On the edge of language acquisition: inherent constraints on encoding multisyllabic sequences in the neonate brain

Abstract

To understand language, humans must encode information from rapid, sequential streams of syllables - tracking their order and organizing them into words, phrases, and sentences. We used Near-Infrared Spectroscopy (NIRS) to determine whether human neonates are born with the capacity to track the positions of syllables in multisyllabic sequences. After familiarization with a six-syllable sequence, the neonate brain responded to the change (as shown by an increase in oxy-hemoglobin) when the two edge syllables switched positions but not when two middle syllables switched positions (Experiment 1), indicating that they encoded the syllables at the edges of sequences better than those in the middle. Moreover, when a 25 ms pause was inserted between the middle syllables as a segmentation cue, neonates' brains were sensitive to the change (Experiment 2), indicating that subtle cues in speech can signal a boundary, with enhanced encoding of the syllables located at the edges of that boundary. These findings suggest that neonates' brains can encode information from multisyllabic sequences and that this encoding is constrained. Moreover, subtle segmentation cues in a sequence of syllables provide a mechanism with which to accurately encode positional information from longer sequences. Tracking the order of syllables is necessary to understand language and our results suggest that the foundations for this encoding are present at birth.

Newborns are sensitive to multiple cues for word segmentation in continuous speech

“…The differential response was evident in the anterior channels, consistent with previous studies using similar protocols (Benavides-Varela et al, 2011Ferry et al, 2016;Nakano et al, 2009). While precise anatomical information is unavailable, these anterior channels were placed to cover temporal, frontal, and F I G U R E 2 Responses during test blocks for Experiment 1.…”

“…We expected a robust response spanning across multiple channels over frontal-temporal areas (Ferry et al, 2016;Nakano et al, 2009), thus, we placed the pads trying to maximize the coverage of those areas. The probes on each side of the head mean that we can investigate lateralization effects.…”

“…Data were pre-processed using custom functions and functions of the Homer2 NIRS package (Huppert, Diamond, Franceschini, & Boas, 2009) Carlson, & Mujica-Parodi, 2011;Ferry et al, 2016;Peña et al, 2003). (1) We identified saturated samples (intensity was greater than 5 a.u.)…”

The specificity of the neural response to speech at birth

“…This type of analysis defines regions of interest (ROIs) in a non-arbitrary, data-driven, yet anatomically informed fashion, and has been used successfully in the past with infant NIRS data (Ferry et al, 2015;Mahmoudzadeh et al, 2013). We implemented the cluster-based permutation test using the same parameters as in Ferry et al (2015).…”

Do infants retain the statistics of a statistical learning experience? Insights from a developmental cognitive neuroscience perspective

“…These findings countered the prevailing thought of the time that infant learning was too rudimentary to explain how children learn language in the span of a few short years, that instead language must develop according to a special language programme. Thus, despite continued debate about the nature of learning in language acquisition [3][4][5], there is now widespread appreciation for the fact that children rely on a variety of mechanisms to acquire language, not all innately determined or specific to language. There are also now many such presentations at the BUCLD and many important publications of SL in children and adults.…”