Protracted development on native tone interpretation: Evidence from Mandarin-learning infants’ novel word learning

Two habituation-switch experiments were conducted to explore whether Mandarin-learning infants could exploit tonal cues during their word learning, and detect a change when the association of two word-object pairs was switched. We found that when two words were solely differentiated by their lexical tones, Mandarin-learning infants failed to detect the switch of tones at 14 months, but succeeded at 18 months. However, when two words were remarkably distinct, infants could detect the change of words as early as 14 months. The results indicate that infants may not refer to the lexical function of tone during their novel word learning until 18 months, even though infants from birth are able to distinguish the tonal contrast.