“…To address this question, Sorace and colleagues have proposed the Interface Hypothesis (IH), an influential account within generative approaches to language acquisition, which predicts that morphosyntactic phenomena regulated by discourse–pragmatic conditions are more likely to lead to non-native outcomes than strictly syntactic aspects of the language (see Sorace, 2006, 2011, 2012; Sorace and Filiaci, 2006; Sorace and Serratrice, 2009; Tsimpli and Sorace, 2006; for an overview and critical discussion of the IH, see Montrul, 2011; White, 2011). The predictions of this hypothesis have been tested against different types of bilingual populations (Sorace, 2011), including heritage speakers (Montrul and Polinsky, 2011), with some studies supporting the inherent complexity of the syntax–discourse domain (see, amongst others, Belletti et al, 2007; Flores, 2012; Montrul, 2004; Sorace and Filiaci, 2006; Tsimpli et al, 2004) and others indicating that syntax–discourse phenomena are not predetermined areas for fossilization (see, amongst others, Domínguez, 2013; Donaldson, 2012; Judy, 2015; Judy and Rothman, 2014; Leal et al, 2014; Montrul and Rodríguez-Louro, 2006; Rothman, 2009a).…”