Ostensive definition in vocabulary teaching

Ostensive definitions of words are ambiguous as to their referent. In a study of 40 mother—infant dyads engaged in looking at picture-books, it was found that 95 % of ostensive definitions referred to the whole object depicted, rather than to its parts, attributes or actions. On the rare occasions when mothers named parts of objects, they avoided misunderstanding of the level of reference either by naming the part immediately after naming the whole, or by including a reference to the whole in the definition of the part. What's that? questions are not used to request labelling of the part.