# LEARNING A NON-NATIVE LANGUAGE IN A NATURALISTIC ENVIRONMENT: INSIGHTS FROM BEHAVIOURAL AND NEUROIMAGING RESEARCH

EDITED BY: Christos Pliatsikas and Vicky Chondrogianni PUBLISHED IN: Frontiers in Psychology

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ISSN 1664-8714 ISBN 978-2-88919-639-5 DOI 10.3389/978-2-88919-639-5

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## **LEARNING A NON-NATIVE LANGUAGE IN A NATURALISTIC ENVIRONMENT: INSIGHTS FROM BEHAVIOURAL AND NEUROIMAGING RESEARCH**

Topic Editors: **Christos Pliatsikas,** University of Kent, UK **Vicky Chondrogianni,** University of Edinburgh, UK

It is largely accepted in the relevant literature that successful learning of one or more non-native languages is affected by a number of factors that are independent of the target language(s) per se; these factors include the age of acquisition (AoA) of the target language(s), the type and amount of formal instruction the learners have received, as well as the amount of language use that the learners demonstrate. Recent experimental evidence suggests that one crucial factor for efficient native-like performance in the non-native language is the amount of naturalistic exposure, or immersion, that the learners receive to that language. This can be broadly defined as the degree to which language learners use their non-native language outside the classroom and for their day-to-day activities, and usually presupposes that the learners live in an environment where their non-native language is exclusively or mostly used.

Existing literature has suggested that linguistic immersion can be beneficial for lexical and semantic acquisition in a non-native language, as well as for non-native morphological and syntactic processing. More recent evidence has also suggested that naturalistic learning of a non-native language can also have an impact on the patterns of brain activity underlying language processing, as well as on the structure of brain regions that are involved, expressed as changes in the grey matter structure.

This Research Topic brings together studies on the effects of learning and speaking a nonnative language in a naturalistic environment. These include more efficient or "native-like" processing in behavioural tasks tapping on language (lexicon, morphology, syntax), as well as changes in the brain structure and function, as revealed by neuroimaging studies.

**Citation:** Pliatsikas, C., Chondrogianni, V., eds. (2015). Learning a Non-Native Language in a Naturalistic Environment: Insights from Behavioural and Neuroimaging Research. Lausanne: Frontiers Media. doi: 10.3389/978-2-88919-639-5

# Table of Contents

## Editorial: Learning a non-native language in a naturalistic environment: insights from behavioral and neuroimaging research

Christos Pliatsikas 1 \* and Vicky Chondrogianni 2

*1 School of Psychology, University of Kent, Canterbury, UK, 2 School of Philosophy, Psychology and Language Sciences, University of Edinburgh, Edinburgh, UK*

#### Keywords: bilingualism, second language acquisition, immersion

Research on bilingualism has boomed in the past two decades. The processes by which a second language is acquired and processed has been investigated via linguistic, psycholinguistic, and neurolinguistic perspectives, focusing not only on second language (L2) acquisition and processing, but also the effects it might have on cognition and brain structure and function (Bialystok et al., 2012). More recent studies have focused on the effects of experience-based factors on L2 acquisition and processing (Dussias and Piñar, 2009); for example, several studies have increasingly focused on how L2 processing is affected by the active and continuous use of L2, or immersion, whether it becomes native-like, and which language domains are particularly affected (Dussias and Sagarra, 2007; Pliatsikas and Marinis, 2013). The present E-Book is a collection of recent studies that demonstrate the effects of immersive L2 learning in lexical, phonological and morphosyntactic processing, while at the same time discusses the potential effects of immersive non-native acquisition on the structure of the bilingual brain.

Several studies in this E-Book have focused on morpho-syntactic processing by immersed late L2 learners. In an ERP study, Carrasco-Ortiz and Frenck-Mestre (2014) showed that highly proficient L2 learners of French with limited immersion (5–6 months) were native-like in their sensitivity of detecting verbal inflectional errors. This sensitivity was enhanced in the presence of phonological cues to the errors, but was also dependent on the L2 learner's overall proficiency. Further evidence in the domain of morpho-syntax was provided in an ERP experiment by Meulman et al. (2014), who demonstrated that immersed (5 years) late Romance learners of Dutch were native-like in detecting auditorily-presented verb agreement violations in non-finite verbs, but not gender violations. This demonstrated that there might be limits to how native-like L2 processing can be, but these limits are specific to the grammatical construction under investigation.

In two behavioral masked lexical priming experiments and in an ERP study with advanced Spanish and German late L2 learners of English, De Cat et al. (2015) showed that lexically transparent noun-noun compounds (NNCs) such as moon dust are processed combinatorially by advanced non-native speakers similarly to native speakers; however, sensitivity to word order violations within the NNCs was modulated by the learners' L1.

In an acceptability judgment task, Parafita Couto et al. (2015) examined the interaction between word order and focus in the context of unaccusative (e.g., arrive) and unergative (e.g., walk) verbs in Spanish in a group of English late L2 learners of Spanish with extensive naturalistic exposure to L2 input. Immersed late L2 learners accepted different word order patterns depending on the focus context; however, they failed to distinguish between unaccusative and unergative verbs, and the ability to do so was a function of the verb's frequency rather than its categorical classification on

#### Edited and reviewed by:

*Manuel Carreiras, Basque Center on Cognition, Brain and Language, Spain*

> \*Correspondence: *Christos Pliatsikas<EMAIL_ADDRESS>
#### Specialty section:

*This article was submitted to Language Sciences, a section of the journal Frontiers in Psychology*

Received: *29 June 2015* Accepted: *06 July 2015* Published: *17 July 2015*

#### Citation:

*Pliatsikas C and Chondrogianni V (2015) Editorial: Learning a non-native language in a naturalistic environment: insights from behavioral and neuroimaging research. Front. Psychol. 6:1009. doi: 10.3389/fpsyg.2015.01009* the basis of unaccusativity. At the same time, L2 learners were less categorical in their judgments compared to monolingual speakers.

In terms of lexical recognition, in two behavioral experiments, Casaponsa et al. (2014) demonstrated that immersed balanced and unbalanced Spanish-Basque bilinguals were equally efficient in recognizing L2-specific bigrams, suggesting that bilingual immersion can lead to native-like orthographic processing; however, these effects were modulated by the participants' L2 proficiency.

Zinszer et al. (2014) tested Chinese-English bilinguals in China and in the US on a lexical categorization task and examined which L2 learner's language history variables (length of immersion, L2 training, age of L2 onset, and code-switching patterns) and language variables (e.g., native speaker agreement on picture naming) predict performance on this task. The authors reported that words with high name agreement and few alternate names elicited high performance; at the same time, immersion, age of L2 onset and code-switching patterns contributed positively to learners' performance, whereas years of L2 training had a negative impact on task performance.

The effects of exposure to naturalistic L2 input on vocabulary learning were examined in two studies by Dahl and Vulchanova (2014) and by Vulchanova et al. (2015). Dahl and Vulchanova examined whether providing naturalistic L2 exposure within a standard school curriculum influences comprehension of vocabulary in two groups of 6-year-old Norwegian-speaking children. After 8 months of exposure, the group that received naturalistic input to English outside the classroom setting but within the school context outperformed on vocabulary learning the group that was only exposed to English within the classroom setting. This suggests that increased exposure to the L2 can lead to a significant increase in receptive vocabulary at this young age even after a short period.

Vulchanova et al. (2015) examined short- and long-term memory effects of first language (L1) and L2 subtitles on text comprehension and vocabulary learning in two groups of adolescent Norwegian learners of English. Short-term effects of L1 and L2 subtitles on text comprehension were found in both groups. These effects were modulated by vocabulary knowledge in the younger group of L2 learners and by knowledge of grammar in the older L2 group. There were no long-term effects in either group on vocabulary learning as measured through a word definition task and lexical decision task. Participants' extracurricular activities such as reading and writing in the L2, exposure to L2 media and games also emerged as significant predictors of the L2 learners' comprehension abilities.

In terms of phonological processing, Gor (2014) demonstrated that heritage English-Russian speakers (early naturalistic interrupted learners) of high proficiency in Russian, were equally efficient to native speakers of Russian in processing speech in noise. This demonstrated the early benefits of immersed L2 learning, which appear to persevere even when immersion is interrupted.

Although the existing behavioral and ERP literature appears to argue for substantial effects of immersion on bilinguals' performance, its effects on brain structure are proven more difficult to capture and describe. In an opinion article, Sharwood Smith (2014) discusses the issues in combining linguistic, psychological and neuroimaging approaches in the search for a unified theory of bilingual processing. In reviewing the neurolinguistic literature, Stein et al. (2014) argue that the reported structural effects of bilingualism on the gray matter (GM) and white matter (WM) of the brain cannot be safely attributed to the type or amount of L2 immersion, although it appears that immersion is more likely to have an impact on the WM (see also Pliatsikas et al., 2015). The effects of bi-/multilingualism on the GM are further demonstrated in a structural MRI study by Kaiser et al. (2015). In this study, possibly the first of its kind on multilinguals, it is suggested that successive L2 learning leads to more extended changes in GM compared to early simultaneous language learning. This effect persists even in individuals that learn a third language later in life, suggesting that early immersive bilingualism might lead to more effective synaptic connectivity for language learning, which in turn leads to less profound structural changes during late learning of additional languages.

Taken together, the papers in this E-book demonstrate the role and the importance of experienced-based factors, and especially linguistic immersion, for the acquisition and processing of a second or a third language. We hope that this E-book will inspire researchers to pay particular attention to the environmental factors that shape the linguistic experiences of their non-native participants, and to present comprehensive descriptions of their groups' linguistic background, including detailed information about their bi-/multilingual immersion.

## References

speech in noise. Front. Psychol. 5:449. doi: 10.3389/fpsyg.2014. 01449

**Conflict of Interest Statement:** The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Copyright © 2015 Pliatsikas and Chondrogianni. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

## Phonological and orthographic cues enhance the processing of inflectional morphology. ERP evidence from L1 and L2 French

## *Haydee Carrasco-Ortiz 1 and Cheryl Frenck-Mestre2,3 \**

1 Universidad Autónoma de Querétaro, Santiago de Querétaro, Mexico

2 Laboratoire Parole et Langage, Centre National de Recherche Scientifique, Aix-en-Provence, France

3 Aix-Marseille Université, Aix-en-Provence, France

#### *Edited by:*

Christos Pliatsikas, University of Kent, UK

#### *Reviewed by:*

Joana Acha, Basque Centre on Cognition, Brain and Language, Spain Phaedra Royle, Université de Montréal, Canada

#### *\*Correspondence:*

Cheryl Frenck-Mestre, Laboratoire Parole et Langage, Centre National de Recherche Scientifique, 5 rue Pasteur, Aix-en-Provence, France e-mail: cheryl.frenck-mestre@ univ-amu.fr

We report the results of two event-related potential (ERP) experiments in which Spanish learners of French and native French controls show graded sensitivity to verbal inflectional errors as a function of the presence of orthographic and/or phonological cues when reading silently in French. In both experiments, verbal agreement was manipulated in sentential context such that subject verb agreement was either correct, ill-formed and orally realized, involving both orthographic and phonological cues, or ill-formed and silent which involved only orthographic cues.The results of both experiments revealed more robust ERP responses to orally realized than to silent inflectional errors.This was true for L2 learners as well as native controls, although the effect in the learner group was reduced in comparison to the native group. In addition, the combined influence of phonological and orthographic cues led to the largest differences between syntactic/phonological conditions. Overall, the results suggest that the presence of phonological cues may enhance L2 readers' sensitivity to morphology but that such may appear in L2 processing only when sufficient proficiency is attained. Moreover, both orthographic and phonological cues are used when available.

