Development of Self-Directed Speech and Planning among Preschoolers with Developmental Language Disorder - Many children with developmental language disorder (DLD) have higher-order cognitive deficits (i.e., executive function, problem solving, and planning) in addition to language impairment. Establishing the relation between language and cognition is important for our understanding of the nature of DLD and for developing approaches to improve cognition, which is crucial because higher-order cognitive skills predict later academic and career success. One possibility is that children with DLD have cognitive deficits because they are less successful relative to peers with typical language in utilizing self-directed speech (SDS; i.e., speech to oneself) to regulate their behaviors and thoughts. For example, children with DLD may be less likely to articulate steps while problem solving or verbally rehearse task rules. As such, language impairment may play a causal role in higher-order cognitive deficits in DLD via impaired SDS. Sociocultural models suggest that SDS begins as external regulatory speech from caregivers that children internalize to develop SDS. In this model, expressive language impairment would negatively affect a child’s ability to produce SDS, and receptive language impairments would reduce a child’s ability to understand caregivers’ external regulatory speech, which is central to SDS development. Few studies have examined SDS in DLD, but previous research indicates that children with DLD have immature SDS relative to typically developing peers. However, there is also promising evidence that SDS can be trained in children with DLD. Although children with DLD show immature SDS relative to typical peers, longitudinal research in this area is lacking, making it difficult to determine the developmental trajectory and discern why children with DLD lag behind typical peers. The first goal of this research is to document the longitudinal development of SDS in preschoolers with and without DLD in order to compare the groups in their SDS and planning abilities and to assess the relation between these variables over time. This goal will be achieved in Study 1 in which preschoolers with and without DLD will complete the Tower of Hanoi planning task four times over one year. The second goal is to elucidate the effects of SDS on planning performance in preschoolers with and without DLD. This will be addressed in Study 2 in which preschoolers with DLD and typical language will complete Tower of Hanoi four times in different experimental conditions that manipulate (i.e., prevent or encourage) SDS production. If task performance differs across the conditions, it suggests that planning is affected by increasing or decreasing SDS, supporting a causal relationship between SDS and cognitive performance. The third goal is to test the predictions of the sociocultural model with respect to the effects of expressive versus receptive-expressive language deficits on SDS. This goal will be addressed with data from children with DLD from Studies 1 and 2 by comparing SDS development between children with expressive language impairment versus those with receptive-expressive impairment. Sociocultural models of SDS would predict an asymmetry with larger SDS deficits associated with receptive-expressive impairment.
