Finding words and word structure in artificial speech: the development of infants' sensitivity to morphosyntactic regularities

Abstract

To achieve language proficiency, infants must find the building blocks of speech and master the rules governing their legal combinations. However, these problems are linked: words are also built according to rules. Here, we explored early morphosyntactic sensitivity by testing when and how infants could find either words or within-word structure in artificial speech snippets embodying properties of morphological constructions. We show that 12-month-olds use statistical relationships between syllables to extract words from continuous streams, but find word-internal regularities only if the streams are segmented. Seven-month-olds fail both tasks. Thus, 12-month-olds infants possess the resources to analyze the internal composition of words if the speech contains segmentation information. However, 7-month-old infants may not possess them, although they can track several statistical relations. This developmental difference suggests that morphosyntactic sensitivity may require computational resources extending beyond the detection of simple statistics.

Words and possible words in early language acquisition

“…They were not (F(1, 30) = 2.1, P = 0.17). Importantly, studies in our laboratory showed that 12-month-olds familiarized with continuous streams similar to the one used in the current experiments can successfully discriminate words from non-words (Marchetto & Bonatti, 2013). That is, they can extract grouping information from such continuous streams.…”

“…They tested 12-month-olds by creating one segmented stream in which the rule-words were exactly those we used in the current experiments, whereas the non-words selected in the test phase were sogali, femuba, bafemu, and lisoga. Comparing these items with the HF part-words used in the current experiments, one can realize that the items used by Marchetto and Bonatti (2013) differ at most in the position of one single syllable in the non-words. As expected, infants looked longer at the non-words.…”

“…Thus, a less perfect manipulation that still controls for possible baseline preferences consists of constructing familiarizations that maintain the token items in the test phase constant, as much as possible, but makes them become either rule-words or non-words by varying the syllable sequences in the streams. Marchetto and Bonatti (2013) did that with material almost identical to the current test items. They tested 12-month-olds by creating one segmented stream in which the rule-words were exactly those we used in the current experiments, whereas the non-words selected in the test phase were sogali, femuba, bafemu, and lisoga.…”

“…Thus, the role of the test items as rule-words or non-words had an effect, but the specific test items did not. Considering the similarity between the test items used by Marchetto and Bonatti (2013) and those we used in the current experiments, this result makes it highly unlikely that phonotactic, phonetic, or phonological features of the test items or of the familiarization stream we used were the determining factors explaining infants' looking behavior after exposure to a segmented stream.…”

“…We do not know, however, how such productive knowledge of possible words appears nor how it relates to the acquisition of actual words. We do know that very early in development infants can extract rules in different situations, but the role of this ability in the acquisition of linguistic competences in language acquisition is not well understood (Gerken, 2006;Gerken & Bollt, 2008;Gómez & Gerken, 1999;Marchetto & Bonatti, 2013;Marcus, Vijayan, Rao, & Vishton, 1999).…”