Language exposure predicts infants' neural processing of others' actions based on language group.

What language a person speaks has been shown to divide even infants' worlds. However, open questions remain about what neural processes are involved in the differentiation of native and foreign speakers in the infant's brain. This study used electroencephalography (EEG) to examine the neural responses related to top-down attention (frontal theta synchronization), action processing (mu desynchronization), and approach-avoidance (frontal alpha asymmetry) of 8- to 12-month-old infants as they observed a native (English) speaker and a foreign (French) speaker perform a goal-directed action (i.e., grasping objects). We further examined whether infants' language exposure modulated these neural responses. We found that monolingual infants exhibited stronger mu desynchronization when observing a native (versus foreign) speaker perform goal-directed actions. In contrast, non-monolingual (i.e., hearing more than one language) infants did not show a difference in mu desynchronization between native and foreign speakers. No language group and exposure effects were found for frontal theta and frontal alpha symmetry. These results suggest that infants' emerging differentiation of native and foreign speakers is also manifested in their neural processing of goal-directed actions and that this neural action processing is shaped by early exposure to different languages.