Reassessing the electrophysiological evidence for categorical perception of Mandarin lexical tone: ERP evidence from native and naïve non-native Mandarin listeners

Some studies have argued that native speakers of tonal languages have been shown to perceive lexical tone continua in a more categorical manner than speakers of non-tonal languages. Among these, Zhang and colleagues (NeuroReport 23 (1): 35-9) conducted an event-related potential (ERP) study using an oddball paradigm showing that native Mandarin speakers exhibit different sensitivity to deviant tones that cross category boundaries compared to deviants that belong to the same category as the standard. Other recent ERP findings examining consonant voicing categories question whether perception is truly categorical. The current study investigated these discrepant findings by replicating and extending the Zhang et al. study. Native Mandarin speakers and naïve English speakers performed an auditory oddball detection test while ERPs were recorded. Naïve English speakers were included to test for language experience effects. We found that Mandarin speakers and English speakers demonstrated qualitatively similar responses, in that both groups showed a larger N2 to the across-category deviant and a larger P3 to the within-category deviant. The N2/P3 pattern also did not differ in scalp topography for the within- versus across-category deviants, as was reported by Zhang et al. Cross-language differences surfaced in behavioral results, where Mandarin speakers showed better discrimination for the across-category deviant, but English speakers showed better discrimination for within-category deviants, though all results were near-ceiling. Our results therefore support models suggesting that listeners remain sensitive to gradient acoustic differences in speech even when they have learned phonological categories along an acoustic dimension.