In three studies, two-year-old children communicated to a parent which
of two out-of-reach objects contained a sticker. Across trials, the objects
were positioned in different configurations so that it was possible or
impossible for a child's pointing gesture to unambiguously specify one
object. In Study 1, the objects used were two boxes distinguished by a
different picture of a vehicle on the front, and children (n = 16; mean
age 2;8) were significantly more likely to name the box's picture on trials
where pointing alone could not unambiguously specify the box than on
trials where it could. In Studies 2 and 3, the stickers were hidden inside
different animal figures. Older two-year-olds (n = 16, mean age 2;9),
but not younger two-year-olds (n = 16, mean age 2;4), showed an ability
to recognize the referential (in)efficacy of their pointing gestures and to
adapt their communication accordingly.