“…As regards L2 acquisition of morphosyntax, many researchers (theorists, acquisitionists, educationalists) are concerned with mental linguistic representations: how they may be similar in L1 and L2 ultimate attainment or maturationally conditioned to be different (e.g., Bley-Vroman, 1989, 2009Jiang, 2004;2007;Lardiere, 2007;Tsimpli & Dimitrakopoulou, 2007;White, 2003). Age effects have been extensively studied (see, e.g., Birdsong, 1992;Bylund, Hyltenstam & Abrahamsson, 2013;Long, 2013;Muñoz & Singleton, 2011;Rothman, 2008). Some argue that features not present in the L1 (at least some) will be unacquirable after a certain age (cf., the Critical Period Hypothesis, Lenenberg, 1967;see, e.g., Franchescina, 2005;Hawkins & Liszka, 2007;Tsimpli & Dimitrakopoulou, 2007, for theoretical linguistic accounts) or ultimately acquirable, but reflecting a developmental sequence different than child L1 acquisition due at least in part to influence of previously acquired linguistic representations (e.g., Schwartz & Sprouse, 1996;White, 2003) and other secondary factors that distinguish children from adults.…”