Speaking Two Languages for the Price of One: Bypassing Language Control Mechanisms via Accessibility-Driven Switches

How do bilinguals switch easily between languages in everyday conversation, even though studies have consistently found that switching slows responses? In previous work, researchers have not considered that although switches may happen for different reasons, only some switches-including those typically studied in laboratory experiments-might be costly. Using a repeated picture-naming task, we found that bilinguals can maintain and use two languages as efficiently as a single language, switching between them frequently without any cost, if they switch only when a word is more accessible in the other language. These results suggest that language switch costs arise during lexical selection, that top-down language control mechanisms can be suspended, and that language-mixing efficiency can be strategically increased with instruction. Thus, bilinguals might switch languages spontaneously because doing so is not always costly, and there appears to be greater flexibility and efficiency in the cognitive mechanisms that enable switching than previously assumed.