Assessing Lexical Development in Bilingual Babies and Toddlers

The introduction of vocabulary checklists for infant acquisition has allowed us to gather detailed information about early lexical growth from a broader number of bilingual children than before and to begin exploring the relation of growth in one language to growth in the other in a range of bilingual learning circumstances. Still, no standardized instruments to date give an adequate picture of normal bilingual development. Norms and milestones based on monolingual experience underestimate bilingual abilities in that they tap only a portion of the bilinguals' knowledge and credit them with less complex conceptualizations than what they actually possess. Double-language measures, like those proposed by Pearson, Fernández, and Oller (1993) and Muñoz-Sandoval, Cummins, Alvarado, and Ruef (1998), are an improvement over single-language measures as they encompass a greater portion of the bilinguals' knowledge, but they do not address the greater complexity of bilingual mental representations. What is needed are norms derived from observations of typically-developing bilingual children, followed up with measures of concurrent and predictive validity. However, bilinguals as a group are so diverse, it will be difficult to decide which subgroup(s) would be the appropriate reference to use for a standardization. In this review of recent studies, the difficulties involved in assessing bilingual vocabularies and recommendations for clinical practice are discussed.