“…It has also been attested among aphasics and in first-language acquisition, although transitorily in the case of the latter (for discussion, see, for example, Avrutin, 2004). In recent years, researchers in multilingualism have taken a particular interest in optionality, noting its presence among child second-language (L2) acquirers (Pladevall Ballester, 2010), adult L2 acquirers (Sorace, 1999, 2000a; White, 1992), and among bilingual Heritage Speakers in the United States (de Prada Pérez and Pascual y Cabo, 2012; Silva-Corvalán, 1994). It also forms a crucial part of the Interface Hypothesis (IH, e.g.…”