WHEN PROSODY FAILS TO CUE SYNTACTIC STRUCTURE - 9-MONTH-OLDS SENSITIVITY TO PHONOLOGICAL VERSUS SYNTACTIC PHRASES

According to prosodic bootstrapping accounts of syntax acquisition, la nguage learners use the correlation between syntactic boundaries and p rosodic changes (e.g., pausing, vowel lengthening, large increases or decreases in fundamental frequency) to cue the presence and arrangemen t of syntactic constituents. However, recent linguistic accounts sugge st that prosody does not directly reflect syntactic structure but rath er is governed by independent prosodic units such as phonological phra ses. To examine the implications of this view for the prosodic bootstr apping hypothesis, infants in Experiment 1 were presented with sentenc es in which pauses were inserted either between the subject noun phras e (NP) and verb or after the verb. Half of the infants heard sentences with lexical NP subjects, in which prosodic structure is consistent w ith syntactic structure. The other half heard sentences with pronoun s ubjects, in which prosodic structure does not mirror syntactic structu re. In a preferential listening paradigm, infants in the lexical NP co ndition listened longer to materials containing pauses between the sub ject an verb, the main syntactic constituents. However, in the pronoun NP condition, infants showed no difference in listening times for the two pause locations. To determine if other sentence types containing pronoun subjects potentially provide information about the syntactic c onstituency of these elements, infants in Experiment 2 heard yes-no qu estions with pronoun subjects, in which the prosodic structure reflect s the constituency of the subject, Infants listened longer when pauses were inserted between the subject and verb than after the verb. Taken together, our results suggest that the prosodic information in an ind ividual sentence is not always sufficient to assign a syntactic struct ure. Rather, learners must engage in active inferential processes, usi ng cross-sentence comparisons and other types of information to arrive at the correct syntactic representation.