Toddlers' word learning through overhearing: Others' attention matters.

In laboratory settings children are able to learn new words from overheard interactions, yet in naturalistic contexts this is often not the case. We investigated the degree to which joint attention within the overheard interaction facilitates overheard learning. In the study, 20 2-year-olds were tested on novel words they had been exposed to in two different overhearing contexts: one in which both interlocutors were attending to the interaction and one in which one interlocutor was not attending. Participants learned the new words only in the former condition, indicating that they did not learn when joint attention was absent. This finding demonstrates that not all overheard interactions are equally good for word learning; attentive interlocutors are crucial when learning words through overhearing.