Children use contrast, multiple familiarization scenes, and multiple object categories to learn verbs

Recent work exploring children's verb learning in the laboratory has generated some interesting contradictions. Some studies have found that children as old as 4 years old are unable to reliably map a novel verb to an action (e.g., Kersten & Smith, 2002; Imai, Haryu, & Okada, 2005), even though much younger children routinely acquire and produce verbs in a naturalistic setting. In contrast, Waxman, Lidz, Braun, and Lavin (under review) found that infants as young as 24 months could identify an action category across dynamic scenes and map a novel verb (but not a novel noun) to that action category. In the current research, I extend the work of Waxman et al. by independently manipulating three factors---multiple familiarization scenes, multiple object categories, and explicit contrast---in a forced choice verb-learning task with 3-year-olds. Children watched one or more familiarization scenes in which an actor performed a simple, durative action with a familiar object. Scenes were labeled with either a novel verb (e.g., "The man is larping a balloon!") or novel noun (e.g., "The man is waving a larp!"). A contrast phase showed the same actor perform a different action with a different object, labeled in the negative (e.g., "Uh, he's not larping that!"), which was followed by another familiarization scene. At test, children were shown two scenes simultaneously: one scene showed the actor performing a new action with the familiar object, and the other showed the actor performing the familiar action with a new object. Participants were asked to point to the scene representing the novel word. Children learned verbs best when all three sources of information---multiple familiarization scenes, multiple object categories, and contrast---were available. When only one was available, contrast appeared to be the most useful. The use of multiple object categories across scenes facilitated verb learning more than a single object category. Children deprived of all three sources of information did not learn verbs at all, but did learn nouns. Ways in which the information required for learning a verb may differ from that required for learning a noun are discussed.