title: Meaningful physical changes mediate lexical-semantic integration: top-down and form-based bottom-up information sources interact in the N400.
abstract: Models of how the human brain reconstructs an intended meaning from a linguistic input often draw upon the N400 event-related potential (ERP) component as evidence. Current accounts of the N400 emphasise either the role of contextually induced lexical preactivation of a critical word (Lau, Phillips, & Poeppel, 2008) or the ease of integration into the overall discourse context including a wide variety of influencing factors (Hagoort & van Berkum, 2007). The present ERP study challenges both types of accounts by demonstrating a contextually independent and purely form-based bottom-up influence on the N400: the N400 effect for implausible sentence-endings was attenuated when the critical sentence-final word was capitalised (following a lowercase sentence context). By contrast, no N400 modulation occurred when the critical word involved a change from uppercase (sentence context) to lowercase. Thus, the N400 was only affected by a change to uppercase letters, as is often employed in computer-mediated communication as a sign of emphasis. This result indicates that N400 amplitude is reduced for unexpected words when a bottom-up (orthographic) cue signals that the word is likely to be highly informative. The lexical-semantic N400 thereby reflects the degree to which the semantic informativity of a critical word matches expectations, as determined by an interplay between top-down and bottom-up information sources, including purely form-based bottom-up information.
authors.affiliation: Department of Germanic Linguistics, University of Hannover, Hannover, Germany.
authors.forename: Netaya
authors.initials: N
authors.lastname: Lotze
authors.forename: Sarah
authors.initials: S
authors.lastname: Tune
authors.forename: Matthias
authors.initials: M
authors.lastname: Schlesewsky
authors.forename: Ina
authors.initials: I
authors.lastname: Bornkessel-Schlesewsky
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001931:Brain Mapping; D032882:Comprehension / Q000502:physiology*; D004569:Electroencephalography; D005071:Evoked Potentials / Q000502:physiology*; D005260:Female; D006801:Humans; D007600:Judgment / Q000502:physiology; D007807:Language Tests; D008297:Male; D010364:Pattern Recognition, Visual / Q000502:physiology*; D010775:Photic Stimulation; D011930:Reaction Time / Q000502:physiology; D012660:Semantics; D055815:Young Adult