This study examined the relation of 3-year core information-processing abilities to lexical growth and development. The core abilities covered four domains--memory, representational competence (cross-modal transfer), processing speed, and attention. Lexical proficiency was assessed at 3 and 13 years with the Peabody Picture Vocabulary Test (PPVT)…

Results question the validity of Cummins's threshold hypothesis and suggest that degree of bilingualism is related to variability in cognitive measures only before a certain threshold of proficiency in the second language is attained. A cause-effect model in which degree of bilingualism appears as the causal factor affecting children's cognitive…