Pragmatic inferences modulate N400 during sentence comprehension: evidence from picture-sentence verification.

The present study examines the online realization of pragmatic meaning using event-related potentials (ERPs). Participants read sentences including the English quantifier some, which has both a semantic meaning (at least one) and a pragmatic meaning (not all). Unlike previous ERP studies of this phenomenon, sentences in the current study were evaluated not in terms of their truth with respect to the real world, but in terms of their consistency with a picture presented before the sentence. Sentences (such as "The boy cut some of the steaks in this story") were constructed such that either (1) both the semantic and pragmatic interpretations were true with respect to the preceding picture (when the boy in fact cut some but not all of the steaks); (2) neither interpretation was true (when the boy in fact cut none of the steaks); or (3) the semantic interpretation was true but the pragmatic interpretation false (when the boy in fact cut all of the steaks). ERPs at the object word, which determined whether the sentence was consistent with the story, showed the largest N400 effect for objects that made the sentence false, whereas they showed an intermediate effect for objects that made the sentence false under the pragmatic interpretation but true under the semantic interpretation. The results suggest that this pragmatic aspect of meaning is computed online and integrated into the sentence model rapidly enough to influence comprehension of later words.