**Keywords: ERPs, verbal inflection, late bilinguals, phonological processing, sentence processing**

## **INTRODUCTION**

Can one reed a book? Indeed, whether or not one necessarily activates phonological representations when reading and accessing the meaning of a word is a long standing debate in reading research (McCusker et al., 1981; Morris and Folk, 2000; Harm and Seidenberg, 2004). Early theories assumed that phonological recoding was a secondary, slower, route to meaning as compared to "direct access" via orthographic codes alone (Paap and Noel, 1991). This view has been seriously challenged in the last 15 years. Today's debate lies not in the question of whether phonological information is retrieved but how and when, i.e., whether phonological information is retrieved pre-lexically or only once a stored lexical form has been activated on the basis of orthography, thus giving rise to stored phonological information (for recent reviews seeVan Orden and Kloos, 2005; Hino et al., 2013).

The strongest evidence for phonological mediation during the processing of written words has been provided by research on single-word reading (Van Orden, 1987; Lukatela and Turvey, 1993; Jared et al., 1999). Seminal behavioral work in this area has shown that the activation of phonological information is both rapid and automatic, while perhaps lagging one beat behind that of orthography (Perfetti and Bell, 1991; Ferrand and Grainger, 1993). Said findings have since been replicated using event-related potentials (ERPs; Grainger et al., 2006).

Less attention has been paid to the role of phonological information during sentence processing; however, those studies that have examined this question have shown benefits. In both English and in French, a "preview" of the phonological information contained in the upcoming word in the sentence facilitates the reading of said word (Pollatsek et al., 1992; Rayner et al., 1995, 1998; Miellet and Sparrow, 2004; Ashby et al., 2006; but see Daneman and Reingold, 2000). The effect is not restricted to alphabetic languages; it has also been reported for logographic languages, such as Chinese (Pollatsek et al., 2000; Liu et al., 2002; Tsai et al., 2004), The finding that the prior activation of phonological information enhances reading performance, whichever the language under question, adds considerable weight to the hypothesis that such is part and parcel of the natural reading process (although see Van Orden and Kloos, 2005; Hino et al., 2013 for further discussions of these phonological effects).

The present study examined the question of phonological recoding, but from a syntactic viewpoint. We examined the impact of phonological cues on the processing of subject–verb agreement in sentential context. Moreover, we examined this question in both first (L1) and second language (L2) processing. Indeed, this issue is important not only for understanding the contribution of phonology to morphological processing in native readers but also in understanding whether phonology can be useful in learning verbal inflection in an L2. The language under question was French, which presents a particularly interesting case to study how phonological representations may influence how the orthographic code is processed.

Processing written French requires dealing with numerous morphological inflections that do not have overt phonological representations. Regular inflections of the present tense are an

illustrative example of this phonetic opacity. Morphological variations are not systematically represented in the phonological code; verbal inflections of the three singular persons for regular (first group) verbs are phonologically identical, despite the orthographic variation for the second singular person [e.g. *tu parles* "you speak" is pronounced the same as *je/il parle* "I/he eat(s)"]. Analogously, the third person plural inflected form is phonologically identical to that of the three singular persons regardless of orthographic variation across forms [e.g. *ils parlent* "they speak" is pronounced the same as *je/tu/il parle(s)* "I/you/he speak(s)"]. The absence of audible distinctions for different morphological forms in written French seems to account for the majority of errors made in verbal agreement production (Brissaud and Sandon, 1999; Negro and Chanquoy, 2000; Largy and Fayol, 2001; Chevrot et al., 2003). These studies have indeed shown that the presence of an audible morphological marker considerably reduces verbal agreement errors in children and skilled literate adults alike. Akin to the results obtained for the French language, both Dutch children and experienced adults produce more spelling errors on regularly inflected verb forms that do not include audible differences than for those that do (Frisson and Sandra, 2002; Sandra et al., 2004).

The effect of phonological mediation on inflected morphology can also be seen in comprehension, although debate indeed remains as to the systematic nature of this effect. In a self paced reading study, Brysbaert et al. (2000) examined whether orthographic information is necessary and/or sufficient to process homophonous verb forms and how the reading system deals with this type of silent morphological information. To do so, they looked at the respective contribution of orthographic and phonological cues on the processing of verbal tense in short sentence contexts. Results for native Dutch readers showed that orthographic cues alone sufficed to process the tense of the verb. These results were interpreted as evidence that the reading system is sensitive to orthographic information that is not represented at the phonological level. However, according to the authors, these findings could not be taken as evidence against the use of phonological cues in normal reading. Indeed, the simple presence of homophonic verb forms may have triggered the alternative use of orthographic information in order to disambiguate the verb. In line with the model forwarded by Harm and Seidenberg (2004), numerous empirical studies have shown that orthographic and phonological information can be activated in parallel during silent reading (cf. Van Orden and Kloos, 2005, for a review).

Studies that used ERPs to investigate the processing of inflectional morphology during written sentence processing have provided further understanding about the role of phonological cues in this process, in both native and non-native speakers (Osterhout et al., 2004, 2006; Frenck-Mestre et al., 2008). In a longitudinal study, Osterhout et al. (2004) suggested that L2 learners can quickly integrate morphosyntactic features with minimal instruction (e.g. 4 months), especially when features are present in the native language and morphological inflections involve phonological markers. Results showed that English L1– French L2 learners elicited an ERP effect in response to verbal agreement violations that presented phonological cues [e.g. *Tu*

*adores\*∗*adorez* "You adore(s)"], whereas no variation in the ERP responses was observed in response to determiner-noun agreement errors, which were both largely absent from the native grammar and that involved silent morphemes [e.g. *Tu manges des hamburgers\*∗*hamburger* "You eat hamburger(s)"]. However, it remained unclear whether it was the similarity of grammatical features across L1–L2 alone, or this factor combined with the oral realization of morphemes that lead to faster learning and a more systematic brain response to violations.

To isolate the effects of phonological realization on morphosyntactic processing, subsequent studies manipulated the presence versus the absence of phonological cues to grammatical morphemes for shared grammatical features in L1 and L2 (Frenck-Mestre et al., 2008; McLaughlin et al., 2010). Frenck-Mestre et al. (2008) examined the impact of phonological realization on verbal agreement in both native and non-native speakers of French. Results showed that compared to grammatically correct sentences, verbal agreement errors involving orally realized morphemes elicited a P600 effect for both native French speakers and German L1–French L2 learners. In contrast, silent inflectional errors produced different ERP patterns across the two groups. French native speakers showed a smaller P600 effect in comparison to orally realized errors whereas for L2 learners no robust effects were found in response to silent errors. These authors concluded that the presence of phonological information facilitates the processing of verbal agreement errors in native speakers and enhances the learning rate of verbal inflection in L2 learners of French.

The effects of phonological realization on morphosyntactic learning were also examined longitudinally in non-native speakers by McLaughlin et al. (2010). ERPs were recorded in three consecutive sessions while English L1–French L2 learners read the same materials as those used by Frenck-Mestre et al. (2008). At the end of the third session, a subgroup of learners presented an N400 effect to verbal agreement violations. By contrast, the other subgroup of learners, who first elicited an N400 response to inflectional errors, showed a subsequent small P600 effect in this third session. Although ERP differences were not observed as a function of whether the inflectional errors were phonologically realized or silent, learners' acceptability judgments were indeed sensitive to the presence of phonological cues. According to the authors, the processing of orthographic cues may not have triggered the activation of phonological information in L2 learners in contrast to the results found for native speakers and more proficient learners (Frenck-Mestre et al., 2008). However, the presence of oral cues does nonetheless seem to have an effect on morphological learning in the early stages of acquisition as evidenced by the learners' behavioral responses.

The current set of studies further investigated the extent to which phonological cues impact upon the processing of inflectional morphology in silent reading. Thus far, behavioral and ERP studies have presented inconsistent results with respect to the specific contribution of phonological cues during morphosyntactic processing in both native and non-native language readers (Brysbaert et al., 2000; Frenck-Mestre et al., 2008; McLaughlin et al., 2010). Indeed, different levels of sensitivity to phonological cues have been suggested in the literature discussed above. Thus, in two experiments, we aimed to determine the extent to which native and non-native readers are sensitive to the presence of phonological cues when processing inflectional morphology. To do so, we recorded ERPs from native French speakers as well as from Spanish L1–French L2 learners while they read sentences that contained subject–verb agreement errors which were either phonologically realized, i.e., when morphological information involved both orthographic and phonological cues, or silent, i.e., when morphological information involved orthographic cues that were not orally realized (cf. **Table 1**).

In a first experiment, we wished to determine whether the absence of an effect of phonological cues to verbal morphology in L2 learners reported by McLaughlin et al. (2010) was indeed attributable to the relatively low proficiency of these learners. If phonological recoding only comes into play at a more advanced level of L2 proficiency, we should find that more proficient L2 learners show the effect. To address this question, we examined L1 Spanish speakers who were immersed in the French language and who had several years of formal instruction in this language. Based on the findings reported by Frenck-Mestre et al. (2008), we predicted that these more advanced learners would show sensitivity both online and offline to verbal inflected violations and that such would vary as a function of the presence of phonological cues.

In a second experiment, we examined whether the presence of orthographic cues in addition to phonological ones may enhance processing of inflectional morphology. Brysbaert et al. (2000) found that the added presence of phonological cues did not allow participants to recover the tense of verbs faster, as compared to both orthographically and phonologically ambiguous forms. They concluded that readers can process verbal inflection as easily when silent as when orally realized. To address this issue, in our second experiment we manipulated verbal inflections such that orthographic variation was held constant across varying phonological conditions. Both a new control group of native French speakers and a new group of advanced Spanish–French bilinguals were tested.

The two groups of Spanish–French late bilinguals recruited for the present study were considerably more advanced than the English–French late L2 learners who participated in the McLaughlin et al. (2010) study. Importantly, all of our L2 participants were enrolled in university level classes conducted in French at a French university and had been immersed in the French language for

roughly 6 months at the time of the study. There is clear evidence that direct classroom instruction on phonological form can improve learning rate of French grammar (Arteaga et al., 2003). Nonetheless, as highlighted by Muñoz (2008, 2014), we can assume in line with the data from numerous linguistic and psycholinguistic studies that immersion will exert an important influence on L2 proficiency. As concerns the ability to compute syntactic structures, late L2 learners who have been immersed in the L2 for several years show a preference for resolving ambiguous structures in a manner similar to native speakers, quite unlike less experienced L2 learners who show an influence of their L1 (Frenck-Mestre, 2002; see also Dussias, 2003). It is important to underline that such a result is not a product of any explicit training but simply the by-product of extended experience with the L2 in daily life. More recently, Pliatsikas and Marinis (2013) reported successful online, immediate processing of complex syntactic structures (filler-gap dependencies) in a group of L2 English speakers who had been immersed for several years in their L2 environment but not for L2 learners with less exposure. Again, no specific training on said structures was given; with more years of experience, the late L2 learners simply achieve a high level of automatized syntactic parsing. Note, these findings are at odds with the claim that late L2 learners make do with shallow parsing based on heuristics (Clahsen and Felser, 2006), but argue in favor of models which assume that provided sufficient experience with/exposure to a language adult learners will achieve "nativelike" syntactic parsing (Herschensohn, 2000; Hopp, 2010; Steinhauer, 2014).

There is also some electrophysiological evidence that adult learners benefit from "naturalistic" or implicit learning as opposed to explicit instruction when confronted with a new language. Morgan-Short et al. (2012) reported that adult learners who were given implicit instruction on an artificial grammar, somewhat akin to what happens in immersion, showed "more native like" cortical responses to violations of word order than did a group of learners with equal exposure but explicit instruction. The pattern of ERP results was nonetheless complex. Participants were tested twice, once when at a low level of proficiency in the artificial language and again, following more training when they had achieved a high level of proficiency. Morgan-Short et al. (2012) reported that at higher proficiency, the implicit learning group showed a "native-like" pattern, consisting of an anterior-negativity followed by a P600 response to word order violations, whereas the

**Table 1 | Examples of the three sentence conditions (correct, incorrect and phonologically realized, incorrect and silent) for the six different verbal persons in French.**

explicit learning group showed only a P600. First, as noted by many and recently reiterated by Steinhauer (2014) and Tanner (2014), the presence of an early negativity (whether left lateralized or not) in response to syntactic processing difficulty is not systematic enough to be considered the hallmark of automatic syntactic parsing, whether in a native or late learned language (but see Molinaro et al., 2011). Perhaps more convincingly, at the lower level of proficiency the implicit learning group showed an N400 effect (albeit preceded by an early negativity, from 150 to 300 ms and extending to 700 ms), which then became a P600 (albeit preceded by the same early negativity – which may simply have been the remnant of the N400) at the second testing period. The explicit training group showed no ERP response when at a low level of proficiency. Hence, if nothing else, the implicit learning elicited a cortical response earlier than did explicit training. It is of interest that this is the first study, to our knowledge, to show an "N400–P600" transition for aurally presented sentences, and for artificial grammars.

