Studies evaluating phonological contrast learning typically investigate either the predictiveness of specific pretraining aptitude measures or the efficacy of different instructional paradigms However, little research considers how these factors interact--whether different students learn better from different types of instruction--and what the psychological basis for any interaction might be The present study demonstrates that successfully learning a foreign-language phonological contrast for pitch depends on an interaction between individual differences in perceptual abilities and the design of the training paradigm Training from stimuli with high acoustic-phonetic variability is generally thought to improve learning; however, we found high-variability training enhanced learning only for individuals with strong perceptual abilities Learners with weaker perceptual abilities were actually impaired by high-variability training relative to a low-variability condition A second experiment assessing variations on the high-variability training design determined that the property of this learning environment most detrimental to perceptually weak learners is the amount of trial-by-trial variability Learners' perceptual limitations can thus override the benefits of high-variability training where trial-by-trial variability in other irrelevant acoustic-phonetic features obfuscates access to the target feature These results demonstrate the importance of considering individual differences in pretraining aptitudes when evaluating the efficacy of any speech training paradigm

http://web.mit.edu/tkp/www/Perrachione-Lee-Ha-Wong_2011_JASA.pdf

Learning a novel phonological contrast depends on interactions between individual differences and training paradigm design

The Revised Speech Learning Model (SLM-r)

Neural changes underlying successful second language word learning: An fMRI study

According to the dual stream model of auditory language processing, the dorsal stream is responsible for mapping sound to articulation and the ventral stream plays the role of mapping sound to meaning. Most researchers agree that the arcuate fasciculus (AF) is the neuroanatomical correlate of the dorsal steam; however, less is known about what constitutes the ventral one. Nevertheless, two hypotheses exist: one suggests that the segment of the AF that terminates in middle temporal gyrus corresponds to the ventral stream, and the other suggests that it is the extreme capsule that underlies this sound-to-meaning pathway. The goal of this study was to evaluate these two competing hypotheses. We trained participants with a sound-to-word learning paradigm in which they learned to use a foreign phonetic contrast for signaling word meaning. Using diffusion tensor imaging, a brain-imaging tool to investigate white matter connectivity in humans, we found that fractional anisotropy in the left parietal–temporal region positively correlated with the performance in sound-to-word learning. In addition, fiber tracking revealed a ventral pathway, composed of the extreme capsule and the inferior longitudinal fasciculus, that mediated auditory comprehension. Our findings provide converging evidence supporting the importance of the ventral steam, an extreme capsule system, in the frontal–temporal language network. Implications for current models of speech processing are also discussed.

https://www.jneurosci.org/content/jneuro/31/24/8780.full.pdf

White matter anisotropy in the ventral language pathway predicts sound-to-word learning success.

A challenge to learning words of a foreign language is encoding nonnative phonemes, a process typically attributed to cortical circuitry. Using multimodal imaging methods [functional magnetic resonance imaging-adaptation (fMRI-A) and auditory brain stem responses (ABR)], we examined the extent to which pretraining pitch encoding in the inferior colliculus (IC), a primary midbrain structure, related to individual variability in learning to successfully use nonnative pitch patterns to distinguish words in American English-speaking adults. fMRI-A indexed the efficiency of pitch representation localized to the IC, whereas ABR quantified midbrain pitch-related activity with millisecond precision. In line with neural “sharpening” models, we found that efficient IC pitch pattern representation (indexed by fMRI) related to superior neural representation of pitch patterns (indexed by ABR), and consequently more successful word learning following sound-to-meaning training. Our results establish a critical role for the IC in speech-sound representation, consistent with the established role for the IC in the representation of communication signals in other animal models.

https://www.physiology.org/doi/pdf/10.1152/jn.00923.2011

Human inferior colliculus activity relates to individual differences in spoken language learning.

Speech sound patterns can be discerned using multiple acoustic cues. The relative weighting of these cues is known to be language-specific. Speech-sound training in adults induces changes in cue-weighting such that relevant acoustic cues are emphasized. In the current study, the extent to which individual variability in cue weighting contributes to differential success in learning to use foreign sound patterns was examined. Sixteen English-speaking adult participants underwent a sound-to-meaning training paradigm, during which they learned to incorporate Mandarin linguistic pitch contours into words. In addition to cognitive tests, measures of pitch pattern discrimination and identification were collected from all participants. Reaction time data from the discrimination task was subjected to 3-way multidimensional scaling to extract dimensions underlying tone perception. Two dimensions relating to pitch height and pitch direction were found to underlie non-native tone space. Good learners attended more to pitch direction relative to poor learners, before and after training. Training increased the ability to identify and label pitch direction. The results demonstrate that variability in the ability to successfully learn to use pitch in lexical contexts can be explained by pre-training differences in cue-weighting.

/pdf/individual-variability-in-cue-weighting-and-lexical-tone-223sqmk5j7.pdf

Padma D. Sampath

Papers

Individual variability in cue-weighting and lexical tone learning