Brain potentials to native phoneme discrimination reveal the origin of individual differences in learning the sounds of a second language

Abstract

Human beings differ in their ability to master the sounds of their second language (L2). Phonetic training studies have proposed that differences in phonetic learning stem from differences in psychoacoustic abilities rather than speech-specific capabilities. We aimed at finding the origin of individual differences in L2 phonetic acquisition in natural learning contexts. We consider two alternative explanations: a general psychoacoustic origin vs. a speech-specific one. For this purpose, event-related potentials (ERPs) were recorded from two groups of early, proficient Spanish-Catalan bilinguals who differed in their mastery of the Catalan (L2) phonetic contrast /e-/. Brain activity in response to acoustic change detection was recorded in three different conditions involving tones of different length (duration condition), frequency (frequency condition), and presentation order (pattern condition). In addition, neural correlates of speech change detection were also assessed for both native (/o/-/e/) and nonnative (/o/-/ö /) phonetic contrasts (speech condition). Participants' discrimination accuracy, reflected electrically as a mismatch negativity (MMN), was similar between the two groups of participants in the three acoustic conditions. Conversely, the MMN was reduced in poor perceivers (PP) when they were presented with speech sounds. Therefore, our results support a speech-specific origin of individual variability in L2 phonetic mastery. mismatch negativity ͉ event-related potentials ͉ bilingualism L earning a nonnative language sound system is notoriously difficult and often results in the foreign accent that characterizes nonnative speakers. This difficulty in learning a new speech sound system also has consequences for comprehension of the nonnative language. For example, most Japanese native speakers may consider that the English words /rock/ and /lock/ are the same word (1), because the Japanese speech-sound system does not distinguish between the phonemes /r/ and /l/. However, individuals differ significantly in the degree to which they master a nonnative phonetic code, and factors such as the age of acquisition, the amount of exposure, and motivational constraints have a crucial role in final phonetic attainment (2). Despite very early, extended exposure to a L2, many individuals continue to have considerable difficulties in the perception and production of some foreign sounds (3), whereas other nonnative speakers cannot be distinguished from native speakers (4). Discovering the origin of such individual differences is crucial for predicting success in L2 acquisition and for designing learning protocols that maximize the success of L2 learning. To advance in our knowledge of the origin of this individual is the goal of the present study. Specifically, we assess whether such individual differences stem from differences in domain-general psychoacoustic processes or, rather, from differences in specific speech perception abilities.One prolific line of research has explored the neural differences between ind...

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

“…This may have to do with the fact that the magnitude of brain responses, i.e., ERPs to T5 rise time and MMN amplitude lack a speed component, and thus have less in common with one's efficiency of allocating attentional resources. The current findings of contribution of attention to speech processing are compatible with our previous study where visual attention switching could predict tone discrimination efficiency (Ou et al, 2015), as well as research that also found a role of attention in modulating perceptual sensitivity to speech sounds (e.g., Astheimer & Sanders, 2009;Díaz et al, 2008;Jesse & Janse, 2012). The significance of attention switching/ shifting in influencing the distinctiveness of speech representations has been hypothesized in the SAS hypothesis (Hari & Renvall, 2001;Lallier et al, 2010;Ruffino et al, 2010).…”

“…Given that the size of MMN has been found to correlate with individual difference in auditory discrimination ability (e.g. Díaz, Baus, Escera, Costa, & Sebastián-Gallés, 2008;Jakoby, Goldstein, & Faust, 2011), the present findings suggest that auditory discrimination sensitivity, indexed by the MMN, was in general weaker in [-Per-Pro] compared with the other two groups, even to sound contrasts that they could distinguish with high accuracies behaviorally. 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].…”

Auditory perception at the root of language learning

“…Furthermore, auditory brainstem responses in language-impaired children suggest that low-level auditory processes contribute to the pathogenesis of language disorders (4). In adults, individual differences in perceptual abilities correlate with language-processing abilities in their native and a second language (5,6). The findings suggest a potential causal relationship between basic auditory processing ability and the efficiency of language learning in infancy and adulthood.…”

Relationship between individual differences in speech processing and cognitive functions

“…For instance, Parbery-Clark et al (2009) found that the ability to perceive speech in background noise was positively correlated with auditory attention and working memory among individuals differing in musical training. The association of individual differences in speech perception and auditory attentional switching is also shown among L2 learners (Díaz et al, 2008). However, few investigations of individual differences in speech processing have been conducted with native speech perception among typically developed speakers.…”

“…Apart from language disorders, much of the research in speech processing of typically developed speakers has characterized individual differences by employing participants differing in learning/training experience, including second language (L2) learning (Díaz, Baus, Escera, Costa, & Sebastián-Gallés, 2008;Lengeris & Hazan, 2010) and musical training (George & Coch, 2011;Parbery-Clark, Skoe, Lam, & Kraus, 2009) to assess its relationship with cognitive abilities. For instance, Parbery-Clark et al (2009) found that the ability to perceive speech in background noise was positively correlated with auditory attention and working memory among individuals differing in musical training.…”