Consonants and vowels: different roles in early language acquisition

Abstract

Language acquisition involves both acquiring a set of words (i.e. the lexicon) and learning the rules that combine them to form sentences (i.e. syntax). Here, we show that consonants are mainly involved in word processing, whereas vowels are favored for extracting and generalizing structural relations. We demonstrate that such a division of labor between consonants and vowels plays a role in language acquisition. In two very similar experimental paradigms, we show that 12-month-old infants rely more on the consonantal tier when identifying words (Experiment 1), but are better at extracting and generalizing repetition-based srtuctures over the vocalic tier (Experiment 2). These results indicate that infants are able to exploit the functional differences between consonants and vowels at an age when they start acquiring the lexicon, and suggest that basic speech categories are assigned to different learning mechanisms that sustain early language acquisition.

Newborn’s brain activity signals the origin of word memories

“…Therefore, the activations observed in the present study suggest that vowel information is privileged in newborns' encoding and/or recognition of word-sounds. These data contrast with previous studies in adults and older infants, showing that participants rely primarily on consonants during lexical processing and word learning (15)(16)(17)(18)(19)(20)(21)(22)(23).…”

“…Newborns encode the properties of vowels, whereas by the end of the first year, infants start making use of consonants to establish phonological representations of words (23). Although this intriguing developmental change requires further study, it is conceivable that factors, such as the statistical properties of the environmental language (63,64), maturation of areas of the brain implicated in language processing (40,41), as well as the emergence of native consonantal categories (23), contribute to this transition.…”

“…Different studies suggest that in adults (15)(16)(17)(18), and in infants older than 12 mo (19)(20)(21)(22)(23), consonantal sequences are encoded more robustly than vocalic sequences for the representation of words. It is possible that a similar bias (namely, preference for consonantal information when encoding words) is already present at birth.…”

“…[Auditory sensory representations decay in about 1.5 s in newborns (46).] The contrast between the brain responses to consonant and vowel changes enables a comparison of early word-sound memories to more mature word-representations that are known to rely mainly on consonantal information (15)(16)(17)(18)(19)(20)(21)(22)(23). In addition, the present study investigates whether brain areas that support memory for verbal information in adults also support memory in newborn infants.…”

Repetition of words and non-words in typically developing children: The role of prosody

“…However, this functional difference does not seem to be conditioned by consonants being considerably more numerous than vowels in a language (Hochmann, Benavides-Varela, Nespor & Mehler, 2011), and has been observed in e.g. French and English (Nazzi, Floccia, Moquet & Butler, 2009), and Italian (Toro, Nespor, Mehler & Bonatti, 2008), languages that all have different consonant to vowel ratios.…”