The role of syntactic obligatoriness in the production of intonational boundaries

Researchers have hypothesized that words that are highly related semantically are more likely to occur within the same intonational phrase (F. zzaq;, 1988; E. O. Selkirk, 1984). D. Watson and E. Gibson (2004) proposed that semantic closeness can be captured by using the argument/adjunct distinction, such that intonational boundaries are more likely to occur before adjuncts than before arguments. In the current experiment, the authors compared two aspects of argumenthood: semantic relatedness and obligatoriness. In a production study, speakers were more likely to place an intonational phrase boundary between a word and a dependent if the dependent was optional (e.g., after "investigation" in "The reporter's investigation [of the crash] unnerved the officials") than if the dependent was obligatory (e.g., after "investigated" in "The reporter investigated [the crash], and this unnerved the officials"). These data suggest that obligatoriness is a better predictor of intonational boundary placement than semantic closeness.