There is a wealth of theoretical support and empirical evidence suggesting that aspects of infant communication, particularly those emerging in the second half of the first year, play an important role in shaping language learning trajectories. For instance, it has been argued by theorists such as Bruner1 and Tomasello2 that the attainment of the capacity to share attention with others at approximately 8–10 months is the greatest milestone en route to language learning. The crux of this argument is that the ability to share attention with others sets the stage for the child’s first experiences with shared meaning, crucial for development of language abilities, which requires common understanding of words for representing objects and concepts. This conjecture about the significance of this early communicative capacity has been robustly supported, with ample empirical evidence demonstrating that individual differences in joint attention behaviors during late infancy are associated with toddler and preschool language abilities 3.
There is also evidence suggesting that other aspects of communication, such as eye gaze, expression of emotion and attention getting, emerging even earlier in infancy, may also be critical for shaping trajectories of language development. Infant gaze-following is theoretically important because of its direct significance for word learning4, and it has been empirically shown as early as 6 months to be associated with later receptive and expressive language skills5,6. Research has also demonstrated that early aspects of infant communication such as eye gaze, emotion expression, and making bids for the attention of others strongly predict other communicative capacities emerging later in infancy, such as joint attention, which in turn set the stage for language development4. Taken together, the literature suggests that individual differences in infant communication are not only evident and detectable in early infancy, prior to the emergence of the capacity to share attention, but are also meaningful for further language development.
Given the significance of early forms of infant communication for later language learning, it is important to understand the ways in which they might be impacted by early differences in the social environment. A review of the literature on early childhood development leaves little doubt that cognitive stimulation in the context of parents’ interactions with their young children is critical7. Research on the language development of toddlers and preschoolers has established that stimulating children cognitively, through such reciprocal interactions such as reading, teaching, playing with toys, and other interactions involving verbal responsivity on the part of the parent, is associated with enhancements in children’s language development. Specifically, it has been consistently demonstrated that parents who use richer language input, who scaffold children’s vocalizations more in the context of play, and who read aloud more frequently to their children, have toddlers and preschool-aged children with more advanced language skills8.
While the evidence documenting the effect of cognitively stimulating interactions on late infant communication and todder/preschool language development is abundant, there has been limited study of whether and how variations in these interactions in early infancy are associated with individual differences in very early communication abilities such as eye gaze, emotion expression and making bids for the attention of others. The limited study of impacts in these domains is likely due to a host of factors, including that pre-verbal communication is less readily measurable than later language ability. Also, due to theoretical stipulations put forth by Piaget and others that young infants are in the sensorimotor phase of cognitive development - that is, not yet capable of representational thought - the role of “cognitive stimulation” in these early months may be less likely to be considered. However, such interactions in the earliest months of life are likely to shape the way that infants engage and communicate with others, and therefore likely to facilitate interactions in late infancy and toddlerhood, critical for language learning. This question of the impact of parenting on early infant communication is therefore of general importance for our understanding of how early experiences spur development, but also has practical importance for how pediatricians and practitioners advise parents early in infancy.
Answering this question would have relevance for the broader population but would have particularly great implications for children in low-income families, for whom: (1) research on the significance of early communication in relation to later language development is lacking; (2) language development often lags behind that of middle-class peers; and (3) early cognitive stimulation in the home is likely to be even more crucial. There is a longstanding body of research indicating that cognitive stimulation and verbal input in the homes of low-income families are less frequent than in middle-income homes 8. Furthermore, this relative lack of such verbally-rich parent-child interactions in low-income homes is a clear contributor to disparities in language development, and school readiness more generally, experienced by children reared in such environments9. Interventions seeking to mitigate such poverty-related disparities, delivered both in the home (e.g., Parent Child Home Program10, Play and Learning Strategies11) and in health care settings (e.g., Reach Out and Read12, Healthy Steps13, Video Interaction Project14–16), have thus aimed to enhance parent-child interactions. If it were indeed the case that cognitive stimulation beginning in early infancy impacted later language through enhancements to infant preverbal communication, this would provide strong support for working to enhance cognitive stimulation beginning as early in infancy as possible.
Accordingly, the present study aims: (1) to determine whether cognitive stimulation in early infancy is associated with preverbal aspects of infant communication at 6 months and with toddler language development at 24 months for a low-income sample; (2) to determine whether preverbal aspects of infant communication predict later toddler language development for this low-income sample; (3) to determine the extent to which early impacts of cognitive stimulation on infant communication are important in setting the course for further language learning - that is, to determine whether early communication mediates the relationship between early cognitive stimulation and 24-month language development; and (4) to perform exploratory analyses of whether specific aspects of cognitive stimulation in the home in early infancy are associated with early and late language indicators.
We hypothesized that early cognitive stimulation (measured at 6 months) would be associated with enhanced early infant communication (also measured at 6 months) and with subsequent toddler language outcomes (measured at 24 months). We also hypothesized that early infant communication would directly predict 24 month language outcomes. Finally, we hypothesized that the relationship between early cognitive stimulation and toddler language would be explained in part, by early impacts on infant communicative behavior.