Gestural development and its relation to language acquisition in very preterm children

Abstract

This longitudinal study examined the development of communicative gesture in 16 preterm children and two groups of full term children at 12, 18 and 24 months of age. Children's spontaneous communicative gestures were analyzed during mother–child observation sessions. Preterm children's motor, mental and linguistic development were also measured. The development of gestural communication did not significantly differ between the groups except for the use of gesture-plus-word combinations at 18 and 24 months, when full term children produced significantly more combinations than preterm children. For preterm children, the production of pointing at 12 months was positively associated with lexical skills at 24 months as was the use of gestures-plus-word utterances at 18 months with morphosyntactic skills at 24 months. Our analyses also revealed a subgroup of preterm children characterized by a low birth-weight and mental scores who demonstrated an enduring increase in communicative gesture production over time. This profile could be associated with later delays in language acquisition.

Introduction

Preterm birth represents an alarming risk for the health status and developmental outcomes of infants. Preterm infants are affected by a sudden interruption of central nervous system maturation that can negatively shape later physical and mental development. Moreover, the Neonatal Intensive Care Unit (NICU) represents an extremely intrusive and artificial early developmental environment that may constitute a major challenge for vulnerable preterm infants (Bremmer et al., 2003, Thomas and Uran, 2007). Given a recent increase in the amount of preterm births, these concerns led to a renewed interest in investigating the development of children born prematurely (Alexander and Slay, 2002, Langhoff-Roos et al., 2006).

Numerous studies addressing preterm children's communicative and language development have indicated the presence of delays and deficits in several aspects of the linguistic domain. Starting with preverbal development, preterm infants exhibit delays in the production of their first vocalizations (Brown et al., 1986, Salerni et al., 2007) and in the later development of phonological skills, such as the emergence of canonical babbling (Nardelli de Oliveira et al., 2003, Rvachew et al., 2005). Moreover, research on preterm infants’ prelinguistic productions between the first and the second year of life reveals the presence of limited and less complex phonological inventories than those exhibited by full term children (Bortolini et al., 1996, D’Odorico et al., 2010, Jensen et al., 1988). With regard to later language development, recent research has shown that at two years of age preterm children exhibit delays in early lexical and grammatical acquisition (Foster-Cohen et al., 2007, Kern and Gayraud, 2007). In particular, Kern and Gayraud (2007) examined vocabulary size and composition of 323 preterm and 166 full term children at 24 months by administrating the MacArthur-Bates Communicative Inventories to parents (Fenson et al., 1993). Their results showed that extremely and very preterm children exhibit a smaller vocabulary size, a smaller MaxLU (maximum length of utterance) and fewer nouns and verbs than their full term peers. Similar results have been found by Foster-Cohen et al. (2007). In their study, significant linear associations were found between gestational age and language outcomes, with shorter gestational ages related to a smaller vocabulary size, limited morphological skills and delays in the use of irregular and over-regularized nominal and verbal forms. In light of these findings, it is extremely important to further explore language development in preterm children from a prevention perspective, taking into account factors that could predict and preemptively identify communicative delays and deficits in this atypical population of children.

Continuity between gestural prelinguistic communication and later language acquisition has been largely discussed in terms of typical development (Tomasello, 2008), addressing the concurrent and predictive relations between the emergence of specific communicative gestures and the acquisition of particular lexical and morphosyntactic skills. Deictic gestures (showing, pointing, giving) are the first communicative gestural behaviors to emerge in children's repertories at the end of their first year. With deictic gestures, children begin to exhibit the intention to share with their social partners their attention focus or interest on an object or event. Several studies have shown that the onset of deictic gestures is associated with the emergence of children's first verbal comprehension skills at around the same age. With their Bridge Hypothesis, Fenson et al. (1994) argue that deictic gestural communication represents a connection in the transition from verbal comprehension to verbal production. Moreover, the onset of pointing production in infant communication has been a valid predictor of children's later vocabulary size, in terms of both production and comprehension (Bates et al., 1979, Desrochers et al., 1995, Harris et al., 1995). From early in their second year of life, children exhibit a new kind of gesture that has been defined as referential or representational. These new gestures are symbolic in nature and are used by children to convey the meaning of an object or event to a social partner. The production of referential gestures is positively related to the emergence of naming skills, though this association has been only found in 12–18 months old, typically developing children (Bates & Dick, 2002). Several studies have demonstrated that referential gestures tend to disappear from children's communicative repertories at the end of their second year, being substituted by a more mature lexical production. This transition from gestural to verbal labeling seems to be delayed in late bloomers children, who tend to compensate for their immature verbal skills with a prolonged use of referential gestures (Thal & Tobias, 1992). However, even after typically developing children begin to talk, they continue to produce communicative gestures in combination with words. Through these combinations of gestures and words, children get used to conveying more than one meaning with a single utterance. Therefore, the production of gesture-plus-word combinations seems to pave the way for the onset of word combinations. In this regard, investigations conducted on typically developing children have found that the onset of supplementary gesture-word combinations predicts the emergence of later word combinations (Bates and Dick, 2002, Capirci et al., 1996, Iverson and Goldin-Meadow, 2005).

Although there have been several studies on the development of gestural communication among atypically developing children such as late talkers (Fasolo and D’Odorico, 2002, Thal and Tobias, 1992), children with Down syndrome (Iverson et al., 2003, Zampini and D’Odorico, 2009) and children with Williams syndrome (Laing et al., 2002), investigations examining this topic in preterm children are still rare. In a recent study by Cattani et al. (2009), the communicative and linguistic development of 12 preterm children was examined longitudinally from 12 to 18 months of chronological and corrected age with the MacArthur-Bates Communicative Development Inventory, Italian version (Primo Vocabolario del Bambino-PVB; Caselli & Casadio, 1995). When their corrected age was considered, preterm children's scores on the action/gesture scale fell within the normal range. Using chronological age, however, preterm children's action/gesture score fell between the 27th and 33rd percentiles. These results have been partially corroborated in a recent study by Fasolo, D’Odorico, Costantini, and Cassibba (2010), which investigated the preverbal and verbal development of 18 preterm children from 14 to 36 months of corrected age. In the first session, when children were 14 months old, their spontaneous gestural production was explored. However, significant differences in the amount of gestures produced by the preterm and full term children did not emerge.

Given these observations and the lack of consistent longitudinal studies on this topic, further investigations are required to shed light on the development of communicative gestures in preterm children. Therefore, the current study investigated the development of communicative gestures in a sample of preterm children at 12, 18 and 24 months of corrected age by analyzing their spontaneous gesture production during semi-structured mother–child interactions. In particular, the present longitudinal study had three aims. The first goal was to verify whether the preterm birth condition influences the emergence and production of communicative gestures during the second year of life. To explore this possibility, the amount and variety of spontaneous gestures produced by preterm children were compared to those observed in full term peers. Secondly, our purpose was to examine the developmental changes of gestural communication, taking into account the presence of different developmental profiles. The final purpose of this study was to investigate concurrent and predictive relations of the emergence and characteristics of gestural communication with children's linguistic, mental and motor skills. This last aim was pursued to determine whether eventual delays in gestural communication development are associated with more general cognitive or motor issues. Moreover, focusing on an association between the development of communicative gestures and language acquisition can help verify whether the emergence of particular gestures could serve as an early predictor of preterm children's later language development, as widely documented in studies on typical and atypical development.