The direction of attention in second language phonological contrast learning.

This study attempted to describe why some individuals are more successful when learning to perceive the sounds of a second language by analyzing the role attention plays in perceptual learning. Fifty-seven monolingual English-speaking adults completed the study. The participants underwent a perceptual learning paradigm presenting the novel contrast, the voicing contrast between Thai /b/ and /p/. The experiment consisted of a 40-item pretest, 480-trial learning phase, and 40-item posttest. Approximately half of the participants (n = 30) were given explicit instruction to listen for the specific contrast prior to the learning phase; other participants were not told the nature of the contrast. The Attention Network Test (ANT) from Fan, McCandliss, Sommer, Raz, and Posner [(2002). J. Cogn. Neurosci. 14(3), 340-347] was used to assess attentional networks. Generalized linear models and linear mixed effect models (LME) were fit to predict the participants' post-test scores based on ANT subscores, experimental group, and learning block (LME only). The results showed a correlation between attentional control and the ability to learn non-native phoneme contrasts regardless of instruction. In addition, there was a positive interaction between attentional control and the provision of explicit instructions during the learning process, such that individuals with high attentional control learned better when they received explicit instruction prior to training.

Covert contrasts and categorical perception: a comparison of two measurement tools.

This study considers adults' perception of subtle differences in the error productions of /r/ and /l/ in young children. Given that these two phonemes share a common substitution [w], the potential covert contrast between these three sounds was investigated. The utility of two perceptual rating scales was compared: a linear visual analogue scale (VAS) and a triangular scale that considered the possibility of covert contrast among /r,l,w/. Adult listeners rated speech productions from children with cochlear implants (CIs) and speech age-matched children with normal hearing (NH) as they produced VCV or CV productions with /r,l,w/ in syllable-initial position. Mahalanobis distances of the listener ratings for each stimulus on each rating scale were calculated for analysis. Ultimately, there was no difference between the ratings of the two speaker populations. However, there was a significant difference in the amount of variability captured with each scale. The triangular scale reliably captured more variability in the productions than the linear VAS. The significant effect of scale type on the spread of listeners' responses provides support for the claim that the type of rating system used can capture different aspects of a listener's perceptions, thereby suggesting that the type of rating system used in a study may significantly influence that study's findings.

Quantitative Measurement of Communication Ability in Children with Angelman Syndrome.

BACKGROUND: Angelman syndrome is a rare disorder in which most individuals do not develop speech. Testing of communication ability using traditional neuropsychological measures reveals a performance level at or near the floor of the instrument resulting in an inability to detect change when experimental therapeutics are applied. METHODS: Nine individuals, with molecularly confirmed AS, ranging in age from 34 to 126 months, and a single healthy control child (age 16 months) were audio and video-recorded while interacting with a licensed speech-language pathologist in an attempt to elicit vocalization and non-verbal communication. Thirty-minute audio recordings were transcribed and categorized per the Stark Assessment of Early Vocal Development-Revised and a phonetic inventory was created. Using video recordings, gestures were classified by function, either behavioral regulation or social interaction and further categorized as deictic or representational (i.e., behavioral regulation) and joint attention or shared engagement (i.e., social interaction). RESULTS: The range of vocalizations produced by the children with AS was characteristic of children between 0-6 months and none of the children with AS used advanced forms of vocalizations. The mean frequency of reflexive vocalizations, control of phonation and expansion far exceeded the number of uses of canonical syllables, consistant with the characteristics of children around 12 months of age. Most vocalizations were either laughter or isolated vowels, only three children with AS produced consonant-vowel combinations. Children with AS tended to use central and low vowels with few producing high vowels, suggesting the presence of childhood apraxia of speech. CONCLUSION: Our results show the utilization of video-recorded behavioral observations provides a feasible and reliable alternative for quantification of communication ability in this patient population and may be employed during future clinical studies of potential therapeutics.