The ability of 24 Down's syndrome children to act out active and passive semantically biased and neutral sentences in a comprehension task was compared with that of 24 non-retarded children, matched on the basis of their verbal comprehension scores on the Reynell Developmental Language Scale (Reynell, 1969). Down's syndrome children closely resembled control children both in terms of percentage correct responses and in terms of individual children's patterns of error. The results are taken as support for the proposition that the processes underlying language comprehension in the retarded are fundamentally the same as those of non-retarded children. Even so, there was evidence of a slight (6 to 12 months) delay in the appearance of syntactic strategies of comprehension by the Down's syndrome children compared with those non-retarded children matched with them in terms of verbal comprehension age.

In this narrative review, we suggest that children's language skill should be targeted in clinical interventions for children with emotional and behavioral difficulties in the preschool years. We propose that language skill predicts childhood emotional and behavioral problems and this relationship may be mediated by children's self-regulation and emotion understanding skills. In the first sections, we review recent high-quality longitudinal studies which together demonstrate that that children's early language skill predicts: (1) emotional and behavioral problems, and this relationship is stronger than the reverse pattern; (2) self-regulation skill; this pattern may be stronger than the reverse pattern but moderated by child age. Findings also suggest that self-regulation skill mediates the relation between early language skill and children's emotional and behavioral problems. There is insufficient evidence regarding the mediating role of emotion understanding. In subsequent sections, we review evidence demonstrating that: (1) particular kinds of developmentally targeted parent-child conversations play a vital role in the development of language skill, and (2) some current clinical interventions, directly or indirectly, have a beneficial impact on children's vocabulary and narrative skills, but most approaches are ad hoc. Targeting language via parent-child conversation has the potential to improve the outcomes of current clinical interventions in the preschool years.

Young children's language experiences and language outcomes are highly variable. Research in recent decades has focused on understanding the extent to which family socioeconomic status (SES) relates to parents' language input to their children and, subsequently, children's language learning. Here, we first review research demonstrating differences in the quantity and quality of language that children hear across low-, mid-, and high-SES groups, but also-and perhaps more importantly-research showing that differences in input and learning also exist within SES groups. Second, in order to better understand the defining features of 'high-quality' input, we highlight findings from laboratory studies examining specific characteristics of the sounds, words, sentences, and social contexts of child-directed speech (CDS) that influence children's learning. Finally, after narrowing in on these particular features of CDS, we broaden our discussion by considering family and community factors that may constrain parents' ability to participate in high-quality interactions with their young children. A unification of research on SES and CDS will facilitate a more complete understanding of the specific means by which input shapes learning, as well as generate ideas for crafting policies and programs designed to promote children's language outcomes. WIREs Cogn Sci 2016, 7:264-275. doi: 10.1002/wcs.1393 For further resources related to this article, please visit the WIREs website.