The Speech Focus Position Effect on Jaw–Finger Coordination in a Pointing Task

PURPOSE: This article investigates jaw-finger coordination in a task involving pointing to a target while naming it with a CVCV (e.g., /papa/) versus CVCV (e.g., /papa/) word. According to the authors' working hypothesis, the pointing apex (gesture extremum) would be synchronized with the apex of the jaw-opening gesture corresponding to the stressed syllable. METHOD: Jaw and finger motions were recorded using Optotrak (Northern Digital, Waterloo, Ontario, Canada). The effects of stress position on jaw-finger coordination were tested across different target positions (near vs. far) and different consonants in the target word (/t/ vs. /p/). Twenty native Portuguese Brazilian speakers participated in the experiment (all conditions). RESULTS: Jaw response starts earlier, and finger-target alignment period is longer for CVCV words than for CVCV ones. The apex of the jaw-opening gesture for the stressed syllable appears synchronized with the onset of the finger-target alignment period (corresponding to the pointing apex) for CVCV words and with the offset of that period for CVCV words. CONCLUSIONS: For both stress conditions, the stressed syllable occurs within the finger-target alignment period because of tight finger-jaw coordination. This result is interpreted as evidence for an anchoring of the speech deictic site (part of speech that shows) in the pointing gesture.