Gradient prosodic boundary strength in syntactic disambiguation
Unlike syntactic structure, prosodic structure is typically thought of as non-recursive, with categorical boundaries delineating constituents within a rudimentary hierarchy. However, several experimental studies have demonstrated that prosodic boundaries are not produced categorically, and listeners are sensitive to these gradient variations in production, therefore suggesting that prosodic structure is more complex than normally assumed. While intriguing, it remains unclear whether such variability in boundary production is linguistically meaningful. Here, we explicitly test whether variability within a single class of prosodic boundary can be used to disambiguate sentences containing coordinative structures having multiple possible meanings. Interestingly, a majority of participants reliably employed gradient differences in pause duration to differentiate these ambiguous stimuli, demonstrating conclusively that listeners are not only able to perceive non-categorical variation in prosodic boundary strength, but that this variation can be linguistically meaningful. These results therefore indicate that prosodic structure may be less rigid than previously thought.