“…In natural language instruction, where training is constant and final proficiency varies, bilinguals outperform monolinguals in learning novel language vocabulary (Cenoz, 2003; Cenoz & Valencia, 1994; Kaushanskaya & Marian, 2009a,b; Keshavarz & Astaneh, 2004; Sanz, 2000; Thomas, 1992; van Hell & Mahn, 1997), grammar (Klein, 1995; Sanz, 2000; Thomas, 1992), and pragmatic rules (Safont Jorda, 2003). Differences in language transfer (MacWhinney, 2007; Murphy, 2003), metalinguistic awareness, (Jessner, 1999, 2008), and phonological working memory (Papagno & Vallar, 1995) are thought to contribute to the bilingual language learning advantage, but by training participants to a proficiency criterion, the effect of these factors on our results is reduced.…”