Academic literature on the topic 'Early language acquisition'

The relationship between sleep and language during infancy has not attracted a great deal of scrutiny despite its theoretical importance in the function of sleep and the practical implications to which resulting findings could contribute. With this in mind, the current thesis aims to investigate this question with a focus on word learning, generalisation of word meanings and vocabulary development. A cross-sectional design in 16 month old infants was used as one of the main approaches to test the potential effects of naps on word learning and generalisation. In both experiments, infants were randomly assigned to nap or wake conditions. After teaching two novel object-pairs to them, their initial performance was tested with an intermodal preferential looking task. An increase in target preference indicated the recognition of the auditory label-looking behaviour being monitored with an automatic eye-tracker. In the case of word learning, the same objects were shown in the test trials as in the training trials, whereas the test objects were different in colour in the generalisation experiment. In both experiments target preference increased only after a nap, while there was no change in the performance of the wake groups. These results indicate that daytime napping facilitates both the consolidation of novel words and the generalisation of novel word meanings in infancy. The relationship between sleep and vocabulary development was studied in a longitudinal questionnaire based design, in which vocabulary questionnaires and sleep diaries were employed, with a cohort of 246 children between the ages of 7 and 38 months being analysed. Sleep measures were used as predictors in a multi-level growth curve analysis of vocabulary development. The length of daytime naps was positively correlated with both expressive and receptive vocabulary growth, whereas the length of night-time sleep was negatively associated with rate of expressive vocabulary growth. To conclude, the results of the present thesis highlight the importance of daytime naps in early childhood.

Learning language is a cornerstone in the cognitive development during the first year of life. A fundamental difference between infants growing up in monolingual versus bilingual environments is the necessity of the latter to discriminate between two language systems since very early in life. To be able to learn two different languages, bilingual infants will have to perceive the regularities of each of their two languages while keeping them separated. In this thesis we explore the differences between monolingual and bilingual infants in their early language discrimination abilities as well as the strategies that arise for each group as a consequence of their adaptation to their different linguistic environments. In chapter two, we examine the capacities of monolingual and bilingual 4-month-old infants to discriminate between their native/dominant language from foreign ones in the auditory domain. Our results show that, in this context, bilingual and monolingual infants present different brain signals, both in the temporal and the frequency domain, when listening to their native language. The results pinpoint that discriminating the native language represents a higher cognitive cost for bilingual than for monolingual infants when only auditory information is available. In chapter three we explore the abilities of monolingual and bilingual 8-month-old infants to discriminate between languages in the visual domain. Here we show to infants never exposed to sign languages videos of two different sign languages and we measure their discriminatory abilities using a habituation paradigm. The results show that at this age only bilingual infants can discriminate between the two sign languages. The results of a second control study points in the direction that bilinguals exploit the information coming from the face of the signer to make the distinction. Altogether, the studies presented in this thesis investigate a fundamental ability to learn language - specially in the case of bilingual environments - which is discriminating between different languages. Compared to a monolingual environment, being exposed to a bilingual environment is characterized by receiving more information (2 languages) but with less exposure to each of the languages (on average half of the time to each of them). We argue that the developmental brain is as prepared to learn one language from birth, as it is to learn two. However, to do so, monolingual and bilingual infants will develop particular strategies that will allow them to select the relevant information from the auditory and visual domains.<br>La adquisición del lenguaje es una pieza fundamental en el desarrollo cognitivo durante el primer año de vida. Una diferencia fundamental entre los bebés que crecen en ambientes monolingües y bilingües es que estos últimos necesitan discriminar entre dos sistemas lingüísticos desde muy temprano en la vida. Para poder aprender dos idiomas, los bebés bilingües tienen que percibir las regularidades de cada uno de sus idiomas y a la vez mantenerlos separados. En esta tesis exploramos las diferencias entre bebés monolingües y bilingües tanto en sus capacidades de discriminación tempranas, como en las estrategias que desarrolla cada grupo como consecuencia de la adaptación a su entorno lingüístico. En el segundo capítulo, examinamos la capacidad de los bebés bilingües y monolingües a los 4 meses de edad para discriminar entre la lengua nativa/dominante de otra extranjera en el dominio auditivo. Nuestros resultados muestran que, en este contexto, los bebés monolingües y bilingües presentan diferentes señales auditivas cuando escuchan su lengua nativa. Los resultados señalan que discriminar la lengua nativa representa un coste cognitivo mayor para los bebés bilingües que para los monolingües cuando sólo sólo disponen de información auditiva. En el capítulo 3, exploramos las habilidades de los bebés monolingües y bilingües a los 8 meses de edad para discriminar lenguas en el dominio visual. Aquí, mostramos a bebés que nunca han sido expuestos a lengua de signos, videos de dos lenguas de signos diferentes y medimos sus habilidades discriminatorias usando un paradigma de habituación. Los resultados muestran que a esta edad sólo los bebés bilingües son capaces de hacer la distinción y apuntan que para ello aprovechan la información proveniente de la cara de la signante.