Late talkers (LTs) exhibit delayed vocabulary development, which might stem from a lack of a typical word learning strategy to generalise object labels by shape, called the ‘shape bias’. We investigated whether LTs can acquire a shape bias and whether this accelerates vocabulary learning. Fourteen LTs were randomly allocated to either a shape training group (Mage = 2.76 years, 6 males), which was taught that objects similar in shape have the same name, or a control group (Mage = 2.61 years, 4 males), which was taught real words without any focus on object shape. After seven training sessions, children in the shape training group generalised trained labels by shape (d = 1.28), but not unfamiliar labels. Children in the control group extended all labels randomly. Training did not affect expressive vocabulary.

Learning new words and, subsequently, a lexicon, is a time-extended process requiring encoding of word-referent pairs, retention of that information, and generalization to other exemplars of the category. Some children, however, fail in one or more of these processes resulting in language delays. The present study examines the abilities of children who vary in vocabulary size (including both children with normal language (NL) and late talking (LT) children) across multiple timescales/processes – known and novel word mapping, novel word retention, and novel noun generalization. Results indicate that children with lower language skills suffer from deficits in quick in-the-moment mapping of known words compared to their NL peers, but age and vocabulary size rather than normative vocabulary ranking or NL/LT status better predicts performance on retention and generalization processes. Implications for understanding language development as a holistic process with multiple interacting variables are discussed.

Children with language disorders have particular difficulty with verbs, but when this difficulty emerges is unknown. We examined syntactic (transitive, intransitive, ditransitive) and semantic (manner, result) features of two-year-olds’ verb vocabularies, contrasting late talkers and typically developing children to look for early differences in verb vocabulary. We conducted a retrospective analysis of parent-reported expressive vocabulary from the Language Development Survey (N = 564, N(LT) = 62) (Rescorla, 1989). Verbs were coded for the presence or absence of each syntactic and semantic feature. Binomial mixed-effects regressions revealed the effect of feature on children's knowledge and whether feature interacted with group classification. Our results revealed mostly similarities between late talkers and typically developing children. All children's vocabularies showed a bias against verbs that occur in ditransitive frames. One feature showed a difference between groups: late talkers showed a bias against manner verbs that typically developing children did not.

This study analyzes the relationship between lexical and grammatical development in Spanish children. The (European) Spanish version of the MacArthur-Bates CDI was used and administered to 593 Spanish-speaking children between the ages of 16 and 30-months-old. Regression analysis was applied to evaluate the relationship between age, vocabulary (total vocabulary, nouns, and verbs) and grammatical scores on two subsections of the Grammar Part. Total vocabulary explained a significantly greater proportion of variance in grammatical outcomes than age did. However, noun and verb vocabularies did not explain a greater proportion of variance in their respective morphologies than total vocabulary did. Additionally, the predictive relationship between vocabulary and grammar was found to be weaker for children whose scores were below the 10th percentile, although this could be due to the minor variability in this group and to extreme cases. We discuss the implications of these results in relation to the question of continuity between early vocabulary and grammar development in children.