Summary
Language is uniquely human, but its acquisition may involve cognitive capacities shared with other species [1-5]. During development, language experience alters speech sound (phoneme) categorization [6-8]. Newborn infants distinguish the phonemes in all languages, but by 10 months show adult-like greater sensitivity to native language phonemic contrasts than non-native contrasts [8, 9]. Distributional theories account for phonetic learning by positing that infants infer category boundaries from modal distributions of speech sounds along acoustic continua [10, 11]. For example, tokens of the sounds /b/ and /p/ cluster around different mean voice onset times. To disambiguate overlapping distributions, contextual theories propose that phonetic category learning is informed by higher-level patterns (e.g. words) in which phonemes normally occur [12-15]. For example, the vowel sounds /I/ and /e/ can occupy similar perceptual spaces, but can be distinguished in the context of “with” and “well”. Both distributional and contextual cues appear to function in speech acquisition [10-12, 16-21]. Non-human species also benefit from distributional cues for category learning [22-24], but whether category learning benefits from contextual information in non-human animals is unknown. The use of higher-level patterns to guide lower-level category learning may reflect uniquely human capacities tied to language acquisition, or more general learning abilities reflecting shared neurobiological mechanisms. Using songbirds, European starlings, we show that higher-level pattern learning covertly enhances categorization of the natural communication sounds. This observation mirrors the support for contextual theories of phonemic category learning in humans, and demonstrates a general form of learning not unique to humans or language.