Eyebrow raising in dialogue: discourse structure, utterance function, and pitch accents

Abstract

Some studies have suggested a relationship between eyebrow raising and different aspects of the verbal message, but our knowledge about this link is still very limited. If we could establish and characterise a relation between eyebrow raises and the linguistic signal we could better understand human multimodal communication behaviour. We could also improve the credibility and efficiency of computer animated conversational agents in multimodal communication systems.This thesis investigated eyebrow raising in a corpus of task-oriented English dialogues. Applying a standard dialogue coding scheme (Conversational Game Analysis, Carletta et al., 1997), eyebrow raises were studied in connection with discourse structure and utterance function. Supporting the prediction, more frequent and longer eyebrow raising occurred in the initial utterance of highlevel discourse segments than anywhere else in the dialogue (where 'high-level discourse segment' = transaction, and 'utterance' = move, following Carletta et al.). Additionally, eyebrow raises were more frequent in instructions than in requests for or acknowledgements of information. Instructions also had longer eyebrow raising than any other type of utterance. Contrary to the prediction, the start of a lower-level discourse segment (conversational game) did not have more eyebrow raising than any other position in the dialogue, and queries did not have more eyebrow raising than any other type of utterance.Eyebrow raises were also studied in relation to intonational events, namely pitch accents. Results showed evidence of alignment between the brow raise start and the start of a pitch accent. Most pitch accents were not associated with brow raising, but when brow raises occurred they tended to immediately precede a pitch accent on the speech signal. To investigate what could explain the alignment between the two events, pitch accents aligned with eyebrow raises were compared to all other pitch accents in terms of: phonological characteristics (primary vs. secondary pitch accents, and downstep-initial vs. non-initial pitch accents), information structure (given vs. new information in referring expressions, and the last quarter vs. earlier parts of the utterance length) and type of utterance in which they occurred (instruction vs. non-instruction). Those comparisons suggested that brow raises may be aligned more frequently with pitch accents in downstepinitial position and in instructions. No differences were found in terms of information structure or between primary/secondary accents.The results provide evidence of a link between eyebrow raising and spoken language. Eyebrow raises may signal the start of linguistic units such as discourse segments and some prosodic phenomena, they may be related to utterance function, and they are aligned with pitch accents. Possible linguistic functions are proposed, such as structuring and emphasising information in the verbal message.