Setting the “tone” first and then integrating it into the syllable: An EEG investigation of the time course of lexical tone and syllable encoding in Mandarin word production

• We observed facilitation for Homophonous primes but interference for Tonal primes in naming latencies of Mandarin words; • The tonal relatedness effect emerged alone before the syllabic relatedness effect in early stimulus-locked ERPs; • An interaction effect between tonal and syllabic relatedness was found in later ERPs; • The ERP data support a two-stage model: an early independent retrieval of tone and a later tone-to-syllable integration. Lexical tone is an important phonological property in tonal languages, but its encoding process in speech production remains unclear. We conducted two electroencephalographic (EEG) experiments to investigate the time course of tonal encoding relative to that of syllabic encoding in Mandarin Chinese disyllabic and monosyllabic word production respectively. We employed a phonologically primed picture naming task and orthogonally manipulated the tonal and syllabic overlap between the prime and the target word. In both experiments, the ERP data revealed that the main effect of tonal relatedness began to emerge alone in an early time window before that of syllabic relatedness, indicating an early independent retrieval process for lexical tone. Moreover, we observed a significant interaction between tonal and syllabic relatedness in later ERP time window(s) and onset latencies, indicating a later tone-to-syllable integration process. These results support the two-stage model of tonal encoding in Mandarin word production and offer implications for current speech production models.