Object naming at multiple hierarchical levels: a comparison of preschoolers with and without word-finding deficits.

According to the storage hypothesis (Kail & Leonard, 1986), word-finding deficits in young children are not the direct results of deficient retrieval strategies; they are a manifestation of a general delay in language development that affects lexical storage. In the current study, we explored one aspect of lexical storage, the hierarchical organization of the semantic system, in 13 preschoolers with word-finding deficits (WF) and 13 preschoolers with normal language abilities (ND), ranging in age from 3;3 to 6;7. The children named a series of objects at multiple levels of the noun hierarchy in response to contrast questions (e.g. for rose they were asked, 'Is this an animal?' to elicit plant [superordinate]; 'Is this a tree?' to elicit flower [basic]; 'Is this a dandelion?' to elicit rose [subordinate]). Both groups readily named at multiple levels, providing evidence of hierarchical organization of the lexicon. However, there were several differences between WF and ND groups that suggested that WF children did not have enough stored information to discriminate between similar semantic neighbours. We conclude (1) that hierarchical organization of the semantic lexicon is a robust developmental phenomenon, apparent in both ND and WF preschoolers and (2) that the word-finding deficits of preschoolers appear to reflect insufficient depth and breadth of storage elaboration rather than deficits in hierarchical semantic organization.