Look-ahead planning of lexical heads in adjunct-head structures

This study investigates whether the scope of advance lexical planning is constrained by a head-adjunct dependency between words in a sentence. Participants produced Korean sentences beginning with a complex subject noun phrase consisting of a relative clause followed by a head phrase. The subject noun phrase had three nouns and were manipulated for whether the second noun was semantically related or unrelated to the first noun and whether it occurred inside the relative clause (two-noun modifier structures) or the head phrase (one-noun modifier structures). Speech onset latencies were modulated by both semantic relatedness and relative clause length. However, the two factors did not interact with each other. The results indicate that a head noun was planned in advance before their adjunct could be articulated even when it occurred outside a sentence-initial phrase. The data suggest that head-adjunct dependencies may necessitate advance access to major structural components and lead to a broad scope of lexical planning.