Effects of prosody and position on the timing of deictic gestures.

Purpose: In this study, the authors investigated the hypothesis that the perceived tight temporal synchrony of speech and gesture is evidence of an integrated spoken language and manual gesture communication system. It was hypothesized that experimental manipulations of the spoken response would affect the timing of deictic gestures.

Method: The authors manipulated syllable position and contrastive stress in compound words in multiword utterances by using a repeated-measures design to investigate the degree of synchronization of speech and pointing gestures produced by 15 American English speakers. Acoustic measures were compared with the gesture movement recorded via capacitance.

Results: Although most participants began a gesture before the target word, the temporal parameters of the gesture changed as a function of syllable position and prosody. Syllables with contrastive stress in the 2nd position of compound words were the longest in duration and also most consistently affected the timing of gestures, as measured by several dependent measures.

Conclusion: Increasing the stress of a syllable significantly affected the timing of a corresponding gesture, notably for syllables in the 2nd position of words that would not typically be stressed. The findings highlight the need to consider the interaction of gestures and spoken language production from a motor-based perspective of coordination.