Marked pointing facilitates learning part names: A test of lexical constraint versus social pragmatic accounts of word learning.

The empirical study of word learning is driven by a theoretical debate between lexical constraint and social-pragmatic accounts; it has still not been determined which of these two best explains the evidence. We investigated whether the markedness of a pointing accompanying a verbal reference could help to learn a part name. Participants were 35 two-and-a-half-year-olds, 42 four-and-a-half-year-olds, and 38 undergraduate university students in Japan. The experimenter pointed to a novel part (embedded in a novel whole object) with either "marked" pointing, which was touching the part with a small circular motion, or with usual pointing. Touch accompanied by circular motion reliably elicited learning of part names in all age groups. Usual distal pointing without motion reliably elicited learning of whole object names. The pattern of findings rejects a whole-object constraint in early word learning and demonstrates that marked pointing can promote learning novel part names, supporting a social-pragmatic account.