In both experiments, we expected the cortical response to grammatical violations to vary as a function of the presence of overt phonetic cues to grammatical morphemes. Exactly what ERP signature we could expect to show variation depends upon the particular study that one considers. In Frenck-Mestre et al. (2008) variation in the P600 response was found in both native and L2 speakers but of different types; in native speakers, orally realized inflectional errors produced a larger P600 response than silent errors. In L2 speakers, orally realized errors elicited a significant P600 response while silent errors produced only a hint of variation and in the N400 response. Seminal work by Osterhout et al. (2004) has shown that adult L2 learners can show either the more typical P600 response or an N400 effect when confronted with violations of inflectional morphology, and that some L2 learners show a gradual shift from an N400 effect to a more typical P600 response as a function of grammatical competence. This result has since been replicated, both in late L2 learners (McLaughlin et al., 2010; Tanner et al., 2013) and in "heritage" L2 speakers, i.e., speakers whose parents are native speakers but who were raised and schooled in an environment where the ambient language was not that of their parents (Tanner et al., 2013). Other L2 studies have also reported N400 effects in response to grammatical violations, but as a function of grammatical structure rather than competence, with the same L2 speakers showing either an N400 or a P600 depending upon the familiarity with/frequency of structures in the L2 (Foucart and Frenck-Mestre, 2012). It is of importance to note that an N400 effect to syntactic violations is not specific to L2 processing. Osterhout (1997) clearly demonstrated that native speakers can show an N400 effect rather than a P600 in response to violations of syntactic expectancies, especially if the critical word is sentence final. This result, although often swept under the rug in L1 studies of syntactic processing where a P600 dominates in the averaged waveform, especially if the critical word is sentence medial, is well known to any who have looked at their individual data (see also Osterhout et al., 2004). This issue has recently been revisited by Tanner and Van Hell (2014). It has also been shown that the magnitude of the P600 response in native speakers is highly linked to their linguistic proficiency (Pakulak and Neville, 2010). Given all of the above, it is plausible to assume that we might

find variation in either of these components as a function of the well formedness of our sentence materials and the overt phonological realization thereof. The debate about what these cortical signatures reveal about sentential processing will be presented in the general discussion and in light of the results obtained here (for discussions, see Steinhauer et al., 2009; Molinaro et al., 2011; Tanner, 2014).

## **EXPERIMENT 1**

The goal of Experiment 1 was to examine the extent to which advanced Spanish L1–French L2 learners rely on phonological cues to process inflectional morphology online. In this aim, we examined the ERP responses of participants while they read sentences that contained either phonologically realized or silent subject–verb agreement errors. If phonological cues are indeed available online to advanced L2 learners, we should replicate previous results (Frenck-Mestre et al., 2008) showing that these cues increase L2 readers' sensitivity to morphological violations in like fashion to native controls. If phonological cues are not, however, taken into account as systematically during online L2 processing we can predict offline differences for silent and orally realized errors but not variations in the ERP response for the L2 group. Indeed, the question remains open whether the lack of an online effect of phonological cues in the L2 reported by McLaughlin et al. (2010) is attributable to the lower proficiency of the L2 learners as compared to those studied by Frenck-Mestre et al. (2008) or to a generally less systematic use of these cues during L2 processing. To ascertain whether the pattern for our late Spanish–French bilinguals was similar to that previously reported for native French speakers, we report data for a control group, which largely overlapped with that reported in Frenck-Mestre et al. (2008).

## **METHOD**

### *Participants*

Sixteen native Spanish speakers (eight female) aged 21–29 years (mean age 24.2 years) participated in the study (one was excluded from analyses due to excessive artifacts). All were classifiable as "late bilinguals" (mean age of acquisition of French, 16.8 years, and mean years of study of French, 4.7 years). All had passed the second level of the DELF, a standardized test of French as a second language, were following a university curriculum in the French language and were living in France (mean of 5.5 months) at the time of participation. Their mean self-rating of reading expertise in the French language (on a scale from 1 to 6) was 4.0 (SD = 0.9). Another group of 15 participants were native French speakers (seven female) aged 20–24 years (mean age 21.5 years), enrolled at a French university (one participant was replaced due to excessive movement during ERP recording; 13 of these participants were the same as reported in Frenck-Mestre et al., 2008). All participants – French and Spanish – had also learned English as a second language throughout secondary school, although their fluency in this language was not tested. All participants were dominant right handed with normal or corrected-to-normal vision. Participants were paid for their participation. They all signed an informed consent form for the study, which was approved by the French

ethics committee, and were fully debriefed at the end of the experiment.

## *Materials*

Critical stimuli were twenty regular French verbs of the first group presented in 90 declarative present-tense sentences. Grammaticality of sentences was manipulated by verbal agreement between the subject pronoun and the verb. All six verbal persons were used. Three morphosyntactic conditions were created by manipulating the pairing of verbal person and verbal inflection, with 30 sentences per condition: correct (e.g. "je parle" ), incorrect and orally realized (e.g. "je parlez" ), and incorrect and silent (e.g. "je parles" ). Examples are provided in **Table 1**. In the correct and phonologically realized incorrect conditions, the three singular verbal persons were seen an equal number of times (four times each) as were the 3 plural verbal persons (six times each), In the phonologically silent incorrect condition, the first person plural ("nous") and second person singular formal/plural ("vous") were not included as any mis-pairing gives rise to an overt phonological form; the other four forms (1st, 2nd informal and 3rd singular, 3rd plural) were seen equally. Sentences were from 5 to 10 words in length and critical verbs appeared at varying word positions, from the second to the fifth word, but never in the final position. Each verb was presented either four or five times across the 90 sentences. Forty-five additional filler sentences that did not involve morphosyntactic anomalies were included as filler sentences to distract participants' attention from the morphosyntactic manipulation. This fillers also included correct verbal inflections of the different verbal persons in such a way that all verbal persons were seen an equal number of times in correct and incorrect conditions across the entire set of materials. A latin square design was used, such that each experimental sentence was rotated across three lists, with each occurring only once per list and in a different condition per list. Each list contained 90 experimental sentences (30 per condition) and 45 filler sentences. Each participant saw only one list and three different random orders of presentation of sentences were created per list.

## *Procedure*

Participants were instructed to read sentences silently from a computer monitor while seated comfortably in an isolated room. Each trial sequence consisted of the following: a fixation cross (500 ms) followed by the stimulus sentence, which was presented visually one word at a time, each word being displayed for 450 ms followed by a 150 ms blank-screen inter-stimulus interval, followed by a "oui/non" prompt. Participants read for comprehension and made meaning-acceptability judgments at the prompt after each sentence by means of a button box.

EEG activity was recorded continuously from 21 scalp locations referenced to the left mastoid, with a sampling rate of 200 Hz. Two additional electrodes were used to monitor for horizontal and vertical eye movements. Epochs began 100 ms prior to stimulus onset and continued 1100 ms thereafter. Average ERPs were calculated off-line from trials free of artifacts (less than 3% of rejections per condition overall; no differences in rejection rate were found as a function of condition or participant

group). Averaging was performed without regard to behavioral responses1.

## *Data analysis*

Mean voltage amplitudes and peak latencies were calculated for two time windows: 400–550 and 600–800 ms. These time epochs have been associated with the N400 and/or anterior negativities and P600 components, respectively. Data acquired at midline and lateral sites were treated separately. A three-way ANOVA was performed on the mean amplitude and peak latency acquired at midline, with two levels of Group (Native French vs. Spanish– French bilinguals), and repeated measures on three levels of Verbal inflection (correct inflection, orally realized and silent inflectional errors) and Electrode (frontal, central, and parietal). Five-way ANOVAs were performed on the data acquired at lateral sites, involving Group (Native French vs. Spanish–French bilinguals), and repeated measures on three levels of Verbal inflection (correct inflection, orally realized and silent inflectional errors), two levels of Hemisphere (left, right), two levels of Site (anterior, central– parietal) and three levels of Electrode (three anterior and three central–parietal per hemisphere). The Greenhouse and Geisser (1959) correction was applied to all repeated measures with greater than one degree of freedom. All significant differences involving more than two conditions were confirmed by *post hoc* comparisons (Bonferroni).

### **RESULTS**

### *Behavioral data*

Grammatical acceptability judgments were analyzed as a function of Group (native French vs. Spanish L1–French L2 learners) and Verbal inflection (correct, orally realized, and silent errors). There was a main effect of Verbal inflection [*F*(2,56) = 11.52, *p* < 0.01] that tended to be modified by Group [*F*(2,56) = 3.42, *p* < 0.06]. *Post hoc* comparisons revealed the main effect of Verbal inflection to be due to the difference in correct responses for silent errors compared to orally realized errors and correct inflections (*p* < 0.01). This effect was further confirmed in each group independently [French (*F*(2,28) = 10.23, *p* < 0.01) and Spanish L1–French L2 learners (*F*(2,28) = 3.39, *p* < 0.05]. Thus, the difference in the percentage of correct responses for silent errors compared to orally realized errors and correct inflections was bigger in the native French speakers in comparison to that observed in Spanish L1–French L2 learners [mean percentage of correct detections for correct sentences, orally realized and silent errors were for native French speakers 93% (SD 3.1), 96% (SD 2.9), and 72% (SD 8.1), respectively, and for Spanish L1–French L2 learners 91% (SD 3.4), 89% (SD 5.6), and 82% (6.1), respectively].

1In both experiments, ERP data were analyzed based on all trials that were not contaminated by artifact. Response-contingent analyses are problematic in the present study given the unequal number of trials across experimental conditions. Indeed, in the phonologically silent condition, there was a substantial percentage of trials on which participants, whether native or L2 speakers, failed to consciously report an error, which was not the case for sentences in the orally realized condition. We nonetheless looked at the ERP data based on response-contingency. The results reported herein held up for all comparisons between orally realized inflectional errors and correct inflections. The results for the silent inflectional errors were less robust. Nonetheless, since excluding those trials in which the behavioral response was incorrect led to excluding more than 40% of the data, the reliability of these analyses is questionable.

#### *Event-related potentials*

Grand-average waveforms to the critical verbs for each verbal agreement condition are shown in **Figure 1** for native French and in **Figure 2** for Spanish L1–French L2 participants. As is visible in the figures, a clear "N1–P2" complex was evoked in the first 300 ms following critical word onset, for all conditions. Following this, in comparison to correctly inflected verbs, inflectional errors provoked a positive deflection that began at roughly 500 ms and persisted until around 800 ms, with a peak at roughly 600 ms, generally described as a P600 effect.

This was true for both orally realized and silent errors and was observed for both native French speakers and for Spanish–French late bilinguals. In addition, a larger P600 effect was apparent for the orally realized errors compared to silent errors in both participant groups. Statistical comparisons confirmed these differences.

## *100–300 ms epoch*

Statistical analyses revealed no reliable differences across conditions in the first 300 ms following critical verb onset.

**FIGURE 1 | Grand mean averages for native French speakers as a function of verbal inflection condition and electrode site.**

#### *400–600 ms epoch*

Analysis of data in this time window revealed no effects at midline. For lateral electrodes, an effect emerged for participant Group [*F*(1,28) = 5.26, *p* < 0.02] which was modified by interactions with Hemisphere × Verbal inflection [*F*(2,56) = 3.08, *p* < 0.05]. Independent analyses performed on the data for each participant group showed this interaction to be due to the presence of a positive deflection in response to both orally realized and silent errors only for Spanish L1–French L2 learners. No such early P600 effect was apparent in the native French group for whom no reliable differences as a function of experimental factors were found in this time window.

