Structure and performance at prosodic boundaries: The effect of planning and syntactic structure on the kinematic properties of gestures

Prosodic boundaries typically occur at strong, rather than weak, syntactic boundaries. However, in addition to structural factors, performance factors (such as speech planning) also might affect the occurrence and properties of prosodic boundaries. For example, speakers needing more time for planning an upcoming chunk of speech might show an increase in pause duration at prosodic boundaries. The present study tests whether planning (of an upcoming chunk of speech) interacts with syntactic structure in the production of prosodic boundaries, focusing on the temporal properties of boundaries (final lengthening and pausing). Kinematic data were collected from seven American English speakers using electromagnetic articulography. Participants produced 224 sentences varying in the amount of planning (more or less planning) and location of planning (hierarchically high (strong) or hierarchically low (weak) syntactic boundary), and read sentences as control sentences. Preliminary results show that at both higher and lower syntactic boundaries, the effect of planning is such that lengthening occurs mainly at pauses and pause-surrounding gestures, but at lower syntactic boundaries (compared to higher boundaries), there is significantly more lengthening pre-pausally and pauses are qualitatively shorter. Thus, the planning strategies speakers employ depend on whether prosodic boundaries are motivated by syntactic structure or not.