Ongoing exposure to an ambient language continues to build implicit knowledge across the lifespan

Recent findings show adult New Zealanders who do not speak te reo Māori (the Māori language, the indigenous language of New Zealand) nonetheless have impressive implicit lexical and phonotactic knowledge of the language. These findings have been interpreted as showing that regular ambient exposure to a non-native language develops an implicit “proto-lexicon”, a memory store of lexical forms in that language, without any meaning. However, what is not known is the timeframe over which this knowledge is acquired. Does the knowledge stem exclusively from implicit learning during childhood, or does it continue to grow based on exposure during adulthood? To investigate this question, we directly compare non-Māori-speaking school-aged adolescents and adults in New Zealand and explore how age affects the degree of observed knowledge. Our results show that ambient exposure leads to implicit knowledge both in childhood and adulthood, and that continuing exposure throughout the lifespan leads to increased knowledge.