Project Summary/Abstract
Children’s early vocabulary skills cast a powerful predictive spell over their subsequent language48,96,97 and
educational36,83,143 outcomes. At the same time, bilingual children’s language-specific vocabulary skills lag behind
those of their same-age monolingual peers14,15,49,58,62,87,88,93,97,146,156,160,161,162,164. This lag in language-specific
vocabulary is seen as inevitable and persistent because of distributed exposure of bilingual input across two
languages109,113. The crucial gap in the literature is that the effect of distributed exposure on bilingual
children’s word-learning has not been tested experimentally. The overarching goal of the proposed work
therefore is to test how distributed exposure affects word learning in bilingual children. To this end, we
situate the proposed study within the Cross-Situational Statistical Word Learning (CSWL) framework, where the
formation of links between words and their referents relies on the ability to aggregate statistical information
across multiple exposures to ambiguous mappings between multiple words and referents46,142. Rather than
framing our inquiry in terms of bilingual / monolingual comparisons, we instead harness the CSWL paradigm,
and focus on experimentally manipulating the exposure parameters within the bilingual participants. Our
participants are Spanish-English bilingual toddlers with typical language and who are late to talk, as well
as Spanish-English bilingual children with Developmental Language Disorder (DLD). Specific Aim 1 is to
test the effect of distributed exposure on CSWL in samples of 2-year-old bilingual toddlers enriched for history
of late-talking. In a series of four experiments, we will systematically manipulate exposure parameters, and test
specific, mechanistic hypotheses regarding the effects of these manipulations on children’s CSWL. Specific
Aim 2 is to test the developmental trajectory of distributed-exposure effects and language outcomes in bilingual
children with a history of late-talking. The same children recruited under Specific Aim 1 will be tested again at
age 4, enabling us to examine how learning from distributed exposure changes over time, and identify factors
that predict recovery of expressive language skills in bilingual late-talkers. Specific Aim 3 is to test the effect of
distributed exposure on word learning in 4-year-old bilingual children with DLD. The prediction stemming from
bilingual/monolingual comparisons literature is that distributed exposure will interfere with learning (vs. single-
language exposure). The alternative prediction stemming from theories of CSWL172,174 and from the limited
experimental studies of bilingual learning73,119 is that effects of distributed exposure may be limited, or even
facilitative for bilingual children. Proposed studies will move theories of bilingualism and of CSWL forward by
identifying the specific mechanisms by which distributed exposure does (or do not) impact word learning in
bilingual children. In practical terms, the proposed studies will reveal whether there is an optimal
exposure/intervention strategy for successful acquisition of two languages, and whether it works equally well for
children with typical language skills and for children who are at risk for language impairment.