### *600–800 ms epoch*

Analysis of data in this time window yielded a main effect of Verbal inflection [midline: *F*(2,56) = 18.41, *p* < 0.0001; lateral sites *F*(2,56) = 9.67, *p* < 0.001]. At midline, compared to wellformed sentences both orally realized and silent inflectional errors produced a significant P600 effect (*p* < 0.01 or better for both cases), which was significantly larger for orally realized errors than silent errors as confirmed by Bonferroni *post hoc* comparisons (*p* <0.01). In addition, there was a trend for the interaction involving Verb, Group, and Electrode site [*F*(4,112) = 2.29, *p* < 0.10]. At lateral sites, there was a significant interaction between Verb, Group, and Hemisphere [*F*(2,56) = 3.83, *p* < 0.03]. Given such, independent analyses were performed on the data in this time window for each of the two participant groups.

In the native French group, an effect of Verbal inflection was observed at midline [*F*(2,28) = 7.11, *p* < 0.003] which was modified by Electrode [*F*(4,56) = 8.44, *p* < 0.001]. *Post hoc* comparisons revealed that compared to grammatically correct cases, orally realized errors elicited a significant P600 response at all three midline electrodes (*p* < 0.01 or better) whereas silent errors produced a reliable P600 response at central (*p* < 0.001) and parietal (*p* < 0.001) but not at frontal sites. In addition, orally realized errors produced a significantly larger P600 effect than silent errors at central (*p* < 0.03) and parietal sites (*p* < 0.001). The effect of Verbal inflection was also significant at lateral sites [*F*(2,28) = 3.91], revealing a significant P600 effect for both orally realized and silent errors. The P600 effect was present over central–parietal but not over anterior sites and it varied as a function of Verbal inflection [*F*(2,28) = 8.57, *p* < 0.004]. *Post hoc* comparisons revealed no P600 effect at anterior lateral sites, whereas at central–parietal lateral sites both types of error produced a robust P600 effect. In addition, this P600 effect was larger for orally realized errors (*p* < 0.0001) than for silent errors (*p* < 0.001), although the direct comparison of the two error conditions at posterior lateral sites did not show a reliable difference.

In the Spanish L1–French L2 learners group, a significant effect of Verbal inflection was observed at midline [*F*(2,28) = 13.8, *p* < 0.0001], which did not interact with Electrode. *Post hoc* comparisons at midline sites confirmed that compared to control sentences, orally realized and silent inflectional errors both produced a P600 effect (*p* < 0.01 or better) and differed from each other at all three midline sites (*p* < 0.05). At lateral sites, there was also an effect of Verbal inflection [*F*(2,28) = 7.87, *p* < 0.01], which

tended to be modified by Hemisphere [*F*(2,28) = 3.37, *p* < 0.06] and was significantly so by the interaction involving Verbal inflection, Site (anterior/posterior), and Electrode [*F*(4,56) = 10.45, *p* < 0.001]. At anterior lateral sites, *post hoc* comparisons revealed that orally realized errors produced a more widespread P600 effect over the left than right hemispheres whereas the effect for silent errors was only significant over the right hemisphere (*p* < 0.03). At posterior lateral sites, an effect of Verbal inflection was observed [*F*(2,28) = 10.83, *p* < 0.01], with orally realized errors producing a robust widespread P600 effect (*p* < 0.001) and silent errors producing a more reduced effect (*p* < 0.05) that was also significantly smaller than that produced by orally realized errors over some electrodes (*p* < 0.002).

### **DISCUSSION**

The results of Experiment 1 clearly demonstrate online sensitivity to morphosyntactic violations for Spanish L1–French L2 learners, in like manner to native French speakers, as revealed by a P600 response to these violations. Of principal interest in the present study was whether phonological cues would enhance the processing of morphosyntactic violations during silent reading. For native speakers, orally realized errors produced a greater P600 effect than silent errors, thus confirming previous results (Frenck-Mestre et al., 2008). In the same way, Spanish L1– French L2 learners showed a graded sensitivity to verbal inflection violations as a function of the presence of phonological cues. Indeed, the P600 response to orally realized errors was significantly larger than that observed to silent errors. The differentiated ERP response in non-native speakers contrasts nonetheless with recent work by McLaughlin et al. (2010). Using the same materials as in the present study but with less advanced English learners of French, these authors reported differences in sensitivity to verbal person violations as a function of whether these violations were orally realized or silent, but only on grammaticality judgments, not in the ERP response to these violations as reported here. In line with McLaughlin et al. and in view of our own results, we can forward the hypothesis that in less advanced L2 learners online processing may not be rapid and/or systematic enough to show a robust effect of phonological realization during reading in the ERP trace. We will re-examine this question in the general discussion in light of the results of Experiment 2.

To further investigate the role of phonology during silent reading and how such may impact grammatical processing as a function of L2 experience, we conducted a second experiment in which we again manipulated phonological variation. In line with interactive models of phonology and orthography during reading (Harm and Seidenberg, 2004) it is plausible that readers benefited from all cues available to them, whether phonological or orthographic. It is possible that the inclusion of plural pronouns in our first experiment may have enhanced the effect of oral realization that we observed, due to differences in orthography. Indeed, for the three singular pronouns the orthographic overlap between correct inflections and both the orally realized and silent violations was identical (one letter different in each case). Such was not the case for the plural, for which silent errors had more letters in common with correct inflections than orally realized errors did (for a more indepth discussion, see Frenck-Mestre et al., 2010). To address this question and to ascertain that the differences in processing we observed were indeed due to the oral realization of morphology, we conducted a further experiment in which orthographic cues were reduced. This was done by restricting the verbal person manipulation to the three singular pronouns (1st, 2nd, and 3rd person). In said case, it is possible to hold orthographic variations constant meanwhile varying phonological overlap.

## **EXPERIMENT 2**

In Experiment 1, we manipulated the presence vs. absence of oral cues to verbal agreement by mispairing inflection for both singular and plural pronouns. Our results clearly revealed an effect of phonological realization on agreement processing for both participant groups. The goal of Experiment 2 was to determine whether the effect of phonological realization observed in Experiment 1 was principally driven by phonological rather than orthographic cues. If so, we would expect this effect to persist when the amount of orthographic mismatch was identical across incorrect agreement conditions. Therefore, we used the three singular pronouns ("je," "tu," "il/elle"), for which verbal inflections vary by one letter and mispairing inflections may result in either orally realized or silent errors (see **Table 2**). We can predict that the presence of oral cues should enhance the reader's capacity to detect these errors. Based on previous ERP studies of written materials, we expected a variation in the amplitude of P600 and/or early negativities to verbal agreement errors as a function of oral cues, for native French and Spanish L1–French L2 speakers. It is also possible that an N400 effect could be elicited by morphological mispairings, especially in the L2 group. Indeed, various studies of adult L2 learners have reported N400 effects to just such errors, although none have manipulated the presence of overt oral cues to morphological variation (McLaughlin et al., 2010; Foucart and Frenck-Mestre, 2012; Morgan-Short et al., 2012; Tanner et al., 2013, 2014). The group of Spanish–French learners was, akin to the group tested in Experiment 1, immersed in French at the time of testing. All L2 participants had also had several years of formal study of the French language. As such, this group was comparable to that tested in the first experiment and considerably more advanced than the L2 learners tested by McLaughlin et al. (2010). Again, if L2 proficiency, as determined by either formal learning or amount of exposure is crucial to using phonological cues during reading in general and syntactic processing in particular, then we can predict similar results as found in Experiment 1, provided

that the phonological cues are sufficient to produce effects in the absence of additional orthographic cues.

## **METHOD**

## *Participants*

Fifteen native French speakers (eight female) aged 18–25 years (mean age 20 years) and 15 native Spanish speakers (nine female) aged 21–29 (mean age 26.8 years) participated in this study. None of the participants had taken part in the first experiment. All subjects were dominant right handed with normal or corrected-tonormal vision. They were paid for their participation and signed an informed consent form for the study, which was approved by the French ethics committee. They were fully debriefed at the end of the experiment. Spanish speakers were classifiable as "late bilinguals" (mean age of acquisition of French, 23.6 years, and mean years of study of French, 3.5 years). All had passed the second level of the DELF, a standardized test of French as a second language, were following a university curriculum in the French language and were living in France (mean of 6 months) at the time of participation. Their mean self-rating of reading expertise in the French language (on a scale from 1 to 6) was 4.2 (SD = 0.77). All participants – French and Spanish – had also learned English as a second language throughout secondary school, although their fluency in this language was not tested.

### *Materials*

An entirely new set of sentences was created for the purpose of this experiment. Critical stimuli were 30 regular French verbs from the first group (20 taken from Experiment 1) which were presented in 90 declarative present-tense sentences. Grammaticality of sentences was manipulated by verbal agreement between the subject pronoun and the verb. As in Experiment 1, 3 morphosyntactic conditions were created by manipulating the pairing of verbal person and verbal inflection, with 30 sentences per condition: correct (e.g. "je regarde"), incorrect and orally realized (e.g. "je regardez"), and incorrect and silent (e.g. "je regardes"). In contrast to Experiment 1, only the 3 singular persons were included. Sentences were from 5 to 10 words in length and critical verbs appeared at varying word positions, from the second to the fifth word, but never in the final position. Three lists were created such that each experimental sentence was rotated across lists in a Latin square design, with each occurring only once per list and in a different condition per list. In each condition, the three singular pronouns were seen an equal number of times (10 per each, with five masculine and five feminine for the third person singular). Sixty additional filler sentences

**Table 2 | Examples of the three sentence conditions (correct, incorrect and orally realized, incorrect and silent) for the three singular verbal persons in French used in Experiment 2.**

that did not involve morphosyntactic anomalies were included to distract participants' attention from the syntactic manipulation. These fillers also provided a balance for correct and mispaired verbal inflections across the entire set of materials. Each participant saw only one list and three different random orders of presentation of sentences were created per list.

#### *Procedure*

The procedure was identical to that of Experiment 1.

#### *Data analysis*

This was identical to that of Experimental 1 with the exception that the time epoch associated with the N400 and/or anterior negativity was examined in the 300–500 ms time window, and that associated with the P600 component was shifted to the 500–700 ms and 700–900 time windows based on visual inspection of waveforms.

### **RESULTS**

#### *Behavioral data*

Behavioral responses were analyzed based on grammatical acceptability judgments. A repeated-measures ANOVA involving Group (Native French vs. Spanish–French bilinguals) as a between subjects factor andVerbal inflection (correct, silent, and orally realized errors) as a repeated measure revealed a main effect of Verbal inflection [*F*(1,43) = 27.42, *p* < 0.01] which did not interact with Group (*F* < 1). Orally realized errors were better detected than silent errors and this was true for both participant groups [mean percentage of correct detections for correct sentences, orally realized and silent errors were 94% (SD 2.3), 92% (SD 3.5), and 73% (SD 8.2) for native French speakers and 89% (SD 4.7), 86% (SD 6.4), and 61% (SD 15.9) for Spanish L1–French L2 learners, respectively]. Given the differences across conditions as concerns the detection of errors, ERPs were calculated independent of responses. Moreover, as shown by numerous studies, behavioral responses are not necessarily indicative of cortical sensitivity (McLaughlin et al., 2004; Foucart and Frenck-Mestre, 2012; but see Foucart and Frenck-Mestre, 2011).

