Infant perception of non-native consonant contrasts that adults assimilate in different ways

Numerous findings suggest that non-native speech perception undergoes dramatic changes before the infant's first birthday. Yet the nature and cause of these changes remain uncertain. We evaluated the predictions of several theoretical accounts of developmental change in infants' perception of non-native consonant contrasts. Experiment 1 assessed English-learning infants' discrimination of three isiZulu distinctions that American adults had categorized and discriminated quite differently, consistent with the Perceptual Assimilation Model (PAM: Best, 1995; Best et al., 1988). All involved a distinction employing a single articulatory organ, in this case the larynx. Consistent with all theoretical accounts, 6-8 month olds discriminated all contrasts. However, 10-12 month olds performed more poorly on each, consistent with the Articulatory-Organ-matching hypothesis (AO) derived from PAM and Articulatory Phonology (Studdert-Kennedy & Goldstein, 2003), specifically that older infants should show a decline for non-native distinctions involving a single articulatory organ. However, the results may also be open to other interpretations. The converse AO hypothesis, that non-native between-organ distinctions will remain highly discriminable to older infants, was tested in Experiment 2, using a non-native Tigrinya distinction involving lips versus tongue tip. Both ages discriminated this between-organ contrast well, further supporting the AO hypothesis. Implications for theoretical accounts of infant speech perception are discussed

The Role of Verbal Repetition in the Development of Infant Speech Preferences from 4 to 14 Months of Age

Four experiments investigated infants\u27 preferences for age-appropriate and age-inappropriate infant-directed speech (IDS) over adult-directed speech (ADS). Two initial experiments showed that 6-, 10-, and 14-month-olds preferred IDS directed toward younger infants, and 4-, 8-, 10-, and 14-month-olds, but not 6-month-olds, preferred IDS directed toward older infants. In Experiment 3, 6-month-olds preferred IDS directed toward older infants when the frequency of repeated utterances matched IDS to younger infants. In Experiment 4, 6-month-olds preferred repeated IDS utterances over the same IDS utterances organized without repetition. Attention to repeated utterances precedes word segmentation and sensitivity to statistical cues in continuous speech, and might play a role in the discovery of these and other aspects of linguistic structure

Discrimination of non-native consonant contrasts varying in perceptual assimilation to the listener's native phonological system

Classic non-native speech perception findings suggested that adults have difficulty discriminating segmental distinctions that are not employed contrastively in their own language. However, recent reports indicate a gradient of performance across non-native contrasts, ranging from near-chance to near-ceiling. Current theoretical models argue that such variations reflect systematic effects of experience with phonetic properties of native speech. The present research addressed predictions from Best's perceptual assimilation model (PAM), which incorporates both contrastive phonological and noncontrastive phonetic influences from the native language in its predictions about discrimination levels for diverse types of non-native contrasts. We evaluated the PAM hypotheses that discrimination of a non-native contrast should be near-ceiling if perceived as phonologically equivalent to a native contrast, lower though still quite good if perceived as a phonetic distinction between good versus poor exemplars of a single native consonant, and much lower if both non-native segments are phonetically equivalent in goodness of fit to a single native consonant. Two experiments assessed native English speakers' perception of Zulu and Tigrinya contrasts expected to fit those criteria. Findings supported the PAM predictions, and provided evidence for some perceptual differentiation of phonological, phonetic, and nonlinguistic information in perception of non-native speech. Theoretical implications for non-native speech perception are discussed, and suggestions are made for further research