Tracking transitional probabilities and segmenting auditory sequences are dissociable processes in adults and neonates |
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Authors: | Lucas Benjamin Ana Fló Marie Palu Shruti Naik Lucia Melloni Ghislaine Dehaene-Lambertz |
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Institution: | 1. Cognitive Neuroimaging Unit, CNRS ERL 9003, INSERM U992, CEA, Université Paris-Saclay, NeuroSpin Center, Gif-sur-Yvette, Île-de-France, France;2. Department of Neuroscience, Max Planck Institute for Empirical Aesthetics, Frankfurt am Main, Hessen, Germany
Department of Neurology, NYU Grossman School of Medicine, New York City, New York, USA |
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Abstract: | Since speech is a continuous stream with no systematic boundaries between words, how do pre-verbal infants manage to discover words? A proposed solution is that they might use the transitional probability between adjacent syllables, which drops at word boundaries. Here, we tested the limits of this mechanism by increasing the size of the word-unit to four syllables, and its automaticity by testing asleep neonates. Using markers of statistical learning in neonates’ EEG, compared to adult behavioral performances in the same task, we confirmed that statistical learning is automatic enough to be efficient even in sleeping neonates. We also revealed that: (1) Successfully tracking transition probabilities (TP) in a sequence is not sufficient to segment it. (2) Prosodic cues, as subtle as subliminal pauses, enable to recover words segmenting capacities. (3) Adults’ and neonates’ capacities to segment streams seem remarkably similar despite the difference of maturation and expertise. Finally, we observed that learning increased the overall similarity of neural responses across infants during exposure to the stream, providing a novel neural marker to monitor learning. Thus, from birth, infants are equipped with adult-like tools, allowing them to extract small coherent word-like units from auditory streams, based on the combination of statistical analyses and auditory parsing cues. Research Highlights - Successfully tracking transitional probabilities in a sequence is not always sufficient to segment it.
- Word segmentation solely based on transitional probability is limited to bi- or tri-syllabic elements.
- Prosodic cues, as subtle as subliminal pauses, enable to recover chunking capacities in sleeping neonates and awake adults for quadriplets.
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Keywords: | EEG language learning neonates prosody sequence learning statistical learning |
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