The roles of pitch type and lexicality in the hemispheric lateralization for lexical tone processing: An ERP study

Previous studies proposed different views to explain the hemispheric lateralization of lexical tone processing. But how the acoustic and phonological information modulates it remains unclear. The acoustic information refers to the physical acoustic features of lexical tones, and the phonological information means the different word meanings differentiated by lexical tones. In the present study, we adopted the active oddball paradigm to explore the effects of pitch type and lexicality on native Cantonese speakers' lexical tone processing with the event-related potential (ERP) technique. We used Cantonese level and contour tones (pitch type) to examine the role of acoustic information and real words and pseudowords (lexicality) to detect the phonological information's effect. The results showed that the pitch type and lexicality affected the N2b amplitudes between the left and right hemispheres interactively, while they did not play roles in P3b amplitudes. The results indicated that the acoustic and phonological information modulated the hemispheric lateralization of lexical tone processing interactively only in the early stage (N2b time window) but not in the later stage (P3b time window). The findings suggested a two-stage model interprets the hemispheric lateralization in lexical tone processing.