Research paper
L1 activation during L2 processing is modulated by both age of acquisition and proficiency

https://doi.org/10.1016/j.jneuroling.2020.100979Get rights and content

Highlights

  • We investigate the roles of AoA and L2 proficiency in cross-language activation during L2 auditory word recognition.

  • In a visual world task, L2 speakers' fixations to the L1 competitor were modulated by both proficiency and AoA.

  • The results suggest that both L2 proficiency and AoA exert effects on cross-language activation.

Abstract

It is well established that access to the bilingual lexicon is non-selective: even in an entirely monolingual context, elements of the non-target language are active. Research has also shown that activation of the non-target language is greater at higher proficiency levels, suggesting that it may be proficiency that drives cross-language lexical activation. At the same time, the potential role of age of acquisition (AoA) in cross-language activation has gone largely unexplored, as most studies have either focused on adult L2 learners or have conflated AoA with L2 proficiency. The present study examines the roles of AoA and L2 proficiency in L2 lexical processing using the visual world paradigm. Participants were a group of early L1 Afrikaans–L2 English bilinguals (AoA 1–9 years) and a control group of L1 English speakers. Importantly, in the bilingual group, AoA and proficiency were not correlated. In the task, participants viewed a screen with four objects on it: a target object, a competitor object whose Afrikaans translation overlapped phonetically with the target object, and two unrelated distractor objects. The results show that the L2 English group was significantly more likely to look at the cross-language competitor than the L1 English group, thus providing evidence of cross-language activation. Importantly, the extent to which this activation occurred was modulated by both L2 proficiency and AoA. These findings suggest that while these two variables may have been confounded in previous research, they actually both exert effects on cross-language activation. The locus of this parallel activation effect is discussed in terms of connectionist models of bilingualism.

Introduction

A vast body of research has shown that the bilingual brain seldom switches off either of its two languages completely: even when operating in a context that is entirely monolingual, elements of the phonology, lexis and syntax of the non-target language are still active (e.g., Bultena, Dijkstra, & van Hell, 2014; Duyck, van Assche, Drieghe, & Hartsuiker, 2007; Grosjean, 1988; Hoshino & Kroll, 2008; Kroll, Bobb, & Wodniecka, 2006; Kroll & Stewart, 1994; Li, 1996; Spivey & Marian, 1999; Vaughan-Evans, Kuipers, Thierry, & Jones, 2014; Wu & Thierry, 2011). What is significant about this so-called cross-language activation is that it seems to be bidirectional (i.e., from the native language to the second language, and vice versa), and also occurs even at moderate levels of proficiency (e.g., van Assche, Duyck, Hartsuiker, & Diependaele, 2009). Given the extent of cross-language activation documented to date in bilingual populations of various profiles, it has been suggested that it is proficiency, rather than the age of acquisition (AoA) of the languages in question, that drives the effect (Kroll, Bobb, & Hoshino, 2014). It is worth asking whether the phenomenon of cross-language activation is indeed unaffected by AoA, which otherwise is known to have a deep impact on bilingual development.

To date, questions of cross-language activation of the lexicon and AoA have received limited attention, as most studies concern adult L2 learners. There are, however, exceptions, and the findings generated within these studies suggest that bilinguals who learnt their L2 later in life are more likely to exhibit L1 activation during L2 lexical processing (e.g., Canseco-Gonzalez et al., 2010). Despite these advances, our current understanding of AoA effects in cross-language activation is constrained by the fact that extant research has not sufficiently disentangled AoA and L2 proficiency. The fact that these two variables are naturally confounded (e.g., Hernandez, 2013; Li, 2013; Monney, Vatz, Morini, Hwang, & DeKeyser, 2013; van Hell & Tanner, 2012) makes it difficult to draw any firm conclusions about whether AoA effects are best understood as a proxy for proficiency effects, or whether they reflect some underlying age-related changes to the way in which the brain processes language. Pursuing this question will thus be informative not only for our understanding of language interaction in the bilingual mind, but also for our knowledge of the scope and mechanisms of AoA effects.

Against this background, the aim of the current study is to examine the roles of both age of L2 acquisition and L2 proficiency in L2 lexical processing. Implementing a visual world paradigm, the study focuses specifically on L1 activation during auditory L2 word recognition in L1 Afrikaans–L2 English bilinguals.

Section snippets

Background

There are hundreds of scholarly studies dedicated to investigating the impact of AoA on L2 learning. The bulk of these studies have, however, focused on the domains of phonetics and syntax, often under the assumption that these represent complex rule-governed systems and are as such more susceptible to AoA effects than the lexicon (because new words can arguably be learnt throughout life). This has left the lexicon, and particularly lexical processing, in the periphery of AoA research. However,

Aims of the current study

Within research on auditory L2 word processing, there is presently no independent evidence regarding the role of AoA. In view of the current literature, at least three different predictions can be made. If it is the case that the preliminary findings of AoA effects in cross-language activation (Canseco-Gonzalez et al., 2010) actually reflect proficiency effects, one would expect that proficiency alone modulates L1 activation during L2 processing. Such an outcome would be consistent with the

Participants

Thirty-one L1 English speakers (mean age = 20.6 years; SD = 1.5 years) and 31 L1 Afrikaans–L2 English speakers (mean age = 22.2 years, SD = 3.6 years) participated in the study.2

Response accuracy and reaction time

Both groups’ response accuracy was high: the L1 English group selected the correct image 99.7% of the time, and the L2 English group 100% of the time. The groups’ reaction times were also comparable (L1 English: mean = 1,187 ms, SD = 385 ms; L2 English: mean = 1,143 ms, SD = 506 ms; p = .69 (t-test)). The critical trials in which participants selected the incorrect image (n = 3; 0.24%) were removed from further analysis.

Time course analyses

Comparison of L1 vs L2 speakers. To determine whether the L2 English

Discussion

The comparison of the L1 and L2 English speakers’ gaze behavior showed firstly that the L2 speakers had more fixations overall in the four areas of interest. This difference was most pronounced in the first 200 ms, and, following Shook and Marian (2019, p. 238), can plausibly be related to the participants’ L2 status: the fact that they were performing the task in their L2 may have made them more likely to fixate on the visual display at the beginning of each trial in order to determine which

Conclusions

In view of the scarcity of empirical evidence on the role of AoA in cross-language activation, the present study set out to examine the influence of this factor along with L2 proficiency on auditory L2 word recognition. The findings showed that the extent to which incoming phonetic information leads to bottom-up activation of L1 lexical items is modulated by both AoA and L2 proficiency. We suggested that the effects of AoA on cross-language activation are driven by the entrenchment of the L1

Author statement

Robyn Berghoff: Conceptualization, software, data curation, formal analysis, writing – original draft preparation, writing – reviewing and editing. Jayde Mcloughlin: Resources, investigation. Emanuel Bylund: Conceptualization, supervision, writing – original draft preparation, writing – reviewing and editing.

Declaration of competing interest

None.

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