Literacy Acquisition in a German Dialect: A Behavioral and EEG Study in Swiss-German and Standard German Speaking Children

We review the discovery, characterization, and evolving use of the N400, an event-related brain potential response linked to meaning processing. We describe the elicitation of N400s by an impressive range of stimulus types--including written, spoken, and signed words or pseudowords; drawings, photos, and videos of faces, objects, and actions; sounds; and mathematical symbols--and outline the sensitivity of N400 amplitude (as its latency is remarkably constant) to linguistic and nonlinguistic manipulations. We emphasize the effectiveness of the N400 as a dependent variable for examining almost every aspect of language processing and highlight its expanding use to probe semantic memory and to determine how the neurocognitive system dynamically and flexibly uses bottom-up and top-down information to make sense of the world. We conclude with different theories of the N400's functional significance and offer an N400-inspired reconceptualization of how meaning processing might unfold.

Event-related brain potentials (ERPs) were recorded from young adult subjects as they silently read 160 different seven-word sentences, presented one work at a time. The sentences either ended normally or were completed by unexpected words that were either semantically inappropriate, physically deviant or both. These two types of deviations were associated with distinctly different ERP components - a late negative wave (N400) for semantic deviations and a late positive complex for physical deviations. A deviation along either one or these dimensions (semantic or physical) did not appear to alter the ERP effect of a concurrent deviation along the other. In addition, it was found that the ERPs elicited by the words during the reading condition were characterized by a left-greater-than-right asymmetry in a slow, positive component. This asymmetrical scalp distribution was most pronounced for right-handed subjects having not left-handers in their immediate family.