Bouchon, C. 1, 2, 3 , Nazzi, T. 1, 2, 3 & Gervain, J. 1, 2, 3
1 University Paris Descartes ? Laboratoire de Psychologie de la Perception UMR 8158
2 CNRS ? UMR 8158
3 LabEx Empirical Foundations of Linguistics
Consonants (Cs) carry more information at the lexical level, and vowels (Vs) at the morphosyntactic level (Nespor, et al. 2003). This ?division of labour? would constitute a significant learning bias towards lexical and morphosyntactic acquisition. While adults use these biases, infants? data are more mixed but a consonantal bias has been observed at 12 and 8 months (Hochmann et al., 2011; Nishibayashi & Nazzi, 2012). However, in a lexical task, 6?month?olds exhibited a vocalic bias (Hochmann, 2010) suggesting that a certain amount of speech exposure is necessary before infants use the C/V functional asymmetry. This study investigates the origins of the C/V functional asymmetry through rule detection at birth (a proxy for syntax), by measuring newborns? brain responses with NIRS, when exposed to a speech signal carrying a repetition of Vs or Cs. The extraction and generalization of a repetition pattern carried by syllables (ABB vs. ABC sequences) in CVCVCVs sequences are crucial for rule learning, and present at 7.5 months (Marcus et al., 1999). Precursors of this mechanism are present at birth (Gervain et al. 2008; 2011). The stimuli consisted of CVCVCVs implementing 3 different rules: ABC, (e.g. ?mulevi?); ABBc, (e.g. ?muleli?); ABBv, (e.g. ?muleve?). The division of labor predicts that if presented in a blocked?design with blocks of different sequences (6 items) the elicited rule extraction process would favor the ABBv rule over other rules. Results of 24 newborns showed that ROIs (fronto?temporal and parieto?temporal) in both hemispheres are differently involved depending on the condition. ABBv evoked a stronger left response in fronto? and superiortemporal channels, suggesting a perceptual bias towards the detection of repetition carried by Vs vs. Cs. We are currently conducting additional experiments to further explore whether these results reflect the origins of the C/V asymmetry.