Phonetic learning as a pathway to language: new data and native language magnet theory expanded (NLM-e)

<jats:p>Infants' speech perception skills show a dual change towards the end of the first year of life. Not only does non-native speech perception decline, as often shown, but native language speech perception skills show improvement, reflecting a facilitative effect of experience with native language. The mechanism underlying change at this point in development, and the relationship between the change in native and non-native speech perception, is of theoretical interest. As shown in new data presented here, at the cusp of this developmental change, infants' native and non-native phonetic perception skills predict later language ability, but in opposite directions. Better<jats:italic>native</jats:italic>language skill at 7.5 months of age predicts faster language advancement, whereas better<jats:italic>non-native</jats:italic>language skill predicts slower advancement. We suggest that native language phonetic performance is indicative of<jats:italic>neural commitment</jats:italic>to the native language, while non-native phonetic performance reveals<jats:italic>un</jats:italic>committed neural circuitry. This paper has three goals: (i) to review existing models of phonetic perception development, (ii) to present new event-related potential data showing that native and non-native phonetic perception at 7.5 months of age predicts language growth over the next 2 years, and (iii) to describe a revised version of our previous model, the native language magnet model, expanded (NLM-e). NLM-e incorporates five new principles. Specific testable predictions for future research programmes are described.</jats:p>