Finger-jaw coordination during a deictic gesture with CVCV utterances: the effect of stress position

The present study investigates the hypothesis of a synchronization between the extremum (apex) of the pointing gesture and the apex of the jaw opening gesture for the stress vowel in 'CVCV vs CV'CV utterances in a deictic task (consisting in showing a target while naming it). The results show that for 'CVCV sequences (e.g. /pápa/) the pointing apex tends to be phased with the jaw apex for the first vowel. For CV'CV (e.g. /papá/), the pointing apex happens more or less at the mid-point between the jaw apices for the first and the second vowels. However, the onset of the hand return movement is synchronized with the jaw apex for the second vowel. The absolute timing of the forward movement of the finger does not depend on the stress condition, indicating that the differences in the relative timing between the jaw and the hand across conditions is a consequence of the speech gesture being adapted to the hand gesture. These results are discussed in relation to the results of Levelt et al. (1985) on speech-hand coordination in deictic expressions and regard to Abry et al.'s (2004) “Vocalize to Localize” framework.