Early development of lexical comprehension and production in an Italian sample: a longitudinal study.

Longitudinal studies conducted on small samples through direct observation of infants’ gesture and linguistic communication have underlined that the period between 10 and 18 months is a critical one for the emergence of lexical comprehension and gesture production and their relations with early lexical production (Bates, Benigni, Bretherton, Camaioni, Volterra, 1979; Capirci, Contaldo, Caselli, Volterra, 2005). Other studies conducted cross-sectionally on large samples through the use of the CDI long form administered to parents of 8- to 17-month-old infants have found similar results and have underlined that lexical comprehension is correlated with gesture production and precedes the development of lexical production which becomes quantitatively similar to gesture production around 16-17 months (Caselli, Casadio, 1995). Recently a short form of the CDI has been developed in order to quickly assess early language development; this form is also useful in longitudinal studies where repeated administrations of the long form would be impractical (Fenson, Pethick, Renda, Cox, Dale, Reznick, 2000). The aim of our study is to examine longitudinally (monthly between 10 and 17 months) through the Italian short form of the CDI (Caselli, Pasqualetti Stefanini, 2007) early development of lexical comprehension and production and gesture and their relations in an Italian sample of infants paying attention to individual profiles. Method. Participants. Seven monolingual Italian children (2 females, 5 males) were longitudinally examined (monthly from 10 to 17 months). Children at risk (e.g., preterms, twins) or with linguistic delays were excluded. Tool. The Italian short form of the CDI was monthly filled in by parents. The questionnaire is constituted by four parts: 1 A 100-word vocabulary checklist with separate columns for comprehension and production 2 18 questions to investigate non verbal communication (actions and gestures) 3 18 items to observe infant’s behavior (e.g., babbling, symbolic play) 4 Anamnestic information Results. Descriptive analyses run on part 1 and 2 of the CDI showed an increasing of lexical comprehension and gesture from 10 to 17 months, except in one child which had a minimum change in words comprehended. These results underline the importance to analyze lexical comprehension and gestures in this range of age, with attention to individual profiles. In relation to lexical production, the analyses revealed that children produced few words until 13 months, while afterwards a large variability was present with different individual trends in vocabulary acquisition. Correlations showed that gestures, lexical comprehension and lexical production in the first months (10- 13 months) were strongly correlated with the same abilities in the following months (i.e., gestures with gestures, comprehension with comprehension and production with production). In addition, a strong relation between lexical comprehension and gestures was found. By contrast, the correlations between lexical comprehension and production were spared because of the large variability found in lexical production. The results underline the importance to check through the short form of the CDI these abilities longitudinally in this developmental period in order to identify children with difficulties in linguistic comprehension, taking into account gesture production and monitoring the emergence of lexical production.