## *Event-related potentials*

Grand-average ERPs elicited by critical verbs in the three verbal agreement conditions (correctly inflected verbs, orally realized, and silent errors) are shown in **Figure 3** for native French and in **Figure 4** for Spanish L1–French L2 learners. Visual inspection of these waveforms revealed a clear "N1–P2" complex evoked in the first 300 ms following critical word onset, for all conditions. After 300 ms, two effects emerged. First, a negative component was observed over the left and right hemispheres, beginning around 300 ms and persisting until 500 ms, for inflectional errors as compared to correct verbal agreement. This negativity was observed predominantly in the native French participant group and mainly for orally realized inflectional errors. Following this negativity, inflectional errors provoked a positive deflection in comparison to correctly inflected verbs. This positivity presented different onset latencies across participant groups. For native French speakers positivity began at approximately 500 ms and persisted until roughly 800 ms, whereas for Spanish L1–French L2 learners the positivity began at 700 ms and persisted beyond 800 ms. Thus the

P600 effect was delayed in L2 learners. ANOVAs performed on the mean amplitude data confirmed these effects.

### *300–500 ms epoch*

Statistical analyses in this time window yielded a significant Verbal inflection by Group interaction at both midline [*F*(2,56) = 3.79, *p* < 0.03] and lateral sites [*F*(2,56) = 3.70, *p* < 0.03]. Independent analyses were subsequently performed on the data for each participant group. For native French speakers, a main effect of Verbal inflection was observed only at lateral sites [*F*(2,28) = 4.06, *p* < 0.04]. Planned comparisons confirmed reliable differences between correctly inflected verbs and orally realized errors at lateral sites (*p* < 0.03) while no differences were observed between correctly inflected verbs and silent errors (*p* > 0.15). The comparison of orally realized and silent errors showed a reliable difference (*p* < 0.03). For Spanish L1–French L2 learners, the main effect of Verbal inflection approached significance only at midline [*F*(2,28) = 2.97, *p* < 0.08]. *Post hoc* comparisons revealed that silent inflectional errors were more negative compared to correctly inflected verbs (*p* < 0.02). No differences between orally realized errors and correctly inflected verbs or between the two error conditions were found in this time window for this group.

### *500–700 ms epoch*

Analyses of the data in this time window showed a significant interaction between Group and Verbal inflection at midline [*F*(2,56) = 4.36, *p* < 0.01], while at lateral sites Verbal inflection interacted with Group and Site [*F*(2,56) = 2.65, *p* < 0.03]. Separate analyses were subsequently performed on the data for each participant group. For native French speakers, a main effect of Verbal inflection was observed at midline [*F*(2,28) = 4.35, *p* < 0.02] and at lateral sites [*F*(2,28) = 4.06, *p* < 0.02]. *Post hoc* comparisons (Bonferroni) at midline showed that both orally realized and silent errors differed from correct sentences (*p* < 0.01), whereas orally realized and silent errors did not differ from each other. At lateral sites, the effect of Verbal inflection was modified by Site [*F*(2,28) = 4.15, *p* < 0.05]. Separate analyses at anterior and posterior sites revealed a main effect of Verbal inflection only at posterior sites [*F*(2,28) = 4.25, *p* < 0.03]. At posterior sites, *post hoc* comparisons confirmed reliable differences between correctly inflected verbs and orally realized errors (*p* < 0.03), while no differences were found between correctly inflected verbs and silent errors (*p* > 0.15). The direct comparison of the two error conditions showed a small trend (*p* < 0.11).

Analyses conducted on Spanish L1–French L2 speakers in this time window showed no effect of Verbal inflection or significant interactions at any electrode site (*F* < 1).

### *700–900 ms epoch*

Analyses of data in this time window yielded a significant interaction between Verbal inflection and Group at midline [*F*(2,56) = 6.27, *p* < 0.01] and at lateral sites [*F*(2,56) = 5.35, *p* < 0.01]. Separate ANOVAs were subsequently conducted on the data for each participant Group. Native French speakers showed no significant effects or interactions at any electrode site (*F* < 1). In contrast, Spanish L1–French L2 speakers revealed a significant effect of Verbal inflection at midline [*F*(2,28) = 5.93, *p* < 0.01]

**FIGURE 3 | Grand mean averages for native French speakers as a function of verbal inflection condition and electrode site.**

which was modified by Electrode site [*F*(4,56) = 3.73, *p* < 0.03]. At midline, *post hoc* comparisons revealed that compared to correct cases, orally realized errors elicited a significant P600 response at central (*p* < 0.02) and parietal (*p* < 0.001) sites, while no significant effect was observed at any electrode sites for silent errors, for any comparison. At lateral sites, a significant effect of Verbal inflection was observed [*F*(2,28) = 4.27, *p* < 0.02] which interacted with Site [*F*(2,28) =9.6, *p* <0.01]. *Post hoc* comparisons at anterior and posterior sites revealed that at posterior sites, orally realized but

not silent errors elicited a significant P600 (*p* < 0.01) in comparison to correct sentences, whereas at anterior sites no reliable P600 response was observed. Further, orally realized errors produced a significant P600 effect compared to silent errors (*p* < 0.01).

#### **DISCUSSION**

The goal of Experiment 2 was to confirm that the effect of phonological realization observed in Experiment 1 could be attributed to the additional presence of phonological cues rather than to orthographic cues alone. The results, obtained under conditions for which the amount of orthographic mismatch across verbal agreement conditions was controlled, showed again that orally realized verbal person violations provoked a reliable P600 response in comparison to correct cases and this was true for both native and non-native participants. In addition, compared to silent errors orally realized violations elicited a greater early negativity in native French speakers. Given its distribution, this effect can best be characterized as a member of the broad class of early negativities which has been reported in various studies (Rodriguez-Fornells et al., 2001; Hahne et al., 2006; Morgan-Short et al., 2012). In contrast to orally realized inflectional errors, silent errors elicited only a small effect. In the group of native French participants, silent errors only produced a significant P600 response at midline sites. For Spanish L1–French L2 speakers, the difference between orally realized and silent inflectional errors was clear and widespread; while orally realized errors elicited a P600, albeit in a late time window, silent errors did not produce any reliable effect in the ERP waveform.

## **GENERAL DISCUSSION**

The present set of studies showed that phonological cues enhance the processing of inflectional morphology when reading silently in either one's first or second language. Specifically, the processing of verbal inflectional errors produced a larger P600 effect when violations involved both orthographic and phonological cues relative to when only inaudible morphological cues are available. These results provide evidence of the contribution of phonology to morphological processing in both native and non-native readers. The general findings here are consistent with those of previous studies that show an impact of phonological cues on the processing of inflectional morphology in French (Frenck-Mestre et al., 2008, 2010; Carrasco and Frenck-Mestre, 2009; McLaughlin et al., 2010) and confirm a systematic benefit from the presence of phonological cues under conditions where orthographic overlap across experimental conditions was held constant (Experiment 2). Although this was true for both native French speakers and Spanish L1–French L2 speakers, distinct neural responses were observed for each group as a function of the presence vs. absence of phonological cues when processing morphosyntactic markers.

For native speakers, a bilateral early negativity was evoked in response to orally realized errors in comparison to correctly inflected verbs. This was found, however, only when minimal orthographic differences between correct and orally realized errors were present (i.e., only in Experiment 2). In contrast, silent errors did not elicit any significant negativity, under any conditions. Both in terms of timing and distribution, the anterior negativity observed for orally realized errors fall within the range of variations that have been reported in previous studies for syntactic violations (Rodriguez-Fornells et al., 2001; Hahne et al., 2006; cf. Molinaro et al., 2011 for a review). The nature of this early negativity has been associated with a fast and automatic syntactic analyzer involving an initial detection of the grammatical error (Friederici, 1995, 2002; Hahne and Friederici, 1999). In line with this assumption, the fact that this negativity was present for orally realized but not for silent errors would suggest that phonological information has an effect on the first morphosyntactic analysis allowing

a fast detection of orally realized inflectional errors. However, the interpretation of this early negativity should be considered with caution due to its lack of consistency across Experiments 1 and 2 and other previous studies (Frenck-Mestre et al., 2008, 2010; McLaughlin et al., 2010; Steinhauer, 2014; Tanner, 2014). Indeed, there is still considerable debate as to the significance and very nature of early negativities associated with syntactic processing in the monolingual literature (Osterhout, 1997; Molinaro et al., 2011; Tanner, 2014) which has seen repercussions in the literature on L2 processing (Frenck-Mestre, 2005; Steinhauer et al., 2009; Foucart and Frenck-Mestre, 2012; Steinhauer, 2014).

The results for native speakers showed that compared to orally realized errors, silent errors produced a smaller P600 effect in Experiment 1 and a reduced distribution in Experiment 2. The ERP differences observed for these two types of errors suggest that the presence of oral cues enhanced the syntactic analysis/reanalysis of violations of inflectional morphology in French. These results are in line with those obtained in previous off-line studies for native speakers of French (Negro and Chanquoy, 2000; Largy and Fayol, 2001) where phonologically realized morphemes induced fewer inflectional errors for verbal and nominal agreement in a written production task. It is noteworthy, nonetheless, that the difference observed between orally realized and silent inflectional errors was more pronounced in Experiment 1 in which the extent of orthographic differences between correctly inflected and erroneous cases was larger for orally realized than for silent errors. As such, the present results support the hypothesis that the added presence of orthographic cues indeed enhanced the effect of the oral realization of errors.

For the Spanish L1–French L2 speakers, no reliable early negativity was observed in response to verbal agreement errors. This result could fit, in a first instance, with the assumption that early negativities are restricted to native processing (Hahne, 2001) and or that they are associated with more advanced levels of processing (Steinhauer et al., 2009). However, the fact that various studies involving native speakers do not report any LAN effects in response to syntactic violations (Hagoort et al., 1993; Osterhout and Mobley, 1995; Osterhout et al., 2002; Frenck-Mestre et al., 2008; Foucart and Frenck-Mestre, 2011, 2012) renders difficult the interpretation of this absence of significant negativity effects in non-native speakers as a non "nativelike" processing. Indeed, the inconsistent presence of these LAN effects in native brain responses requires further research to reveal the underlying cognitive processes and the antecedent conditions that elicit or modulate it (Osterhout, 1997; Molinaro et al., 2011; Steinhauer, 2014; Tanner, 2014). Moreover, it has recently been suggested that individual differences in native speakers can account for the presence versus absence of early negativities to syntactic manipulations (Tanner, 2014). Clearly, further work is in order to clarify this issue.

In the present study, L2 learners showed a larger P600 effect when processing orally realized errors, as compared to silent errors and correctly inflected verbs. These results contrast with those reported in McLaughlin et al. (2010) where L2 learners showed no ERP difference between orally realized and silent errors. The greater on-line capacity to detect orally realized errors observed in the present study might be associated with the relative high language proficiency in our L2 learners. Increased second language processing might enable the activation of phonological information, which could have enhanced the L2 learner's capacity to detect morphological violations involving phonological cues. In addition, the results of Experiment 2 replicate those reported in Frenck-Mestre et al. (2008), showing an absence of an ERP response to silent errors for L2 learners. One interpretation for these results is that non-native participants in Experiment 2 were not systematically sensitive to morphological errors that are not overtly realized. It is, therefore, possible that the L2 participants' response to silent inflectional errors was not strong enough to elicit a visible ERP response in the second experiment in contrast to the results of Experiment 1. This inherent heterogeneity of response in the L2 participants may have contributed to the absence of an effect for silent inflectional errors. Indeed, behavioral data in Experiment 2 showed that orally realized errors were detected significantly better than silent errors.

As outlined above, the effect of the phonological realization of morphology differed across experiments. Indeed, the difference in the ERP response to orally realized and silent errors was larger and more widespread for both participant groups in Experiment 1 than in Experiment 2. One possible explanation is that more robust effects are observed for experimental conditions in which the number of orthographic cues present in verbal inflection errors is greater. In Experiment 1, orally realized errors included all six verbal persons producing, therefore, orthographically more salient errors compared to Experiment 2 in which only the three singular persons were used (e.g., "nous1st, plural parlent∗ 3rd, plural/parlons1st, plural" compared to ("je1st, sing parlez∗ 2nd, sing formal/plural/parle1st, sing"). This relative orthographic advantage may have improved the processing of verbal inflection errors in Experiment 1. This finding is in line with assumption that readers benefit from all linguistic input when processing language (Brysbaert et al., 2000; Harm and Seidenberg, 2004; Frenck-Mestre et al., 2010). Under a connectionist framework, a mutual dependence of orthographic and phonological codes operates in the computation of a written word (Harm and Seidenberg, 2004). Thus, the different contribution of orthographic and phonological codes across experiments may have impacted the processing of words.

