Abstract: This study examined early vocal production to assess whether it is possible to identify predictors of vocabulary development prior to the age point at which lexical delay is usually identified. Characteristics of babbling and first words in 12 Italian children with slow expressive development (late talkers; LT) were compared with those of 12 typically developing (TD) peers. Syllable structure and phonetic characteristics of babbling and first words produced by both groups of children at 20 months were analysed during mother-child play sessions. Results indicated that phonetic complexity and number of consonantal types were lower in the LT group. The two groups also differed in their use of sound classes and their syllable structure. Overall, it can be said that LTs development is similar to (but slower than) TDs, as opposed to having an atypical pattern of phonological development.
Abstract: The vocabulary development of 24 Italian children aged between 1;4 and 1;6 at the beginning of the study was longitudinally monitored on a monthly basis using the Italian version of the MacArthur Communicative Development Inventory drawn up by their mothers. This study analyzes data from children for whom two sampling stages were available; the first corresponding to a vocabulary size as close as possible to 200 words (mean 217, range 167-281), the second to a vocabulary size ranging from 400 to 650 words (mean 518, range 416-648). The children's vocabulary composition was analyzed by calculating, for each sampling stage, the percentage of common nouns, verbs and closed-class words. The increase in percentage points of the various lexical items between the first and second sampling stages was also analyzed. Data confirmed the predominance of nouns over verbs and closed-class words at both sampling stages, while verbs and closed-class words showed a higher percentage increase than nouns. The results provide evidence that children who reached the first sampling point at an earlier age had a higher percentage of nouns than children who reached the same stage at an older age. However, in the passage from the first to the second sampling point no relationship emerged between a style of acquisition based on the acquisition of nouns and an increase in the rate of vocabulary growth.
Abstract: BACKGROUND: Children who have reached the age of 2 years without having acquired a 50-word vocabulary and/or who use no word combinations are referred to in the literature as 'Late Talkers'. Research has not yet identified the factors that cause slow development of expressive language; in particular, relatively little research has been carried out on the characteristics of the maternal linguistic input received by Late Talkers. In fact, the majority of studies in this area have focused principally on the mothers' semantic, pragmatic and interactive verbal behaviour. AIMS: The objective was to verify whether the input addressed to a group of Late Talkers differs to that addressed to a group of typically developing peers. It was expected that there would be differences in the prosodic and structural/lexical properties of the input, which by creating a 'less than optimal environment' for language acquisition processes, could affect the children's rate of linguistic development. METHODS & PROCEDURES: The spontaneous maternal speech of nine Italian-speaking mothers of late-talking toddlers (LT) at 20 months of age was examined and compared with that of nine mothers of age-matched children with typical language development (Late Starters). Data were collected during video-recorded play sessions, which were transcribed and coded based on the structural-lexical and acoustical characteristics of the mothers' speech. Group differences were tested for the following variables: number of utterances per minute, mean number of words per utterance (MLUw), number of nouns per minute, number of different nouns per minute, common nouns as a percentage of overall words, type/token ratio for common nouns, one-word utterances as a percentage of the total number of utterances, one-word utterances formed by a common noun as a percentage of the total number of utterances, mean syllable duration, duration of the final syllable of the utterance, F0 maximum (the highest F0 in the utterance), F0 minimum (the lowest F0 in the utterance) and F0 range (by subtracting F0 min from F0 max). OUTCOMES & RESULTS: The mothers of LT produced common nouns and mark nouns by a pitch peak with a significantly lower frequency than the mothers of the children with typical language development. The mothers of LT also used flat pitch contours more often than the mothers of the typically developing peers. CONCLUSIONS: The study provides evidence that maternal input addressed to Late Talkers can contribute to slowing the process of language acquisition. Based on these findings, additional investigations that examine the contribution of maternal verbal behaviour to the development of language delay are warranted.
Abstract: In this study vocabulary development of a sample of 42 Italian children was evaluated through monthly administration of the Italian version of the CDI. Data collection started at 1;0-1;1 for 32 children and at 1;3-1;4 for the remaining subjects and continued until children's vocabulary reached 200 words. At fixed stages of vocabulary size (50, 100 and 200 words), individual differences in percentile scores and vocabulary composition were examined. Individual growth curves were analysed in order to verify the presence of a vocabulary spurt and the type of lexical items which contributed most to rapid acceleration in vocabulary growth. Stylistic differences in vocabulary composition were examined regarding the 'referential-expressive' distinction, controlling vocabulary size. Data have shown that general trends in vocabulary development are quite similar to those obtained for other languages using CDI adaptations. Moreover, all children in this sample eventually exhibited a vocabulary spurt, even if some can be defined as 'late spurters'. The type of lexical items which are learned during the spurt depend on both infant vocabulary size and referential score. About 28% of infants in this sample were defined 'referential' when their vocabulary size was about 50 words, but the stylistic differences disappeared at the 100- and 200-word stages. Composition of vocabulary did not differ in relation to precocity in reaching different stages of vocabulary development. The only exception was that infants who reached the 50-word stage first also had a vocabulary with a lower proportion of function words.
Abstract: This work reports longitudinal evaluation of the temporal relationships between gaze and vocal behavior addressed to interactive partners (mother or experimenter) in a free-play situation. Thirteen children were observed at the ages of 1;0 and 1;8 during laboratory sessions, and video recordings of free-play interactions with mother and a female experimenter were coded separately for children's vocal behavior (vocalizations and words) and gaze toward their interactive partners. The difference between the observed and expected co-occurrence of these two communicative behaviors was evaluated by transformation into z-scores. The most important findings are related to differences in the temporal relationship observed at age 1;0 between gaze and vocalizations and at age 1;8 between gaze and words. At the earlier age, the infants who exhibited greater coordination between gaze and vocal behavior than was expected by chance (z-score > +1.96) preferred to look at the interlocutor at the beginning of the vocal turn. Instead, when they were older and began to produce words, they frequently looked at the interlocutor at the end of the vocal turn. These results are interpreted as referring to characteristics of conversational competence in the prelinguistic and lingustic periods. Moreover, looking at the interlocutor at the beginning of the vocal turn at age 1;0 was found to be related to language production at age 1;8, highlighting a significant relationship between conversational competence during the prelinguistic period and language acquisition.
Abstract: This study investigates the production of vocalization in adult-infant-toy interactions from 0;4 to 0;11. The hypothesis is that vocalizations are selectively uttered in relationship to their production context. Five infants (two girls, three boys) were intensively studied. Non-segmental acoustic features of vocalizations in four communicative contexts were analysed in relation to the individual infants, in order to reveal individual differences. The data were submitted to discriminant function analysis. Results show that (a) different patterns of non-segmental features characterize sounds produced in different contexts; (b) both inter-subject differences and intra-subject consistency are observed; (c) 'selective production' disappears after 0;9. These results are discussed in relationship to sound-meaning development.
Abstract: Twenty men and 20 women with children under 3 years of age, and 20 men and 20 women without children were asked to select the most suitable utterance for a series of drawings representing different contexts of mother/father-infant interaction. Data were analyzed in three sections related to different hypotheses: In Phase 1, informational content and syntactic construction of sentences were selected in strict relationship with context by all speakers ("closeness to context" rule); in Phase 2, different speech acts were selected by different speakers within the same context (analysis of illocutionary force and canonicality); in Phase 3, the same contexts were linked to different interactional dimensions for the four groups, which formed different representations of the same interactional scene. Results are discussed in an attempt to integrate specific rules of adult-infant interaction and more general aspects of discourse production.
