Is the coupled control of hand and mouth postures precursor of reciprocal relations between gestures and words?

We tested whether a system coupling hand postures related to gestures to the control of internal mouth articulators during production of vowels exists and it can be precursor of a system relating hand/arm gestures to words. Participants produced unimanual and bimanual representational gestures expressing the meaning of LARGE or SMALL. Once the gesture was produced, in experiment 1 they pronounced the vowels "A" or "I", in experiment 2 the word "GRÀNDE" (large) or "PÌCCOLO" (small), and in experiment 3 the pseudo-words "SCRÀNTA" or "SBÌCCARA". Mouth, hand kinematics and voice spectra were recorded and analyzed. Unimanual gestures affected voice spectra of the two vowels pronounced alone (experiment 1). Bimanual and both unimanual and bimanual gestures affected voice spectra of /a/ and /i/ included in the words (experiment 2) and pseudo-words (experiment 3), respectively. The results support the hypothesis that a system coupling hand gestures to vowel production exists. Moreover, they suggest the existence of a more general system relating gestures to words.