语篇语境对句子理解的影响：来自N400的证据

N400作为语义违反的特异性ERP组分,其波幅反映了语义整合加工过程的难度,因此可将其作为研究语篇语境意义建构过程的一项重要指标。语篇语境可分为语言语境和非语言语境。前人一系列基于语篇水平的N400研究表明,从语义的角度上看,语言语境对句子理解具有制约和协调作用,其机制涉及词汇语义启动、场景适宜性、文字内容信息以及因果推理等方面;非语言语境对句子理解具有制约和补充作用,但其机制尚不明确。两种不同来源的语义信息在实时理解中是同时得到加工的     

双语即时切换下非目标语言语音和语义的激活状态

本研究采用双语即时切换范式, 探讨非熟练中英双语者在对目标语言(启动词)语音或语义的加工过程中非目标语言的激活状态。实验1设置了与启动词的翻译对等词存在语音相关或无关的两类配对词, 要求被试进行语音判断任务, 结果表明, 不论哪种切换条件, 两类配对词在反应时和P200成分上都没有差异, 说明目标语言在语音加工过程中非目标语言的语音层面没有得到自动激活, 从而没有产生启动效应。实验2则设置了语义相关和无关配对词, 并进行语义判断任务, 结果在两种切换条件下都发现明显的语义启动效应及N400差异, 说明非目标语言在语义层面上有得到自动激活, 但激活的程度表现出切换方向上的不一致, L1-L2切换下的语义启动量要明显大于L2-L1, 并且L1-L2的N400差异主要表现在前部脑区, 持续时间更久, 而L2-L1的N400差异主要表现在后部脑区, 但持续时间较短, 表明对于非熟练的双语者来说, 不同切换方向下对共享语义表征的激活加工是不一样的。     

任务与字频对汉字情绪启动反转效应的影响

本研究使用ERP技术对比了效价判断与真假字判断两种任务形式下的汉字情绪启动效应。结果发现,在效价判断任务中高频目标字出现情绪启动的反转效应,效价不一致比一致条件下反应时短,诱发了较大的P200;低频目标字出现情绪启动的一致性效应,效价一致比不一致条件下反应时短,诱发了较大的P200与N400。真假字判断任务中高频和低频目标字均出现情绪启动的一致性效应。情绪启动的反转效应依赖于刺激材料的可通达性与注意导向,启动字与目标字的反应竞争关系导致了情绪启动的反转效应。     

句子阅读理解过程中句意的建构时间

一般语言学理论认为, 在句子阅读理解过程中, 句子意义建构是基于词汇语义整合的, 其反映在N400之上, 开始于词语呈现后约250 ms。然而, 近年关于语义P600效应的研究却提示句意建构可能存在多通道或方式, 读者甚至可能在N400反映的加工出现之前就已建立了初步句意。为探明在句子阅读理解过程中是否存在比N400反映的加工更早的句意建构, 以及如果存在这样的句意建构, 其是从何时开始的, 本研究开展了四个实验。实验1发现被试在句末双字词呈现200 ms后已将其联系到上文语义表征而建立了句意, 提示句意建构开始于N400反映的加工出现之前。实验2与3进一步发现, 读者开始建立句意的时间约在句末词呈现了150 ms之时。实验4排除了实验1~3效应的其他一些可能解释, 提升了实验1~3结果的可靠性。总体上, 本研究提示：在句子阅读理解过程中, 读者在句末双字词呈现了约150 ms之时就已建立了句意; 可能存在比N400反映的加工更早的句意建构。     

刻板印象激活的无意图性及其大脑神经活动特征

采用启动Stroop范式, 对刻板印象激活的无意图性及其大脑神经活动特征进行了探讨。操纵了启动和“无启动”条件以及与启动所激活的刻板印象一致、冲突和无关的3类靶子词, 记录了36名大学生被试对靶子词进行颜色判别的行为反应和脑电图(EEG, electroencephalogram)。结果发现：(1)“无启动”条件下对3类靶子的反应时基本一致; 启动条件下对一致靶子做出颜色判别的反应时显著快于对冲突靶子的, 对无关靶子的反应时介于两者之间。(2)“无启动”条件下无关靶子诱发的N400波幅最大--显著大于一致和冲突靶子诱发的, 后两者诱发的N400无差异; 启动条件下一致靶子诱发的N400波幅显著小于冲突和无关靶子诱发的N400波幅, 无关靶子诱发的N400波幅也小于冲突靶子诱发的N400波幅。这表明刻板印象激活是一个发生在知觉后加工阶段的具有无意图性的自动化加工过程, 刻板印象激活效应具有抑制冲突信息加工同时促进一致信息加工的“双刃剑”模式, N400可以作为考察这一认知过程特征的电生理学指标。     

