Contextual learning of L2 word meanings: second language proficiency modulates behavioural and event-related brain potential (ERP) indicators of learning

ed from multiple episodic memories and can be accessed independently from the original contexts. Successful contextual learning depends on the quality of the linguistic context in which new words are encountered, with little or no contextual learning commonly observed for low-constraint or misleading (inconsistent) contexts (Batterink & Neville, 2011; Borovsky, Elman, & Kutas, 2012; Borovsky, Kutas, & Elman, 2013; Frishkoff, Perfetti, & Collins-Thompson, 2010, 2011; Mestres-Missé, Rodríguez-Fornells, Münte, 2007). In supportive (informative) contexts, when the word meaning is constrained by the surrounding context, a learner may be able to quickly infer the meaning, sometimes from a single exposure. However, this initial knowledge is incomplete and fragile (susceptible to changes and adjustments brought about by additional contextual exposures). Multiple contextual *Corresponding author. Email: [email protected] Language, Cognition and Neuroscience, 2015 Vol. 30, No. 5, 506–528, http://dx.doi.org/10.1080/23273798.2014.942673 © 2014 Taylor & Francis exposures are needed for a robust lexical semantic representation to be established from reading. Robust semantic learning appears to benefit more from exposures to a word in varied than in repeated (same) contexts (Bolger et al., 2008). Varied contexts promote richer semantic associations, help reject false inferences and encourage the establishment of new semantic features (Beck, McKeown, & Kucan, 2002; Rodríguez-Fornells, Cunillera, Mestres-Missé, & de Diego-Balaguer, 2009). Repeating previously encountered contexts, on the other hand, reinforces memories of specific learning episodes and is less likely to support the abstraction of meaning. In summary, contextual word learning is a slow, incremental process, viewed as a longitudinal progression towards context-independent lexical semantic memory representations. The process of establishing robust lexical semantic representations is supported by inter-word connections. By sharing semantic features with other words, a new word becomes part of an existing lexical semantic network (Masson, 1995;McRae, de Sa, & Seidenberg, 1997; Plaut & Booth, 2000). Presumably, learners at lower L2 proficiencies have fewer and weaker L2 lexical semantic connections available and are, therefore, likely to be less effective in establishing L2 lexical semantic representations after initial incidental encounters with novel L2 words during reading. Effects of second language proficiency Previous L2 studies found better contextual learning of word meanings by learners with higher vocabularies (Elgort & Warren, 2014; Ferrel Tekmen & Daloğlu, 2006; Horst, Cobb, & Meara, 1998; Pulido & Hambrick, 2008). This learning advantage may be related to better text comprehension (Pulido, 2007), since vocabulary knowledge and reading comprehension are highly correlated (Jeon & Yamashita, 2014; see Ouellette, 2006, for a similar relationship between vocabulary knowledge and comprehension in L1). L2 proficiency effects extend beyond learning, to words already ‘known’, as revealed by asymmetries in the ways novice and advanced bilinguals access meanings of L2 words (Finkbeiner, Forster, Nicol, & Nakamura, 2004; Kroll & Dijkstra, 2002; Kroll, Michael, Tokowicz, & Dufour, 2002; Wang & Forster, 2010). Phillips, Segalowitz, O’Brien, and Yamasakia (2004) also found that semantic categorisation times for L2 (French) words were more variable for less proficient than more proficient bilinguals, suggesting that semantic processing becomes more automatic at higher L2 proficiency. Neurolinguistic studies (using fMRI and ERP) also show lexical proficiency effects in lexical semantic retrieval and processing. Ardal, Donald, Meuter, Muldrew, and Luce (1990) compared an ERP signature of semantic processing, the N400 component and an accompanying frontal negativity in the first and second language of adult bilinguals (and monolinguals), using congruous and incongruous sentence contexts. Longer N400 latencies in participants’ L2 (compared to their L1) and a significant difference in amplitude between monolinguals and bilinguals at parietal locations were observed. The effect of incongruence at frontal locations was functionally similar to the parietal N400, but it was diminished for the L2. The researchers explained the differences in the latency of the N400 effect by less automatic processing in the L2 compared to the L1, suggesting that ‘N400 latency varies with the relative degree of automaticity achieved in a given language’ (Ardal et al., 1990, p. 201). The reduced effect observed at frontal sites in the bilinguals’ L2 was discussed with reference to their relative fluency of processing in the two languages (which corresponded to their self-reports of being more fluent in the L1 than in the L2). Furthermore, the subgroup of highly fluent bilinguals did not show any reduction in the late negativity in their L2. Later, N400 peak latencies, longer durations and smaller effects were also reported for the less proficient language of bilinguals by Kutas and Kluender (1994; see RodríguezFornells et al., 2009, pp. 3717–3719, for an overview). In a semantic categorisation study, Phillips et al. (2004) found that the N400 distinguished lower from higher proficiency L2 learners when processing associatively related words. Kotz and Elston-Güttler (2004) found similar N400 proficiency differences in semantic category priming. Furthermore, differences between the ERP signature of L1 and L2 lexical processing are modulated by L2 proficiency (Midgley, Holcomb, & Grainger, 2009; Newman, Tremblay, Nichols, Neville, & Ullman, 2012), and fMRI studies show that ‘additional brain activity, mostly in prefrontal areas,’ is involved at lower L2 proficiencies (but not higher L2 proficiencies) in L2 compared to L1 word retrieval (Abutalebi, 2008, p. 471).