An important issue for this paper was to confirm the contribution of phonological cues to the online processing of inflectional morphology. In line with Brysbaert et al. (2000), the results obtained in the present study suggest that orthographic cues that are not phonologically represented in inflectional morphology can still be processed, though perhaps in a more effortful way. Our results also suggest that the presence of phonological cues can enhance the processing of inflectional morphology, even under conditions for which the amount of orthographic mismatch was identical. Furthermore, the present study provides important evidence relative to both native and non-native speakers' use of these cues during silent reading.

Finally, the impact of phonological cues on morphological variations is not limited to verbal processing. Indeed, the processing of other morphological inflections such nominal gender concord has been found to be enhanced by the presence of phonological cues (Carrasco and Frenck-Mestre, 2009; Foucart and Frenck-Mestre, 2011, 2012; for a review see Frenck-Mestre et al., 2010). In addition, this effect of phonology has been observed in both native and non-native speakers with diverse language backgrounds. Thus, the current set of experiments points to an active use of phonological information when reading silently and such is true, moreover in both first and second language processing.

## **REFERENCES**

Arteaga, D., Herschensohn, J., and Gess, R. (2003). Focusing on phonology to teach morphological form in French. *Mod. Lang. J.* 87, 58–70. doi: 10.1111/1540- 4781.00178

perspective on spelling errors. *Brain Lang.* 81, 545–554. doi: 10.1006/brln. 2001.2546

**Conflict of Interest Statement:** The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

*Received: 04 June 2014; accepted: 25 July 2014; published online: 13 August 2014. Citation: Carrasco-Ortiz H and Frenck-Mestre C (2014) Phonological and orthographic cues enhance the processing of inflectional morphology. ERP evidence from L1 and L2 French. Front. Psychol. 5:888. doi: 10.3389/fpsyg.2014. 00888*

*This article was submitted to Language Sciences, a section of the journal Frontiers in Psychology.*

*Copyright © 2014 Carrasco-Ortiz and Frenck-Mestre. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.*

## An ERP study on L2 syntax processing: When do learners fail?

#### *Nienke Meulman1 \*, Laurie A. Stowe1, Simone A. Sprenger 1, Moniek Bresser 2 and Monika S. Schmid1,3*

1 Center for Language and Cognition, University of Groningen, Groningen, Netherlands

2 Research School of Behavioral and Cognitive Neurosciences, University of Groningen, Groningen, Netherlands

3 Department of Language and Linguistics, University of Essex, Colchester, UK

#### *Edited by:*

Christos Pliatsikas, University of Kent, UK

#### *Reviewed by:*

Christos Pliatsikas, University of Kent, UK Eleonora Rossi, Penn State University, USA

#### *\*Correspondence:*

Nienke Meulman, Center for Language and Cognition, University of Groningen, Oude Kijk in 't Jatstraat 26, PO Box 716, 9700 AS Groningen, Netherlands e-mail<EMAIL_ADDRESS>
Event-related brain potentials (ERPs) can reveal online processing differences between native speakers and second language (L2) learners during language comprehension. Using the P600 as a measure of native-likeness, we investigated processing of grammatical gender agreement in highly proficient immersed Romance L2 learners of Dutch. We demonstrate that these late learners consistently fail to show native-like sensitivity to gender violations. This appears to be due to a combination of differences from the gender marking in their L1 and the relatively opaque Dutch gender system. We find that L2 use predicts the effect magnitude of non-finite verb violations, a relatively regular and transparent construction, but not that of gender agreement violations. There were no effects of age of acquisition, length of residence, proficiency or offline gender knowledge. Additionally, a within-subject comparison of stimulus modalities (written vs. auditory) shows that immersed learners may show some of the effects only in the auditory modality; in non-finite verb violations, an early native-like N400 was only present for auditory stimuli. However, modality failed to influence the response to gender. Taken together, the results confirm the persistent problems of Romance learners of Dutch with online gender processing and show that they cannot be overcome by reducing task demands related to the modality of stimulus presentation.

**Keywords: second language acquisition, grammatical gender agreement, event-related potentials (ERPs), P600, modality, immersion**

## **INTRODUCTION**

Second language (L2) acquisition of many aspects of syntactic structure is known to be difficult, especially when acquisition starts later in life. A major question being debated in the literature is to what extent and under what circumstances late L2 speakers can become native-like with respect to syntax processing (e.g., Clahsen and Felser, 2006; White, 2007). The evidence is mixed; in some cases this does seem to be possible, while in other cases, it is difficult or impossible. A number of factors have been suggested to play a role in this variation, but two which have received relatively little attention are the difficulty of the target grammatical system and the potential role of modality of testing (written vs. auditory presentation). The present study investigates whether event-related potential (ERP) measures of native-likeness used in this line of research might be partially dependent on stimulus modality, as this might explain some of the inconsistency in the literature.

A structure that has frequently been used to test native-like attainment in the L2, is grammatical gender, since it has been shown to pose a major challenge to L2 learners (e.g., Hawkins, 2001; White et al., 2001; Sabourin, 2003; Blom et al., 2008). Demonstrating gender processing that is comparable to that of natives therefore forms a strong test for L2 syntax acquisition. Grammatical gender is a classification system for nouns (e.g., masculine and feminine in French, or masculine, feminine and neuter in German) which allows speakers to establish syntactic cohesion between the elements in a phrase through agreement. Because the gender of a word is typically not predictable from its meaning, learning grammatical gender involves acquiring both the knowledge of a word's gender (gender assignment) and of how gender is expressed syntactically (gender agreement or concord). Therefore, L2 learners must tag each new lemma with its corresponding gender and learn which grammatical elements in the context have to agree with it. For example in Dutch, all nouns are assigned to either the common or the neuter gender class and gender concord occurs with determiners and pre-nominal adjectives (e.g., *de*[*def*, *common*] *tuin*[*common*], the garden, *een*[*indef* ] *mooie*[*indef*, *common*] *tuin*[*common*], a beautiful garden). During processing, a comprehender must retrieve the noun's gender fast enough to establish gender concord. The question is (a) whether L2 learners manage to do so, and (b) whether they achieve this using the same processing strategies as native speakers.

Gender processing in L2 has already been the topic of numerous investigations using behavioral measures, such as grammaticality judgments, sentence-picture matching, (elicited) production, and eye tracking (for overviews, see, e.g., Grüter et al., 2012; Hopp, 2013). More recently, researchers have begun to employ ERPs to investigate native-likeness of grammatical gender processing in the L2, because ERPs are known to be highly sensitive to the immediate, unconscious on-line detection, and processing of linguistic anomalies (e.g., Osterhout and Holcomb, 1992; Molinaro et al., 2011). Studies using off-line behavioral measures (e.g., White et al., 2001, 2004; Franceschina, 2005) cannot give access to this sort of evidence, which makes interpretation of their results more difficult. Some online techniques such as eye tracking (Dussias, 2010) measure real-time language processing, but do not provide us with the qualitative evidence of potential brain mechanisms that ERPs can. The rationale of such ERP studies is that the more similar the response between native speakers and learners, the more similar the underlying neural and cognitive processing mechanisms. In other words, a comparison of ERPs in native speakers and L2 learners can tell us how native-like the latter really are.

In first language processing, gender and other (morpho)syntactic violations are found to be associated with two primary kinds of components: the left anterior negativity (LAN) and the P600. The LAN has been widely associated with morphosyntactic agreement processes (Münte et al., 1993; Friederici et al., 2000; Molinaro et al., 2011), but others claim that it is a more general index of working memory load (Kluender and Kutas, 1993; Coulson et al., 1998). The P600 has been reported for a range of syntactic and other linguistic violations (e.g., Osterhout and Holcomb, 1992; Hagoort et al., 1993; Münte et al., 1993; Burkhardt, 2007). Given the extremely heterogeneous conditions that elicit a P600, this component cannot be exclusively associated with agreement specifically, or even syntactic processing difficulties more generally, and is therefore often interpreted as a late stage of (re)analysis of information (Osterhout and Holcomb, 1992; Bornkessel-Schlesewsky and Schlesewsky, 2008). It may even reflect a more general process, such as the P300 (Gunter et al., 1997; Coulson et al., 1998; but see Osterhout and Hagoort, 1999; Frisch et al., 2003). There is however, a strong correlation between the appearance of the P600 effect and grammatical violations. In contrast, findings are more varied with respect to the presence of a LAN. In addition to the LAN and P600, some studies have found an N400, or a biphasic N400-P600 pattern (but no LAN) in response to syntactic violations (see an overview reported in Molinaro et al., 2011). This is surprising, since the N400 is a component normally associated with difficulty in semantic integration (see Kutas and Federmeier, 2011, for an overview). It has therefore been proposed that an N400 in response to syntactic agreement anomalies is likely to be a result of non-syntactic information that is needed to process the mismatch, for example information that requires lexical access (Molinaro et al., 2011). Because the LAN and N400 are variable in studies of native processing, particularly for gender agreement, we will consider the P600 to be the primary measure of nativelikeness, although we will report findings in the time window associated with the LAN/N400 (300–500 ms after presentation) as well.

ERP results regarding grammatical gender processing in the L2 have provided mixed results. A number of studies find that, at least under some conditions, sufficiently proficient L2 learners are able to show native-like ERP responses to gender violations. A set of studies investigating L2 processing of French suggests that English, German, and Spanish learners of French can show native-like ERP responses in the form of a P600 effect (Frenck-Mestre et al., 2009; Foucart and Frenck-Mestre, 2011, 2012). The same goes for English and Chinese learners of Spanish (Tokowicz and MacWhinney, 2005; Gillon Dowens et al., 2010, 2011). German and Polish learners of Dutch can also show a P600 in response to gender violations (Sabourin and Stowe, 2008; Loerts, 2012). Despite these consistent results, however, it is clear that this does not generalize to success in all aspects of gender processing, as the English and German learners also failed to respond in a native-like manner to gender in some forms of agreement (Foucart and Frenck-Mestre, 2011, 2012). Stronger yet, Romance learners of Dutch did not show sensitivity to gender agreement anomalies in the form of a P600 effect even in straightforward determiner noun agreement structures (Sabourin and Stowe, 2008). It is unclear why this group failed to exhibit the majority pattern; we will discuss some factors which might have affected their success in somewhat more detail.

One of the factors which has been considered to be central for native-like learning of a late L2 is whether a grammatical element (e.g., gender) is present in the L1. Many studies have focused on this question, but have reached different conclusions. There is some evidence that having a gender system in the L1 might be an advantage when acquiring an L2 gender system (e.g., Bruhn de Garavito and White, 2000; Hawkins, 2001; Franceschina, 2005). This is in favor of models proposing that the L1 restricts L2 acquisition (Hawkins and Chan, 1997). However, there is also evidence of L2 learners without gender systems in their L1 being able to show full acquisition of grammatical gender (White et al., 2001, 2004), which is seen as evidence against such a restriction (Schwartz and Sprouse, 1994, 1996; see also White, 1989; White et al., 2004). The presence vs. absence of gender in the L1 seems at the least to be more complicated than these views suggest, however.

The French and Spanish studies mentioned earlier show that learners with no gender in their L1 (English and Chinese speakers) can show native-like ERP responses. Further, Sabourin and Stowe (2008) find differences between two L1s which both have gender: German on the one hand and Romance learners on the other. Sabourin and Stowe themselves attribute their results to the (lack of) similarity between the native and target language of these learners: Dutch gender is in general predictable from the gender of the cognate German word due to their common historical origin, while there is no one-to-one-correspondence between Romance and Dutch gender at the lexical level. Moreover, agreement between noun and adjective is more similar in German and Dutch than the Romance languages and Dutch. Sabourin and Stowe conclude that processing routines are transferred from L1 to L2, rather than transfer of the abstract knowledge that nouns have gender, and that these routines must be similar for successful transfer (see Foucart and Frenck-Mestre, 2011, for a similar argument).

