The fractionation of spoken language understanding by measuring electrical and magnetic brain signals

摘要

This paper focuses on what electrical and magnetic recordings of human brain activity reveal aboutrnspoken language understanding. Based on the high temporal resolution of these recordings, a finegrainedrntemporal profile of different aspects of spoken language comprehension can be obtained.rnCrucial aspects of speech comprehension are lexical access, selection and semantic integration.rnResults show that for words spoken in context, there is no ‘magic moment’ when lexical selectionrnends and semantic integration begins. Irrespective of whether words have early or late recognitionrnpoints, semantic integration processing is initiated before words can be identified on the basis of thernacoustic information alone. Moreover, for one particular event-related brain potential (ERP)rncomponent (the N400), equivalent impact of sentence- and discourse-semantic contexts is observed.rnThis indicates that in comprehension, a spoken word is immediately evaluated relative to the widestrninterpretive domain available. In addition, this happens very quickly. Findings are discussed thatrnshow that often an unfolding word can be mapped onto discourse-level representations well beforernthe end of the word. Overall, the time course of the ERP effects is compatible with the view that therndifferent information types (lexical, syntactic, phonological, pragmatic) are processed in parallel andrninfluence the interpretation process incrementally, that is as soon as the relevant pieces of informationrnare available. This is referred to as the immediacy principle.