair.The RT decresed with related pair and RT increased with unrelated pair, which showed the acceleration and inhibition of lexical access of word each.The ERP showed two typical components of P300 and N400. P300 increase in it's amplitude in the related condition. N400, however, increased in it's amplitude in the un-related condition. Moreover, topographyical mapping showed that there were mapping differences between the high span group and low span group. For high span subjects, the N400 and P300 localized in the frontal areas in the unrelated condition.