Risk and protective environmental factors for early bilingual language acquisition

Abstract

Young children's vocabulary skills impact their phonological, semantic and syntactic development (Chiat 2000). It is inevitable, therefore, that small expressive vocabularies showing laboured growth constrain children's language abilities and are associated with delayed language development. Primary language delays occur in the context of otherwise typical development, with a substantial proportion of late talkers recovering spontaneously (Ellis and Thal 2008). In the latter case, vocabulary delays might therefore be a manifestation of a mild neuromaturational lag that can be overcome with adequate stimulation (Henrichs et al. 2011). For those children who do not catch up, however, early vocabulary difficulties would have been the first sign of an unexplained impairment in language-learning capability that implies risk for long-standing academic, emotional and socio-economic consequences (Bishop 2014). There is also evidence that early language delays that appear to resolve might continue to show persistence in the form of subtle vocabulary, grammar and verbal memory difficulties through adolescence (Rescorla 2009, 2013). It is difficult for speech-language therapists to distinguish between children whose delays may resolve and those whose difficulties are likely to persist (Gibbard, Coglan, and MacDonald 2004). Since limited word production in the early years may signal the emergence of a clinically significant condition, it is best considered as a potential warning sign of continuing language impairment (Ellis and Thal 2008). Children at risk for persistent difficulties are best identified early, when they are most likely to benefit from early intervention (Gibbard, Coglan, and MacDonald 2004). Early identification is assisted by the recognition of known risk and protective factors for children's language development (Harrison and McLeod 2010). Despite inconsistencies across studies in identified predictors of language outcome, various environmental factors have been reported as significant to children's language status (see Berkman et al. 2015). In this special issue, the impact of environmental factors is investigated in relation to vocabulary measures obtained from children receiving bilingual exposure. To our knowledge, the evidence available in this field is limited, despite the fact that the majority of children world-wide grow up with more than one input language (Tucker 1998). This collection of papers is therefore timely and should provide much-needed empirical evidence to guide speech-language therapists and other professionals involved with young children's bilingual development. This issue is also 'special' for other reasons. Not only do the studies reported in it involve children exposed to different language pairs in various bilingual contexts, but they also employ a common research design, controlling methodological variables that might otherwise limit the value of cross-linguistic comparisons (see Gatt, O'Toole, and Haman 2015 for a detailed description of the methodological design employed). This volume brings together research carried out within Working Group 3 (Lexical and Phonological Processing) of COST Action 150804 Language Impairment in a Multilingual Society: Linguistic Patterns and the Road to Assessment.