Past research has found that bilingual children exhibit an advantage on metalinguistic awareness, the metacognitive ability to reflect on language. However, studies of executive functioning and bilingualism have yielded conflicting results. Given bilinguals need to concentrate on the relevant linguistic system and suppress interference from a second linguistic system simultaneously during processing, they have demonstrated better performance on nonverbal executive tasks involving the choice of two competing perceptual stimuli (interference suppression). However, bilinguals performed no differently on verbal executive tasks that required inhibition of habitual or prepotent responses (response inhibition) than monolinguals. Furthermore, bilinguals have shown weaker vocabulary knowledge in both languages than monolinguals. Thus, the current study hypothesizes that bilingual performance varies in metalinguistic tasks according to task demands on types of executive functioning (interference suppression or response inhibition) and the involvement of linguistic knowledge.

This research aims to analyze the roles of executive control and vocabulary knowledge in metalinguistic tasks in an effort to assess how these two components independently and jointly contribute to metalinguistic development in bilingual and monolingual children. Sixteen English-monolingual 2nd graders and sixteen English-Spanish emerging bilinguals were recruited from a university demonstration school. All students completed four subtests, including Expressive One-Word Picture Vocabulary Test, Color-Shape Task, Zoo Game, and Auditory-visual Selective Attention Task. As expected, this study found bilingual advantage appears differently according to the types of executive control engaged in the metalinguistic tasks. Specifically, emerging bilingual had significantly higher accuracy and less reaction time on the nonverbal metalinguistic tasks involved with response inhibition in relative to monolinguals; meanwhile, there was a bilingual advantage in the number of total responses in the nonverbal interference suppression task. However, emerging bilinguals performed the same as monolinguals did in the verbal interference suppression task. These findings provide new evidences for the diverse effects of bilingualism in the cognitive processing underlying metalinguistic competence.