Poster C73, Sunday, March 26, 5:00 – 7:00 pm, Pacific Concourse
A brain index of semantic prediction
Luigi Grisoni1, Natalie McCormick Miller1,2, Friedemann Pulvermüller1,2; 1Freie Universität Berlin, Brain Language Laboratory, Department of Philosophy and Humanities, 14195 Berlin, Germany, 2Berlin School of Mind and Brain, Humboldt Universität zu Berlin, 10099 Berlin, Germany
Most neuroscientists agree on the eminent importance of predictive mechanisms for understanding basic as well as higher brain functions. In spite of a large amount of electrophysiological (EEG) studies on preactivation and prediction in language understanding (Kutas & Federmeier, 2011), a direct EEG signature of semantic predictions in language understanding is still missing. Testing adult human participants, we show that, already before the presentation of a critical word, context-induced semantic predictions are reflected by an event-related potential (ERP), which we call the Semantic Readiness Potential (SRP). The SRP precedes critical words both in affirmative and negative sentence contexts with specific expected continuation, but not in unpredictable negated contexts. Specific semantic predictions are indexed by SRP sources within the motor system – in dorsolateral hand motor areas for expected hand-related words (e.g. “write”), but in ventral motor cortex for face-related words (“talk”). Compared to affirmative sentences, predictable negated ones led to medial prefrontal and more widespread motor source activation, consistent with predictive semantic computation of alternatives to the negated expected concept. Processing of semantic alternatives in negated sentences is further supported by N400 responses, which showed the typical enhancement to incongruent sentence endings only in predictable-affirmative contexts, but not in predictable-negated ones. These brain dynamics reveal the interplay between predictive and resolution (match vs. error) processing in semantic sentence understanding.
Topic Area: LANGUAGE: Semantic