An ERP Study of Good Production vis-à-vis Poor Perception of Tones in Cantonese: Implications for Top-Down Speech Processing

Abstract

This study investigated a theoretically challenging dissociation between good production and poor perception of tones among neurologically unimpaired native speakers of Cantonese. The dissociation is referred to as the near-merger phenomenon in sociolinguistic studies of sound change. In a passive oddball paradigm, lexical and nonlexical syllables of the T1/T6 and T4/T6 contrasts were presented to elicit the mismatch negativity (MMN) and P3a from two groups of participants, those who could produce and distinguish all tones in the language (Control) and those who could produce all tones but specifically failed to distinguish between T4 and T6 in perception (Dissociation). The presence of MMN to T1/T6 and null response to T4/T6 of lexical syllables in the dissociation group confirmed the near-merger phenomenon. The observation that the control participants exhibited a statistically reliable MMN to lexical syllables of T1/T6, weaker responses to nonlexical syllables of T1/T6 and lexical syllables of T4/T6, and finally null response to nonlexical syllables of T4/T6, suggests the involvement of top-down processing in speech perception. Furthermore, the stronger P3a response of the control group, compared with the dissociation group in the same experimental conditions, may be taken to indicate higher cognitive capability in attention switching, auditory attention or memory in the control participants. This cognitive difference, together with our speculation that constant top-down predictions without complete bottom-up analysis of acoustic signals in speech recognition may reduce one’s sensitivity to small acoustic contrasts, account for the occurrence of dissociation in some individuals but not others.

Cognitive basis of individual differences in speech perception, production and representations: The role of domain general attentional switching

“…Moreover, both the permutation and ANOVA tests confirmed the absence of P3a to T1/T2 in [-Per-Pro], whereas robust P3a components were observed in both [+Per+Pro] and [+Per-Pro]. This finding seems convergent with Law et al (2013), in which individuals with non-distinctive perception of T4/T6 showed a tendency of weaker P3a in all conditions, as compared with controls. The elicitation of P3a depends on sufficient difference between the deviant and the standard stimuli; thus, the P3a is usually described as an index of involuntary switch of attention upon change detection (Berti, Roeber, & Schröger, 2004;Escera, Alho, Winkler, & Näätänen, 1998).…”

“…1. The complex tonal system is reported to be undergoing a sound change-tone merging (Bauer, Cheung, & Cheung, 2003;Fung & Wong, 2010Law, Fung, & Kung, 2013;Lee, Chan, Lam, van Hasselt, & Tong, 2015;Mok, Zuo, & Wong, 2013). Previous studies have shown that, among the six tones, T1 is the most resistant to confusion, while three tone contrasts are merging: T2 vs. T5, T3 vs. T6 and T4 vs. T6.…”

Relationship between individual differences in speech processing and cognitive functions

“…Similar to segmental sounds in many languages of the world (Labov, 1994), this highly complex tone system is in the process of merging, in which particular pairs of tones become less distinctive in perception and/or production. Observations by phonologists and sociolinguists have revealed that three tone contrasts are collapsing: the low-rising and high-rising tones (T2/T5), the mid-level and low-level tones (T3/T6), and low-falling and low-level tones (T4/T6; Bauer, Cheung, & Cheung, 2003;Law, Fung, & Kung, 2013;Mok, Zuo, & Wong, 2013). Specifically, a significant proportion of Cantonese adult speakers can no longer distinguish the two rising tones T2/ T5 in perception and/or production.…”

“…It would be more desirable to use objective tools to assess an individual's cognitive functions. Law et al (2013) examined brain responses to T4 and T6 in Cantonese of two groups of typically developed adult speakers using eventrelated potential (ERP). Behaviorally, both groups of participants could produce all six tones distinctively; they differed only in their perception of the T4/T6 contrast.…”

“…Interestingly, the authors also noticed that the participants who failed to discriminate T4 and T6 perceptually exhibited a tendency of weaker P3a than the controls in all experimental conditions, suggesting a possible difference in attention switching, auditory attention, and/or auditory memory (Polich, 2003). However, the observations in Law et al (2013) remain impressionistic; further evidence for the relationship between variability in speech perception and cognitive abilities is necessary. In the present investigation, three groups of typically developed native speakers of HKC with comparable language and musical backgrounds were recruited.…”