This study investigated the comprehension of plural morphosyntactic markers and its relationship with numerical comparison abilities in children with Down syndrome (DS). It evaluated 16 Spanish-speaking children with DS (mean verbal mental age = 3;6) and 16 typically developing children with similar receptive vocabulary (mean chronological age = 3;5). Children participated in two preferential looking tasks assessing their abilities to map singular and plural markers to their visual referents and to distinguish one object from more than one. Results showed that both groups of children correctly mapped plural markers to their referents but failed to map singular ones. Furthermore, results also indicated that both groups also looked at collections of more than one object with four objects but not at those with two. The eye movement patterns of children who looked at collections of more than one object suggest a counting-like strategy. These results indicate that comprehension of plural markers of children with DS is similar to that of their typically developing peers; however, it is not related to their numerical abilities.

Previous studies have demonstrated an effect of early vocal production on infants’ speech processing and later vocabulary. This study focuses on the relationship between vocal production and new word learning. Thirty monolingual Italian-learning infants were recorded at about 11 months, to establish the extent of their consonant production. In parallel, the infants were trained on novel word–object pairs, two consisting of early learned consonants (ELC), two consisting of late learned consonants (LLC). Word learning was assessed through Preferential Looking. The results suggest that vocal production supports word learning: Only children with higher, consistent consonant production attended more to the trained ELC images.