Pointing to a target while naming it with /pata/ or /tapa/: the effect of consonants and stress position on jaw-finger coordination

This study investigates jaw-finger coordination in a task consisting in pointing to a target while naming it with a /pata/ or a /tapa/ utterance stressed either on the first ('CVCV) or on the second (CV'CV) syllable. Optotrack measurements of jaw and finger displacements show that for 'CVCV names, the moment at with the finger reaches the target alignment is synchronized with the maximum of the first jaw opening motion. For CV'CV names, the synchronization occurs between the moment at which the finger leaves the target-alignment position and the maximum of the jaw opening motion for the second vowel. This pattern of synchronization does not depend on the target position or on the consonants order. These results add some support to theories involving the coordination of orofacial and brachiomanual gestures in the development and phylogeny of human languages. They call for more investigations on the link between speech and brachiomanual gestures in face-to-face communication.