世界知识在句子理解中的整合时程

Hagoort等(2004)应用背离范式发现世界知识和单词意义在句末的整合是同时进行的。本研究将背离信息提前到句首短语中,旨在探讨世界知识在句子阅读过程中被整合的时程特征。实验采用四词句子为材料,其中第二个词（目标词）含有单词意义或世界知识背离信息,记录并比较被试在阅读后三个词时诱发的脑电变化。结果发现：与正确句子比较,无论是单词意义背离还是世界知识背离,背离目标词均引发出经典的N400,二者在峰值时间和始潜时上无显著差异,但世界知识背离信息诱发的N400波幅值相对较小。句中的后继单词不再诱发类似的N400;但到句子结尾,两类含有背离信息句子的句末正常单词又诱发出类似N400的一个负波。结果提示,在句子理解过程中,世界知识的整合与单词意义的整合相似,可能是随着句子理解过程即时进行的,整合的结果不影响后继信息的加工;但到了句末,读者在对整个句子内容作真实性判断时会对先前进行过的整合再进行考察。     

句子语境中汉语词汇歧义消解的ERP研究

采用ERP方法,考察了汉语词汇歧义消解中句子语境作用的时间进程及大脑活动。目标词与句子语境存在一致、不一致、无关控制等3种关系。结果显示:(1)一致与不一致条件下N400的平均波幅均显著低于无关控制条件;(2)SOA为200毫秒时产生的N400平均波幅的幅度显著高于SOA为1000毫秒的条件;(3)N400的平均波幅及潜伏期均表现出左半球显著高于右半球的特点。实验结果支持词汇歧义消解的模块化观点,体现了大脑两半球语言功能的不对称性。     

Big brown dog or brown big dog? An electrophysiological study of semantic constraints on prenominal adjective order

Event-related brain potentials (ERPs) were recorded while participants read and made acceptability judgments about sentences containing three types of adjective sequences: (1) normal sequences--e.g., Jennifer rode a huge gray elephant; (2) reversed sequences that violate grammatical-semantic constraints on linear order--e.g., *Jennifer rode a gray huge elephant; and (3) contradictory sequences that violate lexical-semantic constraints on compositionality--e.g., *Jennifer rode a small huge elephant. Relative to the control condition, the second adjective elicited a reduced N400 and an enhanced P600 in both the reversal condition and the contradiction condition. We present several alternative accounts of these two effects, but favor an interpretation which treats them as reflecting semantic and syntactic aspects of a temporary reanalysis of the adjective order construction. Furthermore, relative to the control condition, the final noun elicited a robust N400 in the contradiction condition but not in the reversal condition. We suggest that this effect indexes the full registration of the lexical-semantic incompatibility of the two adjectives in the contradiction condition. Finally, we discuss how all of these findings fit into the broader context of recent ERP studies that have reported atypical N400s and robust P600s in response to certain types of semantic anomalies.     

An ERP investigation of conditional reasoning with emotional and neutral contents

In two experiments we investigate conditional reasoning using event-related potentials (ERPs). Our goal was to examine the time course of inference making in two conditional forms, one logically valid (Modus Ponens, MP) and one logically invalid (Affirming the Consequent, AC). We focus particularly on the involvement of semantically-based inferential processes potentially marked by modulations of the N400. We also compared reasoning about emotional and neutral contents with separate sets of stimuli of differing linguistic complexity across the two experiments. Both MP and AC modulated the N400 component, suggesting the involvement of a semantically-based inferential mechanism common across different logical forms, content types, and linguistic features of the problems. Emotion did not have an effect on early components, and did not interact with components related to inference making. There was a main effect of emotion in the 800–1050 ms time window, consistent with an effect on sustained attention. The results suggest that conditional reasoning is not a purely formal process but that it importantly implicates semantic processing, and that the effect of emotion on reasoning does not primarily operate through a modulation of early automatic stages of information processing.     

Event-related potentials indicate context effect in reading ambiguous words

The aim of the study was a comparison of lexical and contextual factors in understanding ambiguous words in German. First, a sample of native speakers selected 56 words having maximally strong differences between a dominant and a subordinate meaning. After this, another sample from the same population was visually presented with sentences that activated dominant or subordinate meanings of the words and were accompanied by probes associated with dominant or subordinate meanings. This resulted in a crossed design with two factors: sentence dominant vs. sentence subordinate and probe dominant vs. probe subordinate. An analysis of event-related brain potentials revealed a large, long-lasting and highly-significant N400 wave whenever the meaning of the probe was incongruent with the meaning of the sentence and the lack of this wave whenever the two meanings were congruent. In the typical N400 space and time, the effect was independent of whether the lexical word meaning was dominant or subordinate. At other sites and times, however (e.g., at lateral frontal electrodes F7/F8, and after 700 ms), the congruence effect was significant after dominant sentences only. The data indicate that lexical factors have a rather limited influence on the activation of a particular meaning of ambiguous words. A strong context can virtually override even a very strong difference in the preference for different meanings.