ISCA Workshop on Plasticity in Speech Perception (PSP2005)
Senate House, London, UK
Previous research with pre-linguistic infants has revealed differences in the time course of the perceptual reorganization and categorization processes between infants growing up in monolingual and bilingual environments. For bilinguals, discrimination of target vowel contrasts, which reflect different amount of overlapping and acoustic distance between the two languages of exposure, suggested a U-shaped developmental pattern. A similar trend was observed in infants' ability to discriminate a voicing fricative contrast, present in only one of the languages in their environment. This temporary decline in sensitivity found at 8 months for vowel targets and at 12 months for the voicing contrast suggests the specific perceptual processes that bilingual infants develop in order to deal with their complex linguistic input. Once in the lexical stage, young children growing up in monolingual families have been shown to have wellspecified lexical representations, broadly suggesting a developmental continuity from pre-linguistic sound discrimination capacities and the phonetic detail used in the encoding of early words. However, similar studies concerning simultaneous bilingual acquisition have just begun to be undertaken. Recent research in our laboratory has analyzed young children's sensitivity to different vowel contrasts present in the representation of their first productive lexicon, comparing monolingual and bilingual populations. Children were tested using a visual fixation task: they were presented with sentences that contained nouns for known objects that could be correctly pronounced or mispronounced, while they were shown two pictures simultaneously, but only one was the referent of the utterance. Sensitivity to vowel mispronunciations (lower fixation time and higher orientation latencies to target pictures), would reflect the degree of phonetic detail present in the lexical representation. The mispronunciation effect can also be indicative of the contrastive categories that are functional in the children's phonology. Results from a first series of experiments show interesting differences between monolinguals and bilinguals (18- to 24-month-olds) for vowel contrasts that belong just to one of the languages of exposure. The role of age, number of words in the expressive vocabulary and amount of exposure to each of the languages in the environment, will be considered in the discussion.
Bibliographic reference. Bosch, Laura / Ramon-Casas, Marta / Swingley, Daniel / Sebastián-Gallés, Núria (2005): "Bilingual input and vowel categorization processes: infant and young children data", In PSP2005, 253-256.