Implicit and Explicit Second Language Training Recruit Common Neural Mechanisms for Syntactic Processing

Abstract

In contrast to native language acquisition, adult second language (L2) acquisition occurs under highly variable learning conditions. While most adults acquire their L2 at least partially through explicit instruction, as in a classroom setting, many others acquire their L2 primarily through implicit exposure, as is typical of an immersion environment. Whether these differences in acquisition environment play a role in determining the neural mechanisms that are ultimately recruited to process L2 grammar has not been well characterized. The present study investigated this issue by comparing the event-related potential response to novel L2 syntactic rules acquired under conditions of implicit exposure and explicit instruction, using a novel laboratory language-learning paradigm. Native speakers tested on these stimuli showed a biphasic response to syntactic violations, consisting of an earlier negativity followed by a later P600 effect. After merely an hour of training, both implicitly- and explicitly-trained learners who were capable of detecting grammatical violations also elicited P600 effects. In contrast, learners who were unable to discriminate between grammatically correct and incorrect sentences did not show significant P600 effects. The magnitude of the P600 effect was found to correlate with learners’ behavioral proficiency. Behavioral measures revealed that successful learners from both the implicit and explicit groups gained explicit, verbalizable knowledge about the L2 grammar rules. Taken together, these results indicate that late, controlled mechanisms indexed by the P600 play a crucial role in processing a late-learned L2 grammar, regardless of training condition. These findings underscore the remarkable plasticity of later, attention-dependent processes and their importance in lifelong learning.

Native-language N400 and P600 predict dissociable language-learning abilities in adults

“…The sentence acceptability judgment task we employed is prevalent in the psycholinguistic literature (e.g., Batterink & Neville, 2013; McLaughlin et al, 2010; Osterhout, 1997). In order to find a MAL sentence such as Snehl-ihd noy-ihn peyt-niy acceptable, one must integrate multiple types of linguistic knowledge, including lexical semantics (snehl = woman, noy = rice, peyt = eat), word order (subject-object-verb), and world knowledge (a woman can eat rice).…”

“…A larger N400 amplitude implies more elaborated semantic networks. Previous individual difference studies showed that N400 amplitude (and in some cases, latency) is sensitive to such factors as semantic memory in the native language (Federmeier et al, 2002; Perfetti et al, 2005) and, in a novel language, the degree of language proficiency (Batterink & Neville, 2013; Newman et al, 2012). In children, the N400 has been found to correlate with vocabulary size (Khalifian et al, 2015); interestingly, high vocabulary and verbal fluency seem to serve as protective factors for a subset of older adults whose N400 response pattern, like that of younger adults, evinces predictive facilitation of sentence processing (Federmeier et al, 2002).…”

“…Event-related potentials (ERPs) in response to semantic and syntactic features exhibit distinct temporal and scalp distribution patterns (Hagoort et al, 1993; Kutas & Hillyard, 1984; Osterhout & Holcomb, 1992). Moreover, as individuals’ semantic and syntactic skills improve during foreign-language learning, these ERPs appear to grow more native-like (Batterink & Neville, 2013; Hahne et al, 2006; McLaughlin et al, 2004; McLaughlin et al, 2010; Midgley et al, 2009; Morgan-Short et al, 2012a; Newman et al, 2012; Osterhout et al, 2006; Tanner et al, 2014; Yum et al, 2014). …”

ERPs Recorded during Early Second Language Exposure Predict Syntactic Learning

“…For example, McLaughlin, Osterhout and Kim (2004) found that L2 learners show an N400 effect to L2 pseudowords after 14 hours of classroom instruction. Similarly, a number of studies have demonstrated that L2 learners elicit P600 effects to syntactic violations after relatively short periods of classroom instruction (McLaughlin et al, 2010; Osterhout et al, 2008), or after brief periods of laboratory training (e.g., Mueller et al, 2005; Batterink & Neville, 2013; Davidson & Indefrey, 2008). While these findings have provided important insight into the neural mechanisms underlying L2 processing, such findings characterize the results of learning, rather than the learning process per se.…”

Word segmentation from noise-band vocoded speech

“…And moreover, participants’ anticipation of a test following the familiarisation phase may have led them to engage actively with the incoming speech stream. Regardless, the laboratory context does not reflect language use in real-time communication, which engages a complex combination of active and passive processes when using speech (Batter-ink & Neville, 2013; Morgan-Short, Steinhauer, Sanz, & Ullman, 2012; Norris & Ortega, 2000). We do know that passive exposure in infancy is sufficient for successful word segmentation in lab tasks (Aslin et al, 1998; Graf Estes & Lew-Williams, 2015), but it remains unclear whether passive exposure is sufficient for word segmentation from degraded speech.…”