The acquisition of personal pronouns and proper names by an identical twin pair.

Twins have been reported to suffer both identity confusion and language delay as a result of their twinship. Evidence for such difficulties was sought by studying the acquisition of personal pronouns and naming conventions in one pair of identical twin boys from age 2:1 to 2:10. The twins' acquisition of personal pronouns was in accordance with nontwin norms. Their apparent delay in conventional proper name use was attributed to the invention of the word Gaga as a referent for self and other twin. As proper name use emerged, Gaga use declined, whereas personal pronouns remained relatively independent. We concluded that the twins gave no evidence of either an identity confusion or a genuine delay in naming. Rather, the difference in the acquisition of names between these twins and nontwins was the additional step of first naming the twinship before naming each twin, which nontwins would not have a reason to do.