The Interface Between Implicit and Explicit Knowledge in Second Language Acquisition

<jats:title>Abstract</jats:title> <jats:p>This entry examines the relationship between explicit (conscious) and implicit (unconscious) second language (L2) knowledge. Debates in SLA research have long centered on whether explicit knowledge impacts implicit knowledge development, particularly in instructional contexts. These debates have been framed using the metaphor of an interface—a direct influence of and exchange of information between the two knowledge types. Three camps emerged: the noninterface position (which theorizes no direct influence), the weak interface position (proposing an indirect influence), and the strong interface position (which emphasizes automatization of explicit knowledge). Although each of the three camps has emphasized different aspects of the learning and acquisition process, ultimately, the commonalities between them are greater than what distinguishes them. Furthermore, recent scholarship is beginning to reframe these debates, highlighting, first, that influences between these knowledge types are bidirectional and, second, that the nature of the influences, whether direct or indirect, matters greatly. Research has emerged in four promising areas: (a) the impact of explicit instruction on real‐time L2 processing; (b) the simultaneous development of implicit and explicit knowledge; (c) the impact of implicit knowledge on explicit knowledge; and (d) improving measurement tools, particularly for implicit and automatized explicit knowledge. Based on a synthesis of this body of work to date, instructed L2 learning is likely to benefit from a balanced approach to explicit and implicit instruction, prioritizing the development of implicit knowledge and incorporating explicit attention to language regularities when this explicit knowledge is likely to be facilitative of subsequent implicit knowledge development.</jats:p>