INtersensory Cooperation in phonological DEvelopment

Project Information

INCODE

Grant agreement ID: 895484

DOI

10.3030/895484

Project closed

EC signature date 20 April 2020

Start date 4 January 2021

End date 3 July 2023

Funded under

• EXCELLENT SCIENCE - Marie Skłodowska-Curie Actions

Total cost

€ 196 707,84

EU contribution

€ 196 707,84

Coordinated by

UNIVERSITE PARIS CITE
France

Periodic Reporting for period 1 - INCODE (INtersensory Cooperation in phonological DEvelopment)

Reporting period: 2021-01-04 to 2023-01-03

Summary of the context and overall objectives of the project

During the first year of life, infants learn to recognize and produce speech sounds. Proficiency in these phases is crucial for later linguistic and educational outcomes.
The main achievements accomplished by infants in this period have been unveiled. Yet, the sensory bases of these processes are still unclear.
Spoken language is a complex signal entailing the action of phono-articulation and its resulting sound (speech). Traditionally, speech perception has been regarded as an auditory-based ability. However, evidence has shown that speech actions do also carry perceptual correlates. In adults, the brain network recruited by speech processing includes the sensorimotor areas underlying speech production (Skipper, Devlin & Lametti, 2017), co-activation testifying of a strict action/perception association. Thus, contemporary investigations on language development cannot neglect sensorimotor processes: this would amount to ignore the ontogenesis of a sensory channel that is active in adults. Evidence on the function of sensorimotor processes in early speech development is still poor (Vilain et al., 2019). However, infancy constitutes an ideal context of investigation, as during this period the anatomy and neurocognitive control of the speech sensorimotor apparatus begins its maturation (Guellaï, Streri & Yeung, 2014): when, how, why do sensorimotor processes begin to play a perceptual role, in language? Which advantages are carried by this intersensory binding?
Recent studies have shown that, once infants have learnt to produce a given speech sound, they also display a boost in its perception (ex. Vilain et al., 2019; DePaolis et al., 2010, Lorenzini & Nazzi, 2022). More surprisingly, another series of studies have also shown that, before the onset of production, infants can recruit sensorimotor information for perceptual purposes if they are put under appropriate conditions (infant-friendly manipulations of the articulatory organs, Choi et al., 2021). This results prove the existence of precocious sensorimotor processes in language development and suggest that the sensorimotor system might play an important role in language learning. More studies are needed to detail the functional role possibly played by sensorimotor processes in the context of early linguistic achievements.
INCODE aims to shed light on these research questions as follows.
Experiment 1: is there a relationship between speech-related sensorimotor development and the processing of speech sounds? In particular: is there a link between infants' abilities to articulate consonant sounds and their rapidity in developing perceptual biases concerning consonant processing (ex., Nishibayashi & Nazzi, 2016. https://doi.org/10.1016/j.cognition.2016.07.003)?
Experiment 2: can we identify changes in the neural correlates of speech sounds processing before and after speech-related sensorimotor knowledge is developed, through the onset of babbling?

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

Experiment 1:
Infants’ articulatory productivity has been correlated with the development of speech perception, including: preferences for listening to certain speech sounds (e.g. DePaolis et al., 2011) and the ability to categorizing phonemes (Vilain et al., 2019). Recent work that has linked articulatory productivity with word recognition and learning (Lorenzini & Nazzi, 2022; Hoareau, Yeung & Nazzi, 2019). We ask whether articulatory-motor productivity is also linked to the emergence of consonant-vowel perceptual biases. In most languages, consonants outnumber vowels. Speakers of such languages show a perceptual bias for consonants (C-bias) when segmenting, learning and recognizing word-forms (Nazzi & Cutler, 2019). The C-bias emerges in the first year of life, preceded by a V-bias, suggesting that such biases depend on infants’ experience with native language (Nishibayashi & Nazzi, 2016). Auditory experience is assumed to be critical, vowels being more perceivable than consonants since before birth. However, articulatory-motor experience might also be at play. We asked how infants’ shift from a V-bias to a C-bias is linked to two measures of articulatory-motor productivity: experience producing consonants, or more general vocal reactivity (speech and non-speech vocalizations).In a looking-time paradigm, 32 French-learning infants listened to passages containing CVC words, followed by mispronunciations of these words (identical to target-words except for one V or C). If the C-bias is present, infants look longer to V-mispronunciations; if the V-bias is present, infants look longer to C-mispronunciations. In parallel, we investigated articulatory-motor productivity through human-annotated home recordings and the Vocal Reactivity scale of the Infant Behavior Questionnaire. Statistical analyses revealed that infants who vocalized more had a greater C-bias only if they also had wider production inventories: in brief, vocal productivity has to be linguistic in nature to be linked to the development of consonant-vowel perceptual biases.

Experiment 2.
Improvements in the perception of specific speech sounds have been detected following the onset of production of those same sounds (DePaolis et al., 2011). These results led to the hypothesis that babbling leads to a perceptual reorganization setting-up action/perception links. However, such results have only been observed behaviorally, based on the analysis of attentional patterns. Despite indirect neurofunctional evidence (Imada et al., 2006), we do not know whether the perceptual improvements linked to babbling onset represent the signs of an actual neurofunctional reorganization. 

In an ERP study, we compare electrophysiological signatures of speech sound processing before and after these same speech sounds are practiced in babbling. Babbling is home-recorded from each participant and analyzed based on human perceptual judgment.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

Experiment 1 adds to literature on how speech production influences speech development. It is the first study to show that articulatory skills predict consonant-vowel perceptual biases in word segmentation, critically important for understanding what constellation of skills support basic word segmentation skills.
Experiment 2, once completed, might have a considerable impact in the field of study, as it directly tests the hypothesis that the onset of speech production modifies the neurofunctional patterns underlying speech sound perception.
Both experiments highlight the importance to stimulate and valorize sensorimotor maturation in infancy. Secondly, they are indirectly relevant for the study of Speech Sound Disorders. (SSDs). Occurring with an estimated prevalence of 3,6% of total school-aged population, SSDs comprise heterogeneous conditions (e.g. phonological disorder, stuttering, childhood apraxia of speech) sharing the common feature of a jeopardized speech-sensorimotor development. Clinical literature has underlined phonological/perceptual deficits in SSDs but these are not considered as a core-feature of such conditions. The discovery of precocious action/perception links in typical phonological development can encourage research on perception in this field, and boost rehabilitation.
INCODE also carries implications for second language (L2) learning, entailing a re-evaluation of the relevance of the (correct) production of the L2 sounds for their perception.

Experiment 1. Relationship between general oromotor entrainment and consonant perception (ANOVA)