Affect labeling down-regulates amygdala only in a dominant native language

A successful strategy to down-regulate emotions is to simply label them (e.g., saying "I'm sad" when feeling sad). It however remains unresolved which mechanism is responsible for the efficacy of this approach known as affect labeling. Here, we constrain the proposed mechanisms of affect labeling by testing the scope of affect labeling in a new population previously neglected: bilinguals. Specifically, we examined two bilingual groups (Spanish-English, Spanish-Catalan) that varied in language dominance (N = 151). In unbalanced bilinguals, labeling reduced amygdala activity only in the dominant, native language, a pattern reproduced across both bilingual groups. In contrast, and surprisingly, balanced bilinguals showed no amygdala down-regulation in either language. Furthermore, the difference in amygdala activity between languages was larger with a reduced use of the second language. Connectivity analyses paralleled these effects: while the coupling between amygdala-ventrolateral prefrontal cortex was higher during affect labeling in a dominant native language, the relationship reversed in a weak second language. Overall, our findings identify language dominance as a boundary condition on affect labeling and suggest that current theories must incorporate language experience when explaining its neural regulatory effects.