The relative balance between languages predicts the magnitude of whole-language inhibition.

After naming pictures in their second language (L2), bilinguals experience difficulty in naming pictures in their native language (L1). The “L2 after-effect” is a lingering consequence of inhibition applied to L1 to facilitate L2 production. We proposed that the amount of L1 inhibition depends on the relative balance between current activation of L1 and L2. In two experiments, bilinguals performed a blocked picture-naming task which provided a measure of the relative balance between the two languages and indexed whole-language inhibition via the magnitude of the L2 after-effect. The higher the activation level of L1 and the lower the activation level of L2, the bigger the L2 after-effect. The results also reveal an enduring down-regulation of L1 activation level in more language-balanced speakers. The outcomes support the main tenets of the inhibitory account of bilingual language production and indicate a high level of dynamics in the language system.