The cognitive processing of contrastive focus and its relationship with pitch accent
2017, 49 (9):
Information structure (IS) is a very important pragmatic concept in linguistics. It has been broadly studied in linguistics, psychology, neuroscience, etc. IS can be generally distinguished as focus/new information and background/given information. It is proper for focused/new information to receive accent. Recently, researchers have shown increasing interest in the neural mechanism of focus processing and its relationship with pitch accent. It was generally found that focus elicited a widely distributed positivity compared to background (non-focused) information in both visual and auditory domain, although these positivities varied in time course, amplitude and scalp distribution. As for its relationship with pitch accent, the results are complicated due to the variability in task (prosodic, semantic), language (German, Dutch, and Chinese, etc.), focus-marking device (context-question, pitch accent, it cleft structure, etc.), as well as information status (being new or given information). The present study aims to investigate the processing of contrastive focus and its interaction with pitch accent at different positions using ERPs. We used a highly constraining question as context, which posited two single nouns (NP1 and NP2) at different positions (in the medial and end of clause) in the answer sentence as contrastive focus (new information, narrow focus). Twenty (nine males) healthy undergraduates participated in the experiment. The participants were told to listen carefully to each dialogue, and completed a sentence comprehension task. The EEG was recorded from 64 scalp channels using electrodes mounted in an elastic cap. Focus and accent related ERPs were calculated for a 1500 ms epoch including a 200 ms pre-critical words baseline. It was found that focus evoked a larger positivity compared to non-focus at both positions. This was convinced by the statistical analysis result at both NP1 during 650-1300 ms, F(1, 19) = 8.29, p < 0.05, η2p = 0.29, and NP2 during 550-1050 ms, F(1, 19) = 14.45, p < 0.001, η2p = 0.38. Besides, accented words elicited a larger positivity than unaccented ones at both of NP1 (950-1150 ms), F(1, 19) = 7.39, p < 0.05, η2p = 0.22, and NP2(1050-1400ms), F(1, 19) = 8.04, p < 0.05, η2p = 0.30. Furthermore, missing accent on focus did not elicit any observable brain effect compared to accented focus at both positions in the lateral area, F(1, 19) < 1, ps > 0.05. At the end of the clause, however, accent on background information elicited a larger negativity (200-350 ms) compared to consistently unaccented background, F(1, 19) = 10.84, p < 0.01, η2p = 0.38, while there was no significant difference between accented and unaccented focus, F(1, 19) < 1, p > 0.05. Overall, the positive effect elicited by focus at both positions may reflect that listeners consume more cognitive resource to integrate focus to discourse compared to non-focus. Besides, accented words elicited a larger positivity than unaccented ones at both positions, indicating that prosodic prominence attracted more attention than unaccented information. Finally, accent on non-focus evoked a larger negativity compared to unaccented non-focus at the end of the clause. This result may reflect that listeners were sensitive to the information structure induced by pitch accent and the processing were influenced by the position of focus. In sum, the current results suggest that listeners make on-line use of both focus and pitch accent in various ways at different positions to build coherent representations of dialogues.
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