From the vast amount of literature on the process of second language acquisition (SLA) in the past decades we can adduce two undeniable facts which are independent of the theoretical framework – that it is complex and that it is highly variable (Ellis, 1994: 139-141; Rothman & Iverson, 2008: 284; Slabakova, 2009: 56). Yet, the consensus on L2 development and acquisition goes no further, since different theoretical stands identify different factors as those that best contribute to a clear explanation of such a complex process. The theoretical debate in the field of SLA has been centred on several specific aspects: (i) the context of acquisition; (ii) the type and quality of input; (iii) language transfer (usually L1); (iv) the existence of a critical period of SLA. One of the most striking characteristics of L2 learners’ interlanguage1 has to do with speech production (Archibald, 1998: 2), a feature of L2 language that is probably the most permeable to L1 transfer (Edwards & Zampini, 2008: 2).