Less Is Not More: Neural Responses to Missing and Superfluous Accents in Context

■ Prosody, particularly accent, aids comprehension by drawing attention to important elements such as the information that answers a question. A study using ERP registration investigated how the brain deals with the interpretation of prosodic promi-nence. Sentences were embedded in short dialogues and con-tained accented elements that were congruous or incongruous with respect to a preceding question. In contrast to previous studies, no explicit prosodic judgment task was added. Robust effects of accentuation were evident in the form of an “accent positivity ” (200–500 msec) for accented elements irrespective of their congruity. Our results show that incongruously accented elements, that is, superfluous accents, activate a specific set of neural systems that is inactive in case of incongruously un-accented elements, that is, missing accents. Superfluous ac-cents triggered an early positivity around 100 msec poststimulus, followed by a right-lateralized negative effect (N400). This re-sponse suggests that redundant information is identified imme-diately and leads to the activation of a neural system that is associated with semantic processing (N400). No such effects were found when contextually expected accents were missing. In a later time window, both missing and superfluous accents trig-gered a late positivity on midline electrodes, presumably related to making sense of both kinds of mismatching stimuli. These results challenge previous findings of greater processing for miss-ing accents and suggest that the natural processing of prosody involves a set of distinct, temporally organized neural systems.