Semantic detail in the developing verb lexicon: An extension of Naigles and Kako (1993).

Verbs are often uttered before the events they describe. By 2 years of age, toddlers can learn from such an encounter. Hearing a novel verb in transitive sentences (e.g. The boy lorped the cat), even with no visual referent present, they later map it to a causative meaning (e.g. feed) (e.g. Yuan & Fisher, ). How much semantic detail does their verb representation include on this first, underinformative, encounter? Is the representation sparse, including only information for which they have evidence, or do toddlers make more specific guesses about the verb's meaning? In two experiments (N = 76, mean age 27 months), we address this using an event type studied by Naigles and Kako (); they found that when toddlers hear a novel transitive verb while simultaneously viewing a non-causative referent-a contact event such as patting-they map the verb to the contact event. In Experiment 1 we replicated this basic result. Further, toddlers' representations persisted over a 5-minute delay, manifesting again during a retest. In Experiment 2, toddlers heard the verbs while watching two actors converse instead of while seeing contact events. At test, they showed no evidence of mapping the verbs to contact events, either initially or after a 5-minute delay, despite that in prior work they mapped verbs to causative events under identical circumstances. We infer that on hearing a novel verb in a transitive frame, absent a relevant visual scene, toddlers posit a more specific representation than the evidence requires-one that incorporates causative semantics. A video abstract of this article can be viewed at: https://youtu.be/aRCqSTbr6Bw.