Prespeech vocalizations and the emergence of speech: a study of 1005 Spanish children.

This study investigates 12 prespeech vocal behaviors which are taken to reflect children's phonological, communicative and early symbolic development. It explores their development (onset, duration and extinction) and their relation to early lexical development. A structured parental questionnaire on prespeech vocalizations was developed, validated and used for the evaluation of 1005 Spanish children's early vocal development (8-30 months). In parallel, the same children's productive vocabulary was assessed using the vocabulary section of the European-Spanish MacArthur-Bates Communicative Development Inventories. Results highlight a global inverted U-shaped developmental pattern which emerges from the asynchronous development of the vocal behaviors examined, relating both their emergence and extinction to advances in linguistic development. Moreover, the protracted coexistence of prespeech vocalizations with early speech and their significant correlations with vocabulary size reveal a gradual transition into language. Overall results reinforce and extend previous findings on the development of prespeech vocalizations and establish their relevance as early indexes of linguistic development. Finally, positive evidence on the use of an assisted parental report method for reliably evaluating these developments is provided. Results are discussed within theoretical frameworks that conceive language as the emergent product of complex developmental processes.