| Second language learning has received much widespread attention from researchers, educators and parents. As with first language acquisition, word learning in a second language is a building block for further language development. Whereas many studies on bilingualism indicate that an infant's capacity for vocabulary acquisition seems to extend to two languages from birth (Byers-Heinlein, 2010; Genesee & Nicoladis, 2007; Ng & Wigglesworth, 2007; Reynolds, 1991) and much applied research has been dedicated to teaching second language vocabulary to children and adults, very few studies have directly compared the differences between children's and adult's second language word learning. The effect of age on second language learning is highly controversial. This dissertation aims to address the question of whether early or late is better for learning words in a second language by examining the interaction between age and exposure approach. The current studies are designed to explore different exposure approaches for teaching words in a second language to monolingual learners of different ages. I approach this question by focusing on second language word learning through three studies, each examining one exposure approach for English-speaking monolinguals learning words in a second language (i.e., Mandarin) by: 1) providing translation equivalents; 2) mere exposure to natural second language input with a single event context; 3) mere exposure to natural second language input with multiple event contexts. These three approaches were examined with three different groups of monolingual English-speaking learners: 28-30 months olds, 5-6 year olds and young adults. This dissertation was also interested in whether the effectiveness of these approaches may depend on the native language experience or other cognitive capacities of the learners. Results found that adults responded more accurately and quickly than children, with no difference across exposure approaches. Both groups of children, in contrast, performed differently with different exposure approaches. They were able to successfully fast-map words to the referents only in the Mandarin-only approach with a single event context. Furthermore, adults' foreign language aptitude and working memory were significant correlated with their performance in these laboratory studies of second language word learning. |
