Abstract

Twenty subjects for each of the following age levels: 5;4 - 7;11 - 9;10 - 13;4 - 20;4 were submitted to a definition task using the italian version of the Stanford-Bi-net (L-M Form) Vocabulary Scale. The aim of the study was to identify the main trends in the development of definitional skills, assuming that both appropriate contents and correct and complete linguistic forms do contribute to make good definitions. These two kinds of components, however, are analyzed separately, and the acquisition of more and more complex morpho-syntactic structure is considered the basic process which characterizes the shift from natural to metalinguistic definitions. While the former simply describe objects, events, properties, etc. referred to by the definiendum, the latter establish an equivalence/substitution relationship between the definiendum and the definiens. Five levels of definitional skills were identified, from Level I (Non Verbal or No Responses) to Level V. At this higher level, complex periphrases express the correct meanings of the stimulus word in terms of both superordinate or other abstract terms (genus proximum) and discriminating predicates (differentia specifica). As for the intermediate levels, Level II is characterized by the use of single words as a response to the stimulus word; Level III, by the production of incomplete syntactic structures; Level IV, is characterized by syntactically complete, selfsufficient utterances and by the systematic use of the copula but not yet by discriminating contents. Data show a decline of Level I, II and III responses, an increase of Level IV and of Level V responses, as a function of age.