Effects of proceduralization of an L2 on cognitive abilities: looking for the threshold of bilingual benefits

Much recent research in the fields of SLA and Bilingualismhas focused on the social, linguistic, and cognitive benefits ofbilingualism (Cook, 1997; Bialystok, 2001; Bialystok, 2004;Sanz, 2000; Sanz, 2007). This research has sought to establishthe nature of these benefits and the point at which they emerge.Cummins’ Threshold Theory posits that these benefits aredetermined by level of proficiency in both languages (Cummins, 1976). This threshold, however, has not been adequatelyoperationalized. Based on the Declarative/Procedural model inL2 speakers (Ullman, 2001a; Ullman, 2005), we hypothesizedthat the onset of use of procedural memory in both languagesmarks the emergence of cognitive benefits for bilinguals. In apreliminary attempt to investigate this effect, we measured theverbal and non-verbal memory of participants before and afterlearning an artificial language to high proficiency. ERP measureswere used to determine reliance on procedural memory duringL2 language processing. The results indicate that the use ofprocedural memory during L2 language processing may affectnon-verbal memory measures; no effects were found for verbalmemory measures. Contrary to the hypothesis, however, theparticipants who used procedural memory showed lower scoreson these measures than those who did not use proceduralmemory. These results suggest that procedural memory andnon-verbal memory may be related.