ERP analyses of task effects on semantic processing from words (original) (raw)

Getting the gist is not enough: an ERP investigation of word learning from context

We examined contextual effects on word learning using event-related brain potential (ERP) methodology. Adult participants first read known and unknown novel words in strongly and weakly constraining sentence contexts. Then, to assess acquisition of word meaning, they rated the plausibility of probe sentences in which these same words served as objects of a transitive verb. Plausibility effects were observed in the N400 component to the verb only when the upcoming novel word object had initially appeared in a strongly constraining context. These results demonstrate differences in electrical brain activity related to rapid, one-shot contextual word learning.

Word-to-text integration: Message level and lexical level influences in ERPs

Neuropsychologia, 2014

Although the reading of connected text proceeds in a largely incremental fashion, the relative degree to which message level and lexical level factors contribute to integration processes across sentences remains an open question. We examined the influence of both factors on single words using event-related potentials (ERPs). Word pairs with either strong or weak forward association strength were critical items: embedded as coreferential words within two-sentence passages in a text comprehension task, and as isolated word pairs in a word meaning judgment task. While the N400 ERP component reflected an effect of forward association strength on lexico-semantic processing in the word task (i.e., reduced N400 amplitudes were seen for strongly associated pairs relative to weakly associated pairs), in the comprehension task, passages embedded with any associated word pairs elicited reduced N400 amplitudes relative to coherent baseline passages lacking one of the critical words. These comprehension effects reflect responses from the highest skilled comprehenders. The results demonstrate the effects of message level factors, and reading abilities, on the processing of single words.

The ERP response to the amount of information conveyed by words in sentences

Reading times on words in a sentence depend on the amount of information the words convey, which can be estimated by probabilistic language models. We investigate whether event-related potentials (ERPs), too, are predicted by information measures. Three types of language models estimated four different information measures on each word of a sample of English sentences. Six different ERP deflections were extracted from the EEG signal of participants reading the same sentences. A comparison between the information measures and ERPs revealed a reliable correlation between N400 amplitude and word surprisal. Language models that make no use of syntactic structure fitted the data better than did a phrase-structure grammar, which did not account for unique variance in N400 amplitude. These findings suggest that different information measures quantify cognitively different processes and that readers do not make use of a sentence's hierarchical structure for generating expectations about the upcoming word.