A cross-linguistic examination of toddlers' interpretation of vowel duration

Developmental change in English-learning children's interpretations of salient pitch contours in word learning

To efficiently recognize words, children learning an intonational language like English should avoid interpreting pitch-contour variation as signaling lexical contrast, despite the relevance of pitch at other levels of structure. Thus far, the developmental time-course with which English-learning children rule out pitch as a contrastive feature has been incompletely characterized. Prior studies have tested diverse lexical contrasts and have not tested beyond 30 months. To specify the developmental trajectory over a broader age range, we extended a prior study (Quam & Swingley, 2010), in which 30-month-olds and adults disregarded pitch changes, but attended to vowel changes, in newly learned words. Using the same phonological contrasts, we tested 3- to 5-year-olds, 24-month-olds, and 18-month-olds. The older two groups were tested using the language-guided-looking method. The oldest group attended to vowels but not pitch. Surprisingly, 24-month-olds ignored not just pitch but sometimes vowels as well-conflicting with prior findings of phonological constraint at 24 months. The youngest group was tested using the Switch habituation method, half with additional phonetic variability in training. Eighteen-month-olds learned both pitch-contrasted and vowel-contrasted words, whether or not additional variability was present. Thus, native-language phonological constraint was not evidenced prior to 30 months (Quam & Swingley, 2010). We contextualize our findings within other recent work in this area.

Showing strength through flexibility: Multi-accent toddlers recognize words quickly and efficiently

One of the great mysteries of language acquisition is how children cope with variation in their input. If one parent says pah-tah-to and the other parent says pah-tay-to, how does this affect a child's speech processing development? Past research suggests variableinput may have negative effects on the efficiency of multi-accent children'swordrecognition, leading to slower word recognition compared to mono-accent children, and even failure to recognize words in their parent's non-dominant accent. Here, were-examine speed ofwordrecognitionina large sample of Dutch-learning 24-month-olds (n = 96) who receive routine exposure to one versus two varieties of their native language.. We conclude that multi-accent children are equipped to flexibly adapt to their variable speech input, and show no language delay at 24 months of age. Contrary to earlier reports, we find no evidence that exposure to multiple varieties has long-lasting detrimental effects ontoddler's wordrecognition efficiency.

Learning phonology from surface distributions, considering Dutch and English vowel duration

In learning language, children must discover how to interpret the linguistic significance of phonetic variation. On some accounts, receptive phonology is grounded in perceptual learning of phonetic categories from phonetic distributions drawn over the infant's sample of speech. On other accounts, receptive phonology is instead based on phonetic generalizations over the words in the lexicon. Tests of these hypotheses have been rare and indirect, usually making use of idealized estimates of phonetic variation. Here we evaluated these hypotheses, using as our test case English and Dutch toddlers' different interpretation of the lexical significance of vowel duration. Analysis of thousands of vowels of one Dutch and three English mothers' speech suggests that children's language-specific differences in interpretation of vowel duration are likely due to detection of lexically specific patterns, rather than bimodality in raw phonetic distributions.