However, an explanation which assumes that similar routines in L1 are necessary for native-like processing does not account for the results of other studies mentioned above showing that even with no gender system in the L1, learners are able to show native-like effects. A different approach to the effects of L1 transfer is formulated within the Competition model (see Bates and MacWhinney, 1987). According to the competition-based account, when L1 does not contain gender there is no interference. This predicts successful outcomes for languages with no gender (Tokowicz and MacWhinney, 2005). However, when existing processing routines are transferred, they will cause interference if they are dissimilar from those required for L2 (accounting for the failure of the Romance learners of Dutch).

The target language itself may also contribute to the failure of Sabourin and Stowe's (2008) Romance group to show nativelike processing. Most of the successful studies have investigated Romance target languages. Unlike Romance or Slavic languages, which have transparent gender systems (i.e., a predictable gender category based on morphophonological patterns), Dutch is generally regarded as having an opaque gender system (Corbett, 1991; van Berkum, 1996). Although some morphological forms predict the gender of the word, these cues are only available for a relatively small proportion of the vocabulary in the language. This clearly presents a more difficult problem for the learner than gender in a more transparent language, which may certainly explain why the Romance group in the Sabourin and Stowe study failed to achieve a native-like level.

Neither L1 interference nor target language opaqueness, however, entirely accounts for the results found by Loerts (2012). Her study demonstrates that highly advanced Polish learners of Dutch can show somewhat weak, but native-like ERP responses, even though Polish agreement differs from Dutch. Loerts' results also show that an opaque system can be learned, although it may be more difficult to learn than a transparent system. Only her most proficient learners showed native-like processing (see Davidson and Indefrey, 2009, for another example of relatively low proficient learners failing to show native-like effects for gender processing in an opaque L2 system), while even fairly low proficient English learners of Spanish have been shown to respond with a clear P600 effect (Tokowicz and MacWhinney, 2005). An alternative explanation is thus that Sabourin and Stowe's (2008) Romance learners were simply not proficient enough to show online processing comparable to that of natives. Although the proficiency of the Romance group was not investigated in detail, a similar group of German learners did significantly better when tested on offline gender knowledge (Sabourin, 2003). The Romance participants in the ERP study also performed worse at the end of sentence grammaticality judgments collected during the ERP session.  A replication of the Sabourin and Stowe study with a group of learners as proficient as in the Loerts study can demonstrate whether this is the sole explanatory factor. This is one of the aims of the current study.

However, there is another factor that may have produced the difference between the two Dutch studies, which has thus far been overlooked: testing modality. Unlike virtually all the other studies summarized above, Loerts (2012) tested her Polish learners using auditory sentence presentation. She argues that the learners had acquired their L2 primarily in the auditory modality as emigrants who arrived with no formal training in their new language. Consequently, processing routines may be tuned to the auditory stimulus modality. Indeed, the experience of learning in immersion can be expected to differ substantially from a formal learning environment. Yet, the various populations that have been tested so far differ in this domain. The participants in the Romance studies summarized above included learners with extensive formal training in their L2. In many of the studies there was no immersion (Tokowicz and MacWhinney, 2005; Gillon Dowens et al., 2011) or only minimal immersion during the participants' recent residence in France (Foucart and Frenck-Mestre, 2011, 2012). Sabourin and Stowe (2008), unlike Loerts, tested a similar late immersion population using visual materials, with each word presented consecutively in the center of the screen. An alternative explanation for the lack of a native-like response in their study could thus be difficulties with the visual presentation. Below, we will speculate about why a visual ERP paradigm might, under some circumstances, be problematic.

In a typical language comprehension ERP paradigm, participants are presented with sentences displayed one word at a time at the center of a screen, at a rate of around two words per second, a technique called rapid serial visual presentation (RSVP). The advantages of this method are that the duration of stimulus presentation can be controlled (and manipulated) tightly, that eye movements, which lead to large artifacts in the EEG, are reduced to a minimum, and that making the stimulus material and time-locking the brain responses to the presentation of violations in the stimulus is relatively straightforward. Consequently, a large majority of ERP sentence comprehension studies use this method. In contrast, auditory sentence presentation is used much less frequently in ERP research. With spoken stimuli, it is more difficult to control the presentation duration of individual words. In addition, making recordings of spoken sentences is more time consuming and requires tight control of acoustic confounds (e.g., prosodic cues about upcoming information, Dimitrova et al., 2012), as well as timing issues (e.g., setting markers to millisecond precision for the events of interest).

We do not expect to find interesting differences between wordby-word reading and listening for language processing in natives (Müller et al., 1997; Hagoort and Brown, 2000; Balconi and Pozzoli, 2005). In the L1, learners develop fully automatized processing of both modalities; moreover, the auditory representation of language is automatically activated by written materials (Perfetti et al., 1992; Frost, 1998), so that the routines activated during auditory processing can be utilized as well as those specific to the written modality (Homae et al., 2002). Despite expecting comparable results for the two modalities in general, even for L1 comprehenders, consecutive word by word presentation in the middle of the screen presents a challenge under some circumstances. The optimum speed of presentation is an issue; Hopp (2010) shows that speeded RVSP presentation can make even native speakers break down in their grammaticality judgment ability, making their performance mirror that of L2 learners (see also Camblin et al., 2007, who show a case where speeded RSVP eliminates an effect which is clear in naturally produced connected speech). Conversely, studies directed at optimizing computerized text presentation on small screens have shown that too slow a presentation can also interfere with comprehension (Bernard et al., 2001). This may result from working memory and maintenance issues. Stowe (1991) showed that readers were more likely to garden-path or have difficulty in recovering from a garden path with center of the screen presentation, as opposed to presentation of words across the screen in their normal position, even when readers were allowed to pick their optimum pace.

L2 learners differ in a number of ways from native speakers, some of which can be expected to interact with modality. First, their cumulative reading experience in the L2 is likely to be substantially lower than that of native speakers. This means that their activation of the L2 via this modality can be expected to be less automatized than in native speakers (Koda, 1996). Second, interference from the writing system of the first language may lead to even less activation of the phonological form of the L2, in comparison with natives (Koda, 1999). These differences can potentially play a role for all L2 learners, but may be especially relevant for learners with less formal instruction in the language and in whom learning took place primarily via the auditory modality. The optimum speed of presentation is also likely to differ between various groups of learners and natives. This issue has received relatively little attention in the literature, but given that stimulus modality was one difference between the unsuccessful Romance group reported by Sabourin and Stowe (2008) and the relatively more successful group studied by Loerts (2012), this factor was included in the current experiment in order to determine whether it explains the different patterns seen in the two studies. A clear effect of modality would suggest that researchers need to pay more attention to this variable in their experimental designs, and might have implications for the differences between immersed and instructed learners as well.

Summarizing, the goal of the current study is to gain more insight into why some groups may show persistent problems in attaining native-like processing of grammatical gender. We investigate grammatical processing in immersed Romance L2 learners of Dutch, using the P600 as a measure of native-likeness, in order to answer the question whether late L2 learners can show nativelike syntactic processing, even if the gender marking in the L1 differs from that in the L2, which may cause interference, and the L2 gender system is relatively opaque, making it harder to recognize the grammatical agreement regularities. Following Sabourin and Stowe (2008), in addition to gender violations, which have proven difficult to master, we present our participants with nonfinite verb violations, a construction that is relatively easy to acquire, as a baseline for comparison. We compare the responses of high-proficient Romance learners with those of native speakers of Dutch. Additional measures of proficiency will be gathered from the first. A within-subject comparison of stimulus modalities allows us to determine whether the absence of a P600 effect for gender in the Sabourin and Stowe (2008) study was due to processing demands associated with the task modality.

In addition to standard group analyses of the ERP waveforms, we will closely inspect individual differences within each group. Adding these analyses has several benefits. First, lack of effects in grand mean ERP results does not necessarily mean that none of the individuals showed a native-like ERP response. Rather, a null effect might be based on opposite effects (a positive going effect in one set of individuals and a negative going effect in others) canceling each other out. In a similar way, biphasic responses can be a spurious result of averaging (Osterhout, 1997; Nieuwland and Van Berkum, 2008; Tanner and Van Hell, 2014; Tanner et al., 2014). Before we draw any strong conclusion that a group of learners' processing of gender agreement qualitatively differs from natives, it is important to identify varying patterns in each of the groups. Furthermore, there may be predictors of nativelikeness in L2 learners, such as age of acquisition, proficiency, language exposure and use, that may explain variance within the group (e.g., Weber-Fox and Neville, 1996, 1999; Rossi et al., 2006; Steinhauer et al., 2009; Tanner et al., 2014). Understanding which individual difference factors, if any, are associated with the outcome in L2 learning is a fundamental question which is difficult to answer with group-based analyses, and might also help us determine the source of some of the mixed patterns of results in L2 gender research.

### **MATERIALS AND METHODS**

#### **PARTICIPANTS**

Participant characteristics and proficiency scores can be found in **Table 1**. Forty-five participants took part in the experiment. Seven participants had to be excluded from the analyses because of too many artifacts in the EEG signal. Nineteen of the remaining participants were Romance learners of Dutch (six French, five Italians, three Romanians, five Spanish). The remaining 19 participants were native speakers of Dutch. All participants were right handed, neurologically unimpaired and did not have any problems with hearing, speaking, or writing. Prior to conducting any procedures, written consent was obtained from all participants for the study, which was approved by the local ethics committee. Participants were fully debriefed at the end of the experiment and received a small fee for participation.

All learners had moved to the Netherlands at or after the age of 16 and had been immersed in the L2 context for at least 5 years at the time of testing. The learners had very little to no exposure to Dutch before immigration. They were asked to indicate the frequency of use of Dutch in daily life: a composite score for L2 use was calculated based on questions about language use at home (with partner and children), outside of the home (at the workplace and other), and use of Dutch media. They additionally answered questions about their use of Dutch in a specific modality: they estimated the percentage of use of the L2 in the visual modality (i.e., reading/writing) compared to the auditory modality (i.e., speaking/listening), both during learning of Dutch at onset of immigration and during everyday life at the time of testing.

L2 proficiency was assessed by means of several (written) measures. A pre-selection on the basis of a pre-test in the form of 20 grammar items of the Dutch DIALANG Placement Test (adapted from http://www.lancaster.ac.uk/researchenterprise/ dialang/about.html) ensured that all participants had a relatively high level of proficiency in Dutch. Participants had to complete at least 13 of the items correctly to be selected for participation. Another proficiency measure was taken in the lab, in the form of a C-test (constructed by Keijzer, 2007), which consisted of two texts containing gaps where parts of some words had been left out. The participants' task was to fill the gaps. After the EEG experiment, participants were also asked to complete

**Table 1 | Means (and ranges) of participant characteristics and scores on proficiency measures, and significance of between-group comparisons (Mann-Whitney** *U***-test).**

aComposite score based on language use inside and outside of the home and use of Dutch media.

bPercentage of L2 use in the visual modality (i.e., reading/writing) compared to the auditory modality (i.e., speaking/listening) during learning of Dutch at onset of immigration.

cPercentage of L2 use in the visual modality (i.e., reading/writing) compared to the auditory modality (i.e., speaking/listening) in everyday life at the time of testing. dPercentage of correct responses on the C-test (spelling errors were not penalized).

ePercentage of correct responses (i.e., a minimum of 2/3 instances of each item assigned correctly) on the gender assignment task.

fRatings on a 5-point scale with five as highest level of skill in Dutch.

an offline gender assignment task. This task was used to test the participants' knowledge of the grammatical gender of the critical nouns used in the EEG experiment. In addition to these measures, learners rated their L2 Dutch in terms of reading, writing, speaking, and listening proficiency on a Likert-scale between 1 (very bad) and 5 (very good). Participants' scores on the proficiency measures can be found in **Table 1**.

