Language Development in English-Spanish Bilingual Children from 22-48 Months: Implications for Assessment Open Access
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Purpose: Using measures of vocabulary, this longitudinal study aimed to explore the course of development of bilingual English-Spanish speaking children at 22, 30 and 48 months, accounting for amount of language input in each language at each age. The study focused on whether those who scored low on early measures of productive vocabulary at 22 and 30 months were at risk for language delay at 48 months and whether bilingual children who fell below a clinically significant cutoff at 22 and 30 months caught up to monolingual age-matched peers at 48 months.Method: Twenty-seven English-Spanish bilingual children and thirty-one monolingual English speaking children were tested on productive vocabulary at 22 and 30 months and receptive vocabulary at 48 months. At 22 and 30 months, parents of monolingual and bilingual children completed the MacArthur-Bates Communicative Development Inventory (CDI) and parents of bilingual children completed the Inventario del Desarollo de Habilidades Comunicativas (IDHC). At 48 months, each child was tested using the Peabody Picture Vocabulary Test-4 (PPVT) and bilingual children were additinally tested on the Test Vocabulario de Imagenes Peabody (TVIP). Relative amount of English input at home was accounted for at each age.Results: Relative amount of English input at home at 22 and 30 months did not predict language outcomes at 48 months. At 22 and 30 months, approximately 50% of the bilingual participants fell below the 16th percentile on the CDI and IDHC. We determined that a measure of Total Vocabulary (TV) was better at predicting PPVT outcomes at 48 months than the single language measures (CDI, IDHC). Using an ROC curve analysis, we identified potential cut-off scores on the CDI and TV at 22 and 30 months to identify children who were likely to score in the average or above average range on the PPVT at 48 months. At 48 months, only one child fell below the 16th percentile on the PPVT; however, as a group, the bilingual children scored significantly lower than the monolingual children on the PPVT.Conclusion: Composite language measures over time must be considered in clinical decision-making. The dual-language measure of TV was a more accurate predictor of receptive vocabulary outcomes at 48 months than single-language measures (CDI, IDHC). While the majority of bilingual English-Spanish children appeared to be delayed at 22 and 30 months, our data showed that most of these children caught up by 48 months.