MRC Cognition and Brain Sciences Unit, Cambridge, UK.
Department of Psychology, University of Stirling, UK.
Neuropsychologia. 2015 Feb;68:126-38. doi: 10.1016/j.neuropsychologia.2015.01.008. Epub 2015 Jan 8.
Theoretical linguistic accounts of lexical ambiguity distinguish between homonymy, where words that share a lexical form have unrelated meanings, and polysemy, where the meanings are related. The present study explored the psychological reality of this theoretical assumption by asking whether there is evidence that homonyms and polysemes are represented and processed differently in the brain. We investigated the time-course of meaning activation of different types of ambiguous words using EEG. Homonyms and polysemes were each further subdivided into two: unbalanced homonyms (e.g., "coach") and balanced homonyms (e.g., "match"); metaphorical polysemes (e.g., "mouth") and metonymic polysemes (e.g., "rabbit"). These four types of ambiguous words were presented as primes in a visual single-word priming delayed lexical decision task employing a long ISI (750 ms). Targets were related to one of the meanings of the primes, or were unrelated. ERPs formed relative to the target onset indicated that the theoretical distinction between homonymy and polysemy was reflected in the N400 brain response. For targets following homonymous primes (both unbalanced and balanced), no effects survived at this long ISI indicating that both meanings of the prime had already decayed. On the other hand, for polysemous primes (both metaphorical and metonymic), activation was observed for both dominant and subordinate senses. The observed processing differences between homonymy and polysemy provide evidence in support of differential neuro-cognitive representations for the two types of ambiguity. We argue that the polysemous senses act collaboratively to strengthen the representation, facilitating maintenance, while the competitive nature of homonymous meanings leads to decay.
理论语言学对词汇歧义的解释区分了同形异义词和多义词。同形异义词是指具有相同词汇形式但含义无关的词，而多义词是指含义相关的词。本研究通过询问同形异义词和多义词在大脑中的表示和处理是否不同，来探索这一理论假设的心理现实性。我们使用 EEG 研究了不同类型的歧义词的意义激活时间进程。同形异义词和多义词又各自分为两类：不平衡同形异义词（如“coach”）和平衡同形异义词（如“match”）；隐喻多义词（如“mouth”）和转喻多义词（如“rabbit”）。这四种类型的歧义词作为视觉单字启动延迟词汇决策任务中的启动词，采用长 ISI（750 毫秒）。目标词与启动词的一个含义相关，或不相关。相对于目标词起始的 ERP 表明，同形异义和多义词之间的理论区别反映在 N400 脑反应中。对于同形异义词的目标词（不平衡和平衡的同形异义词），在这么长的 ISI 下，没有效果存活下来，这表明启动词的两个含义都已经衰减。另一方面，对于多义词的启动词（隐喻和转喻），都观察到了主要和次要意义的激活。同形异义和多义词之间观察到的处理差异为两种类型的歧义提供了支持神经认知表示不同的证据。我们认为，多义词的意义共同作用，加强了表示，促进了维持，而同形异义词的竞争性质则导致了衰减。
