Spanish-English bilingual toddlers’ vocabulary skills: The role of caregiver language input and warmth

There is a well-documented link between bilingual language development and the relative amounts of exposure to each language. Less is known about the role of quality indicators of caregiver-child interactions in bilingual homes, including caregiver input diversity, warmth and sensitivity. This longitudinal study examines the relation between caregiver input (lexical diversity, amount), warmth and sensitivity and bilingual toddlers’ subsequent vocabulary outcomes. We video-recorded caregiver-child interactions in Spanish-English Latino homes when toddlers (n = 47) were 18 months of age (M = 18.32 months; SD = 1.02 months). At the 24-month follow-up, we measured children's vocabulary as total vocabulary (English, Spanish combined) as well as within language (Spanish, English). Results revealed that Spanish lexical diversity exposure at 18 months from caregivers was positively associated with children's Spanish and total vocabulary scores at 24 months, while English lexical diversity was positively associated with children's English scores; lexical diversity and amount were highly correlated. Additionally, caregivers’ warmth was positively associated with children's Spanish, English and total vocabulary scores. Together, these factors accounted for substantial variance (30–40%) in vocabulary outcomes. Notably, caregiver input accounted for more variance in single language outcomes than did caregiver warmth, whereas caregiver warmth uniquely accounted for more variance in total vocabulary scores. Our findings extend prior research findings by suggesting that children's dual language development may depend on their exposure to a diverse set of words, not only amount of language exposure, as well as warm interactions with caregivers. A video abstract of this article can be viewed at https://youtu.be/q1V_7fz5wog

Highlights

• Video-recorded observations of caregiver-child interactions revealed warmth and high sensitivity from Latino caregivers.
• Linguistically-detailed analyses of caregiver input revealed wide variation in the diversity of Spanish and English directed at 18-month-old bilingual toddlers.
• Bilingual toddlers’ vocabulary (single language, total) was positively associated with caregivers’ diverse input and warmth, thus extending prior findings on bilinguals’ amount of language exposure.
• Findings suggest that caregivers’ lexical diversity explains more variance in bilingual toddlers’ single language outcomes, whereas warmth explains more variance in total vocabulary scores.

     

A Computational and Empirical Investigation of Graphemes in Reading

It is often assumed that graphemes are a crucial level of orthographic representation above letters. Current connectionist models of reading, however, do not address how the mapping from letters to graphemes is learned. One major challenge for computational modeling is therefore developing a model that learns this mapping and can assign the graphemes to linguistically meaningful categories such as the onset, vowel, and coda of a syllable. Here, we present a model that learns to do this in English for strings of any letter length and any number of syllables. The model is evaluated on error rates and further validated on the results of a behavioral experiment designed to examine ambiguities in the processing of graphemes. The results show that the model (a) chooses graphemes from letter strings with a high level of accuracy, even when trained on only a small portion of the English lexicon; (b) chooses a similar set of graphemes as people do in situations where different graphemes can potentially be selected; (c) predicts orthographic effects on segmentation which are found in human data; and (d) can be readily integrated into a full‐blown model of multi‐syllabic reading aloud such as CDP++ (Perry, Ziegler, & Zorzi, 2010). Altogether, these results suggest that the model provides a plausible hypothesis for the kind of computations that underlie the use of graphemes in skilled reading.