Input Subject Diversity Enhances Early Grammatical Growth: Evidence from a Parent-Implemented Intervention

Abstract

Purpose The current study used an intervention design to test the hypothesis that parent input sentences with diverse lexical noun phrase (NP) subjects would accelerate growth in children’s sentence diversity. Method Child growth in third person sentence diversity was modeled from 21 to 30 months (n = 38) in conversational language samples obtained at 21, 24, 27, and 30 months. Treatment parents (n = 19) received instruction on strategies designed to increase lexical NP subjects (e.g., The baby is sleeping.). Instruction consisted of one group education session and two individual coaching sessions which took place when children were approximately 22 to 23 months of age. Results Treatment substantially increased parents’ lexical NP subject tokens and types (ηp2 ≥ .45) compared to controls. Children’s number of different words was a significant predictor of sentence diversity in the analyses of group treatment effects and individual input effects. Treatment condition was not a significant predictor of treatment effects on children’s sentence diversity, but parents’ lexical NP subject types was a significant predictor of children’s sentence diversity growth, even after controlling for children’s number of different words over time. Conclusions These findings establish a link between subject diversity in parent input and children’s early grammatical growth, and the feasibility of using relatively simple strategies to alter this specific grammatical property of parent language input.

What explains the correlation between growth in vocabulary and grammar? New evidence from latent change score analyses of simultaneous bilingual development

“…Dixon and Marchman (2007) similarly allowed that, although their analysis found no evidence of developmental ordering between the lexicon and grammar, finegrained influences might still exist. The present data also do not contradict the notion that a certain threshold of vocabulary knowledge may be necessary for the child to make use of illustrations in input of the grammatical patterns that apply across lexical items (Marchman & Bates, 1994;Hadley et al, 2016) or that a certain level of grammatical development may be necessary in order to make any use of syntactic clues to word meaning (Hollich et al, 2000). The children in the present study were likely to be past those thresholds in both their languages.…”

“…Lexical richness in input clearly supports lexical development (e.g. Hoff, ), and lexical variety in certain grammatical slots may support grammatical inductions (Mintz, ; Naigles & Hoff‐Ginsberg, ; Hadley et al, ). Grammatical complexity of input supports both children's grammatical development (Huttenlocher, Waterfall, Vasilyeva, Vevea, & Hedges, ) and children's vocabulary growth (Hoff, ).…”

The influence of limited scope formulae on children’s subject-copula combinations

“…On the other hand, providing explicit information about objects and surroundings with lexical NP subjects could promote growth in USC by decreasing children's reliance on rote memorization. Recent work has provided evidence that when parents are taught to increase the diversity of their own sentence subjects through other-focused commenting, their children later use more diverse third person subjects themselves and use more adult-like tense and agreement marking compared to peers [45,46].…”

Input Subject Diversity Accelerates the Growth of Tense and Agreement: Indirect Benefits From a Parent-Implemented Intervention

“…In a third study, Hadley et al (2017) used a parentimplemented intervention to manipulate the diversity of sentence subjects in parent input to toddlers with typical development to facilitate sentence development, specifically unique subject-verb combinations. Hadley et al (2017) hypothesized that lexical noun phrase (NP) subjects in parent input would alter cues that signal the boundary between subject and predicate constituents, and this would, in turn, strengthen children's representation of clause structure. Parents received instruction on responsive interaction and language modeling strategies during a 1.5-hr parent group education session and two 1-hr individualized coaching sessions (see the Method section and Hadley et al, 2017, for more details).…”

“…That is, parents varied in how well they learned and delivered the intervention's active ingredient (i.e., the number of different lexical NP subjects in toy talk sentences). Hadley et al (2017) proposed that multiple cues to clause structure were altered by parents' lexical NP subjects in declarative sentences. First, input samples with more low-frequency lexical NP subjects would have lower transitional probabilities or less predictability between the subject and the following verb (e.g., The oven → is hot) than input samples with primarily high-frequency pronominal subjects (e.g., This → is hot).…”