Majority language skill, not measures of bilingualism, predicts executive attention in bilingual children

Evidence is mixed regarding whether and why bilingual children might be advantaged in the development of executive functions. Five preregistered hypotheses regarding sources of a bilingual advantage were tested with data from 102 Spanish-English bilingual children and 25 English monolingual children who were administered a test of executive attention, the flanker task, at 7, 8, and 9 years of age. Measures of the children's early and concurrent bilingual exposure and their concurrent English and Spanish skill were available from a larger longitudinal study in which these children participated. Tests of the preregistered hypotheses yielded null findings: The bilingual children's executive attention abilities were unrelated to their amount of early exposure to mixed input, to balance in their early dual language exposure, to balance in their concurrent exposure, to their degree of bilingualism, or to their combined Spanish + English vocabulary score. English vocabulary score was a positive significant correlate of executive attention among the bilingual children, but those bilingual children above the group median in English vocabulary did not outperform the monolingual children when the comparison was adjusted for nonverbal IQ. These findings suggest that a language learning ability may explain the association between bilingualism and executive function. Because the best statistical approach to testing for effects on differences is a matter of dispute, all analyses were conducted with both a difference score and a residual gain score as the outcome variable. The central findings, but not all findings, were the same with both approaches.