| Live from the Labs cnrs I international w 8 magazine Paris Early Perceptual Consciousness By Clémentine Wallace w A recent study1 has shown that five-month-old babies might already perceive their environment consciously. “There is this preconceived idea that infants react reflexively to external stimulations and that their sense of consciousness develops later in life. Yet our experiments suggest otherwise,” says lead author Sid Kouider.2 In neurophysiology, the neuronal signature of conscious perception follows a two-step process. During a first unconscious phase, stimuli activate the sensorial regions of the brain. This signal increases with the duration and intensity of exposure. Once it reaches a certain threshold, the information spreads to the prefrontal cortex, responsible for our conscious perception of stimuli. Working with babies and toddlers aged 5, 12, and 15 months, Kouider and his colleagues used highdensity electroencephalography to record the electrical activity inside the brains of 80 infants, who were briefly shown pictures of human faces. Their recordings suggest that the characteristic two-step neuronal signature is also detected in babies. “The only significant difference with adults is that, in babies, the second part of the response—the conscious perception of the stimulus—takes longer to kick in,” explains Kouider. Between 3 and 4 times longer respectively for 12-15 months toddlers and five-month-old babies. In other words, it took them longer to become conscious of what they were seeing. A next step will involve testing these processes during complex learning tasks, such as language acquisition. 01. S. Kouider et al., “A Neural Marker of Perceptual Consciousness in Infants,” Science, 2013. 340: 376-80. 02. Laboratoire de sciences cognitives et psycholinguistique (CNRS / ENS Paris / EHESS). Neurophysiology Contact information: LSC P, Paris. Sid Kouider q A mother holding her five-month-old baby, > sid.kouider@ens.fr who participated in the study. Cognition Language Acquisition in Bilingual Infants of the voice that varies: content words are pronounced at a higher pitch than function words. In this study, researchers demonstrate that in order to differentiate between two languages with such opposite word order structures, bilingual babies rely on these characteristic pitch and duration cues. “Such cues are also used by adults—we can identify some languages by their melody, even without understanding the meaning of words,” says Judit Gervain,2 one of the study’s co-authors. The team worked with seven-monthold babies raised in bilingual or monolingual families, and played an artificial language through speakers placed on both sides of the infants. The language they invented was made up of 20 words, arranged according to two distinct sentence structures mimicking verb- object and object-verb languages, respectively. The language was played By Clémentine Wallace w At just seven months, babies are already capable of distinguishing between two languages with radically different grammatical structures, scientists report.1 The grammatical structure of a language refers to the order of verbs, objects, prepositions, and articles in sentences. English and French are “verb-object languages,” in which verbs come before objects, and function words (articles and prepositions) come before content words. In these languages, content words are emphasized by stressing one syllable, which makes them sound longer compared to the function words that precede them. On the contrary, Japanese, Turkish, or Korean are object-verb languages, in which verbs are placed after the objects, and function words are placed after content words. In this case, it is the pitch with variations either in syllable lengths, or in pitch height. The team measured the time children spent looking at the audio sources in these different conditions—an indication of their interest and attention. They found that bilingual children spent more time looking at an audio source when the melody of the language played matched their “grammatical expectations,” i.e., when verb-object sentence structures were played with variations in word duration, and when those mimicking objectverb grammar were played with variations in pitch. In contrast, monolingual babies showed no difference in looking times—they didn’t pick up on differences in pitch or duration. “These findings show that in order to counter the complexity of acquiring two languages, bilingual q An 8 month-old English-Japanese baby has already started to learn the grammars of both his native languages. © S. Gelsko v
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