Introduction

Acknowledging Lenneberg's (1967) Critical Period Hypothesis or Seliger's (1978) milder differential fossilisation hypothesis the implication is that once a certain age has been reached by the learner, with reduced (if any) access to Universal Grammar (UG), the grammatical system of a foreign language will never be internalised without the crutch of formal instruction. While a child can acquire languages in a way parallel to his/her mother tongue and become a truly multilingual speaker, the adult no longer has the same capacity to acquire an L 2 naturally and automatically . This has been borne out by a body of research indicating that adults who have found themselves in an immersion situation (immigrants, sojourners) never acquire full linguistic competence without the benefit of additional methodical learning; moreover, some fail dismally without developing even rudimentary grammatical competence (e.g. failing to apply morphological endings). Seliger (1978) believes that different levels of language processing (syntax and pronunciation, for instance) are linked to distinct neural mechanisms, with the result that various aspects of language fossilise at different periods (learners with native-like syntax but foreign pronunciation are not uncommon). The process of the lateralisation of macroneural circuits and localisation of language functions is gradual and lengthy, with different aspects of language affected at different stages, and only several becoming unacquirable after puberty (phonology doubtless being most noticeable and therefore frequently quoted – cf. the 'Henry Kissinger effect' alias 'Joseph Conrad phenomenon'; but vide Cummins (1981), Fullana and Muñoz (2003), García Lecumberri and Gallardo (2003) or Leather (2003) for findings that – in a formal context – early exposure does not correlate to a 'near-native' accent). An explanation of why no advantage in pronunciation is observed in the adult learner may be that this aspect of language is probably least amenable to conscious manipulation.