Sleep-based memory processing facilitates grammatical generalization: Evidence from targeted memory reactivation

• Participants learned the grammar of an artificial language and then napped.
• Phrases from the language or control stimuli were covertly presented during sleep.
• Participants cued on the phrases showed gains in grammatical generalization.
• Gains were driven by enhancements in rule abstraction and not item memory strength.
• Learning related to grammatical generalization can be biased during sleep.

Generalization—the ability to abstract regularities from specific examples and apply them to novel instances—is an essential component of language acquisition. Generalization not only depends on exposure to input during wake, but may also improve offline during sleep. Here we examined whether targeted memory reactivation during sleep can influence grammatical generalization. Participants gradually acquired the grammatical rules of an artificial language through an interactive learning procedure. Then, phrases from the language (experimental group) or stimuli from an unrelated task (control group) were covertly presented during an afternoon nap. Compared to control participants, participants re-exposed to the language during sleep showed larger gains in grammatical generalization. Sleep cues produced a bias, not necessarily a pure gain, suggesting that the capacity for memory replay during sleep is limited. We conclude that grammatical generalization was biased by auditory cueing during sleep, and by extension, that sleep likely influences grammatical generalization in general.