ABSTRACT
The main purpose of this chapter is to examine the consequences of different patterns of language switching and use on executive functioning. The Adaptive Control Hypothesis predicts that dual-language context should enhance executive functioning compared to single-language context or dense code-switching. Dual-language contexts were associated with smaller switch costs in some studies, but not with smaller mixing costs or smaller interference costs. The effects of dense code-switching lead to diverse predictions when different types of intra-sentential switches are considered. When a large compositive database is used to identify and select reasonably “pure” case of single-language, dual-language, and dense code-switching bilinguals, no effects of language group were obtained across a wide variety of executive-function tasks. A related question asks whether exposing a bilingual to both languages in the context of performing a nonverbal interference task will automatically trigger domain-general executive functions that enhance performance. A seminal study providing an affirmative answer has been difficult to replicate and new evidence suggests that the benefits of mixing words from two languages also occur if one merely mixes nouns and verbs within a single language.
