Aging of lexical selection and phonological encoding in Chinese spoken word production: An EEG study.

Using a picture-word interference paradigm combined with electroencephalography (EEG), this study investigated how healthy aging affects the temporal dynamics of lexical selection and phonological encoding during spoken word production. Younger and older adults named pictures while word frequency, syllable frequency, and phonological relatedness between targets and distractors were systematically manipulated. Behaviorally, older adults exhibited larger word frequency and syllable frequency effects but reduced phonological facilitation relative to younger adults, indicating age-related changes in both lexical and phonological processing. ERP analyses revealed stage-dependent age differences across successive stages of lexical selection, phonological encoding, and phonetic encoding. Although both groups showed sensitivity to lexical frequency, older adults exhibited reduced and temporally altered neural sensitivity to lexical frequency during early and intermediate processing, alongside increased influence of phonological distractors. Both groups continued to exhibit lexical-phonological interactions during later phonetic encoding. ERP decoding and temporal generalization analyses revealed relatively preserved word-frequency representations across age groups, whereas syllable-frequency and phonological-facilitation representations emerged later and were less temporally stable in older adults. These findings indicate that healthy aging affects both lexical and phonological processing, with more pronounced alterations in the timing and temporal stability of phonological representations. Age-related differences extended across multiple stages of spoken word production. The pattern of increased sensitivity to phonological competition and reduced stability of phonological representations is consistent with the inhibitory deficit hypothesis and the transmission deficit hypothesis, respectively, suggesting that age-related changes in spoken word production arise from both less efficient phonological transmission and reduced control over competing phonological information.