We investigate the role of phonological phrase boundary cues on syntactic parsing by Brazilian Portuguese (henceforth, BP) native adults. It is assumed that speech is organized in a hierarchy of prosodic constituents that may relate to constituents of other components of grammar (Nespor e Vogel, 1986). Although this is not necessarily a one-to-one relationship, a mapping is possible between constituents of each component, such as between phonological phrases and certain syntactic unit. The production of reliable prosodic cues in spontaneous speech is controversial. For instance, Snedeker e Trueswell (2003) propose that only expert speakers produce disambiguating prosodic cues; for Kraljic e Brennan (2005), even naïve speakers produce prosodic cues that are helpful for listeners. Millotte et al. (2007) found that French native speakers produced reliable prosodic cues (phrase-final lengthening and pitch rise) when they read pairs of ambiguous sentences that differed in their prosodic structures. The authors also found that native listeners were able to use these cues to assign the ambiguous words to their correct lexical categories. Then, -boundary cues may help native listeners to correctly analyze ambiguous sentences. Motivated by the French experiment results, we proposed two experiments in order to test the influence of prosody on syntactic analysis by BP adults. In the first experiment, a sentence-reading task, participants produced different prosodic patterns for ambiguous words (verb or adjective) in different syntactic structures. Duration, pitch and energy values of the segments around the -boundaries were measured and revealed that (i) -boundaries were marked by acoustical reliable cues; and (ii) the lexical categories N, V and ADJ have different behaviors in the prosodic structure.
Figure A: Example of the Noun + ambiguous word - Adj [garota MUDA]  (on the left) and V [garota]  [MUDA…] (on the right).
In the second experiment, listeners were asked to complete the auditory ambiguous sentences that were just cut after the target words (Eu acho que a menina LIMPA… . I think the clean girl…/the girl cleans…). Participants gave more verb responses in the Verb condition and more adjective responses in the Adjective condition. These results suggest that BP adults are able to use phonological phrase boundary cues to decide if an ambiguous word is a verb or an adjective and, then, to constrain syntactic analysis. We discuss the implication of these results for models of online syntactic analysis and language acquisition.
Figure B: Experiment 2- Mean number of adjective and verb responses given to adjective and verb sentences (out of 4 possible responses for each sentence type)

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