Aging and distributional tone learning: the role of pitch memory in older adults’ discrimination of mandarin lexical tones

Distributional learning enables listeners to form phonetic categories by extracting statistical regularities from speech input. Younger Cantonese speakers can acquire the Mandarin level-falling (T1–T4) contrast through distributional learning, with bimodal exposure facilitating category formation and unimodal exposure suppressing it, and with fine-grained pitch sensitivity predicting success. However, aging is associated with declines in pitch sensitivity and phonetic boundary formation, which may disrupt this process. This study examined whether Cantonese-speaking older adults exhibit distributional learning of Mandarin T1–T4 and whether individual cognitive factors predict learning success. Sixty-four participants completed a pretest–training–posttest procedure with bimodal or unimodal exposure. While older adults improved in tone discrimination, no group differences emerged. Further analysis showed that those with lower pitch-related auditory memory failed to learn from unimodal input. On the other hand, fine-grained pitch perception abilities did not predict learning outcomes. These results suggest that older adults may rely on alternative learning mechanisms, such as memory-based strategies, when exposed to ambiguous input distributions. The findings indicate a shift from perceptual encoding to memory-driven processing in aging and highlight the limits of passive statistical learning in older adulthood.