Tested the hypothesis that explicit identification of message ambiguity as a reason for failure in referential communication could help young children to gain understanding about the need for unique reference in communicative acts, in both experimental and natural settings. In the experiment each of 47 children aged 5-2 to 6-5 selected and then described clothes for a doll so that the experimenter could choose matching items. Ambiguous instructions from the children were consistently responded to with one of three reactions by the experimenter: (1) she guessed an item, (2) she asked ‘Which one?’ waited and chose or (3) she made explicit why she could not make a unique choice on the basis of the child's message. Both before and after this manipulation children were assessed for their understanding that messages can be ambiguous and can cause communication failure. Children accorded the third treatment improved most both in understanding and in reducing the ambiguity of their messages.
A similar assessment of understanding was made of 36 6-year-old children of whom recordings of interaction in the home had been made over several previous years. Children whose mothers had made explicit their lack of understanding of their child's utterances were more advanced than those whose mothers had not.