A universal cue for grammatical categories in the input to children: Frequent frames

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Data from typologically diverse languages shows common distributional patterns.

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Discontinuous repetitive patterns in the input provide cues for category assignment.

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Morphological frames accurately predict nouns and verbs in the input to children.

How does a child map words to grammatical categories when words are not overtly marked either lexically or prosodically? Recent language acquisition theories have proposed that distributional information encoded in sequences of words or morphemes might play a central role in forming grammatical classes. To test this proposal, we analyze child-directed speech from seven typologically diverse languages to simulate maximum variation in the structures of the world’s languages. We ask whether the input to children contains cues for assigning syntactic categories in frequent frames, which are frequently occurring nonadjacent sequences of words or morphemes. In accord with aggregated results from previous studies on individual languages, we find that frequent word frames do not provide a robust distributional pattern for accurately predicting grammatical categories. However, our results show that frames are extremely accurate cues cross-linguistically at the morpheme level. We theorize that the nonadjacent dependency pattern captured by frequent frames is a universal anchor point for learners on the morphological level to detect and categorize grammatical categories. Whether frames also play a role on higher linguistic levels such as words is determined by grammatical features of the individual language.

Detecting structured repetition in child-surrounding speech: Evidence from maximally diverse languages

Caretakers tend to repeat themselves when speaking to children, either to clarify their message or to redirect wandering attention. This repetition also appears to support language learning. For example, words that are heard more frequently tend to be produced earlier by young children. However, pure repetition only goes so far; some variation between utterances is necessary to support acquisition of a fully productive grammar. When individual words or morphemes are repeated, but embedded in different lexical and syntactic contexts, the child has more information about how these forms may be used and combined. Corpus analysis has shown that these partial repetitions frequently occur in clusters, which have been coined variation sets. More recent research has introduced algorithms that can extract these variation sets automatically from corpora with the goal of measuring their relative prevalence across ages and languages. Longitudinal analyses have revealed that rates of variation sets tend to decrease as children get older. We extend this research in several ways. First, we consider a maximally diverse sample of languages, both genealogically and geographically, to test the generalizability of developmental trends. Second, we compare multiple levels of repetition, both words and morphemes, to account for typological differences in how information is encoded. Third, we consider several additional measures of development to account for deficiencies in age as a measure of linguistic aptitude. Fourth, we examine whether the levels of repetition found in child-surrounding speech is greater or less than what would have been expected by chance. This analysis produced a new measure, redundancy, which captures how repetitive speech is on average given how repeititive it could have been. Fifth, we compare rates of repetition in child-surrounding and adult-directed speech to test whether variation sets are especially prevalent in child-surrounding speech. We find that (1) some languages show increases in repetition over development, (2) true estimates of variation sets are generally lower than or equal to random baselines, (3) these patterns are largely convergent across developmental indices, and (4) adult-directed speech is reliably less redundant, though in some cases more repetitive, than child-surrounding speech. These results are discussed with respect to features of the corpora, typological properties of the languages, and differential rates of change in repetition and redundancy over children's development.