ABSTRACT
15-month-olds behave as if they comprehend filler-gap dependencies such as wh-questions and relative clauses. On one hypothesis, this success does not reflect adult-like representations but rather a “gap-driven” interpretation heuristic based on verb knowledge. Infants who know that feed is transitive may notice that a predicted direct object is missing in Which monkey did the frog feed __? and then search the display for the animal that got fed. This gap-driven account predicts that 15-month-olds will perform accurately only if they know enough verbs to deploy this interpretation heuristic; therefore, performance should depend on vocabulary. We test this prediction in a preferential looking task and find corroborating evidence: Only 15-month-olds with higher vocabulary behave as if they comprehend wh-questions and relative clauses. This result reproduces the previous finding that 15-month-olds can identify the right answer for wh-questions and relative clauses under certain experimental contexts, and is moreover consistent with the gap-driven heuristic account for this behavior.
Disclosure statement
No potential conflict of interest was reported by the authors.
Notes
1 On many accounts, wh-phrases in these languages still take scope in a higher clausal position by undergoing covert displacement that happens to be inaudible (Aoun, Hornstein & Sportiche Citation1981; Huang Citation1982). Some have also argued for nonmovement accounts of wh-in-situ, such as binding by a covert operator (Reinhart Citation1998), or for different wh-in-situ representations across different languages (Cole & Hermon Citation1994). See Cheng (Citation2003) for an overview.
2 Note that the goal of this computational model was not to identify closed-class categories like wh-words but rather to use closed-class items to help identify lexical categories like nouns and verbs.
3 This particular analysis was chosen to be as similar as possible to the analysis conducted by Gagliardi, Mease & Lidz (Citation2016), who used a very similar design. At the suggestion of an anonymous reviewer, we also examined the interaction by sentence type in each window separately. A 2 × 2 between-subjects ANOVA (mean looks to money agent ~ gap site * sentence type) conducted for each test window also did not find any significant main effects or interactions.