There have been many studies exploring the advantages that bilingualism confers to individuals' working memory and metacognition (see Ransdell, 2006; Del Missier et al., 2010). The hypothesis of language critical period states that if no language learning and teaching happen during the critical period, an individual will never be able to fully…

Due to their unique profile as childhood bilinguals whose first language (L1) became weaker than their second language (L2), heritage speakers can shed light on three key issues in bilingualism--timing, input, and cross-linguistic interaction. The heritage speakers of focus in this dissertation are Korean second generation immigrants mainly…