#### **MATERIALS**

The design and materials of the EEG experiment were largely based on work by Loerts (2012), who studied L2 gender and nonfinite verb processing in natives and Slavic learners of Dutch. One hundred and forty-four experimental sentences were created (see **Table 2** for examples, the full list of sentences can be found in the Supplementary Material, Data Sheet 1). Forty-eight of the sentences1 were used to test non-finite verb agreement. Half of these contained an infinitive and the other half a past participle verb. For their ungrammatical counterparts, these verbs were altered into their participial or infinitival form, respectively. The other 96 sentences were used to test grammatical gender agreement. In these sentences, the determiner either agreed in gender with the following noun or violated gender concord. Determiner and noun were either adjacent, or non-adjacent (with an adjective intervening between the determiner and noun). Only highly frequent Dutch target nouns and verbs were used (nouns: mean = 2.16, range = 0.78–3.08; verbs: mean = 2.46, range = 0.95– 4.05, on log lemma frequency of occurrence per million taken from the CELEX corpus: Baayen et al., 1995). Finally, 122 wellformed filler sentences were included. These filler sentences were added to raise the overall proportion of correct sentences to about 3/4, making the task more similar to natural language processing.

For the auditory part of the experiment, spoken forms of all sentences were recorded. Each sentence was read aloud by a female native speaker with a standard Dutch accent who was trained to produce correct and incorrect sentences with normal intonation. Despite training, acoustic confounds, such as subtle prosodic cues to the upcoming ungrammaticality remain possible (Dimitrova et al., 2012). To prevent any influence of such confounds, each sentence was presented in its original form or in a digitally spliced version, constructed by cross-splicing the original recordings of grammatical and violation sentences, cutting at the onset of the determiner for the gender condition, or the verb

1Because of the large number of factors in the current design, it was not possible to get a high number of trials per condition without making the experiment too long, which in all probability would have resulted in severe fatigue effects in our data. We realize that as a result, the number of trials per condition is on the low side, particularly for the non-finite verb condition. However, highly salient agreement errors, such as the non-finite verb agreement violations used in the current study, have been shown to elicit large ERP effects. As the results section of this paper shows, even with this low number of trials we had sufficient power to find significant effects in this condition. In the less salient gender condition however, there was double the amount of trials per condition to ensure sufficient power.

#### **Table 2 | Example materials of the EEG experiment.**

Critical targets, where the ERP was measured, are underlined.

in the non-finite verb condition. Noise reduction and volume normalization were applied to all sound files.

A within-subject design was employed to test the effects of modality within the same group of subjects. Eight experimental lists were created using a Latin Square design, crossing the factors modality (visual, auditory), correctness (correct, incorrect), and splicing (spliced, unspliced), to ensure each participant was presented with only one version of each sentence and an equal number of each type. Each list was presented to two or three participants from each group, and each participant saw only one list.

#### **PROCEDURE**

Event-related potentials were recorded while participants listened to or read the sentences. After each sentence, the participant had to make a grammaticality judgment. Participants were comfortably seated in an electrically shielded and sound attenuated chamber. The sentences were presented using E-prime (Schneider et al., 2002a,b), which in addition recorded accuracy with respect to the grammaticality judgments. Visual stimuli were presented on a computer screen in front of the participants. Speakers were placed to the left and right side of the screen. Visual sentences were presented at a rate of two words per second: each word was presented for 250 ms, followed by 250 ms blank screen. Auditory sentences were presented at normal speech rate. Participants were asked to avoid moving any parts of their body and not to move their eyes or blink during sentence presentation. The experiment consisted of four blocks: either two visual blocks followed by two auditory blocks or the reverse. The duration of the breaks between blocks was determined by the participant. Altogether, the EEG experiment lasted about 1 h.

Subsequently, participants were asked to fill in the pen and paper C-test. Finally, they performed a gender assignment task on a computer. The target words of the EEG experiment were presented in randomized order, each item appearing three times. Participants were instructed to indicate, by a mouse click on either the common ("de") or neuter ("het") definite article, whether they thought the word had common or neuter gender in Dutch.

#### **EEG RECORDING AND ANALYSIS**

The continuous EEG (500 Hz/22 bit sampling rate) was recorded from 54 Ag/AgCl scalp electrodes mounted into an elastic cap (Electro Cap International, Inc.) according to the international extended 10–20 system (see **Figure 1** for recording sites). To

monitor eye-movements, four additional electrodes were placed on the outer canthi of each eye and above and below the left eye. Scalp electrode signals were measured against a common reference during recording. Impedances were reduced to below 10 k-2 . The amplifier (TMS international) measured DC with a digital FIR filter (cutoff frequency 130 Hz) to avoid aliasing. After acquisition, the raw data were further processed with Brain Vision Analyzer 2.0.4. The data were re-referenced to the average of two electrodes placed over the left and right mastoids and digitally filtered with a high-pass filter at 0.1 Hz and lowpass filter at 40 Hz. The data were segmented, time-locked to the onset of the critical target (from 500 ms before to 1400 ms

2In some instances, some temporal and frontal electrodes could only be reduced to below 20 k-.

after stimulus onset). Average ERPs were formed without regard to behavioral responses, from trials free of muscular and ocular artifacts; the latter were corrected using the Gratton and Coles procedure (1989). Individual channel artifacts led to rejection of 0.5% of the data in the learner group and 0.6% in the native group. A baseline period was set from 200 to 0 ms before onset of the critical words to normalize the data. A total of 10 regions of interest (ROIs), containing five or six electrodes each, were used for analyses (depicted in **Figure 1**).

We analyzed amplitudes of the ERP waveforms in the timewindows in which a LAN/N400 and P600 are to be expected: 300–500 and 600–1200 ms after stimulus onset. The latter window is somewhat longer than is typical in P600 studies in monolinguals, because the P600 in L2 learners can be somewhat delayed (Weber-Fox and Neville, 1996; Hahne, 2001; Rossi et al., 2006; Sabourin and Stowe, 2008). For grand mean analyses, ANOVAs were calculated within each time window and *sentence structure* (non-finite verb, grammatical gender) separately, using the ezANOVA function of the ez package (version 4.2.2: Lawrence, 2013), implemented in R (version 3.1.0: R Core Team, 2014). The analyses included *correctness* (grammatical, violation) and *modality* (visual, auditory) as within-participants factors, and *group* (natives, learners) as between-participants factor. Data from lateral (left and right frontal, temporal, parietal, and occipital ROIs) and medial (middle frontal and middle parietal ROIs) regions were treated separately in order to identify topographic and hemispheric differences. For the lateral regions, the ANOVA also included *hemisphere* (left, right) and *anteriorposterior* (frontal, temporal, parietal, occipital) as within participants factors. For the medial regions, *anterior-posterior* (frontal, parietal) was the only topographical factor in the ANOVA. The Greenhouse-Geisser correction was applied for violations of the sphericity assumption. Only main effects of, and interactions with, *correctness* are reported. In the presence of a significant higher-level interaction, lower-level interactions, and main effects are not interpreted. False discovery rate correction (Benjamini and Hochberg, 1995) was applied for follow-up tests to control for Type 1 error. Additional regression analyses, performed in R version 3.1.0 using the lm function of the lme4 package (version 1.1.6: Bates et al., 2014) will be described together with the results.

## **RESULTS**

#### **BEHAVIORAL RESULTS**

The percentages of accurate grammaticality judgments per *group*, *sentence structure*, and *modality* are shown in **Figure 2**. A Three-Way ANOVA was conducted on the arcsine transformed proportions of correct responses to stabilizes variance and normalize the data (mean and SDs reported below are from the untransformed percentages). The ANOVA revealed a significant main effect of *group*, *F*(1, 36) = 53.24, *p* < 0.001, with the learners giving fewer correct responses than the natives (mean = 71.1, *SD* = 17.8 vs. mean = 93.0, *SD* = 11.5). The main effect of *sentence structure*, *F*(1, 36) = 41.66, *p* < 0.001, shows that the average performance is worse in the gender condition. However, there is also a significant interaction between *group* and *structure*, *F*(1, 36) = 5.55, *p* = 0.024. Paired comparisons show that the difference between structures is highly significant in the learner group [*t*(62.9) = 4.91, *p* < 0.001, gender mean = 62.8, *SD* = 14.1; non-finite verb mean = 79.5, *SD* = 17.3]. There is a smaller, but still significant difference between structures in the native group [*t*(59.7) = 2.42, *p* = 0.019, gender mean = 92.2, *SD* = 6.2; verbs mean = 93.8, *SD* = 15.1]. Interestingly, with respect to one of our research questions, there is a significant main effect of *modality*, *F*(1, 36) = 8.37, *p* = 0.006, with the percentage of correct responses in the auditory condition being somewhat lower than in the visual condition (mean = 79.5, *SD* = 20.0 vs. mean = 84.6, *SD* = 16.7). There are however no significant interactions between *modality* and *group*, *modality* and *structure*, or *group*, *modality,* and *structure* (all *F*s < 3).

#### **ERP RESULTS: GRAND MEAN ANALYSES**

**Figures 3**, **4** show the grand mean ERP waveforms for natives and learners, respectively. Results of the omnibus ANOVAs are provided in the Supplementary Material (Data sheet 2). Significant results and follow-up analyses will be described below.

## *Non-finite verb agreement*

In the 300–500 ms window, the lateral omnibus ANOVA for the non-finite verb condition showed a significant *correctness* by *anterior-posterior* interaction, *F*(3, 108) = 6.02, *p* = 0.011; followup analysis revealed that the effect of *correctness* reached significance in posterior regions only [frontal, *F*(1, 36) = 0.52, *p* = 0.476; temporal, *F*(1, 36) = 4.16, *p* = 0.065; parietal, *F*(1, 36) = 14.70, *p* = 0.002; *F*(1, 36) = 11.77, *p* = 0.004], with the incorrect condition showing more negative voltages than the correct condition. Due to a marginally significant *group* by *correctness* interaction in the omnibus ANOVA, *F*(1, 36) = 3.65, *p* = 0.064, another follow-up analysis was conducted separately for natives and learners. This analysis revealed that the main effect of *correctness* was significant in natives, *F*(1, 18) = 7.36, *p* = 0.028, but not in learners, *F*(1, 18) = 0.08, *p* = 0.780. The medial omnibus ANOVA revealed a significant main effect of *correctness*, *F*(1, 36) = 9.22, *p* = 0.004, with more negative voltages for the incorrect than the correct condition. Due to a marginally significant *correctness* by *anterior-posterior* interaction, *F*(1, 36) = 3.33, *p* = 0.076, a follow-up analysis was conducted, which again revealed that the effect of correctness reached significance in the posterior region only [frontal, *F*(1, 36) = 2.77, *p* = 0.105; parietal, *F*(1, 36) = 14.55, *p* = 0.002]. Additionally, the omnibus ANOVA showed a marginally significant *group* by *correctness* by *modality* interaction, *F*(1, 36) = 3.56, *p* = 0.067; but follow-up analyses failed to reveal a significant modality effect in either of the groups [*correctness* by *modality* interaction: natives, *F*(1, 18) = 0.72, *p* = 0.407; learners, *F*(1, 18) = 4.12, *p* = 0.114]. The main effect of *correctness* reached significance on its own in natives, *F*(1, 18) = 6.26, *p* = 0.044, but not in learners, *F*(1, 18) = 3.00, *p* = 0.100. Since visual inspection of the grand mean waveforms seems to suggest a possible negativity in medial regions for learners in the auditory condition, and finding a native-like effect in this time window for L2 learners is unusual, we performed an additional follow-up analysis separately for each modality in learners, which showed a significant *correctness* effect in the auditory, *F*(1, 18) =

6.18, *p* = 0.046, but not the visual modality, *F*(1, 18) = 0.43, *p* = 0.522.

In the later time window (600–1200 ms), the lateral omnibus ANOVA showed a significant *group* by *correctness* by *anterior-posterior* interaction, *F*(3, 108) = 5.95, *p* = 0.008. Follow-up analysis revealed a significant main effect of *correctness* in both groups [natives, *F*(1, 18) = 20.39, *p* = 0.001; learners, *F*(1, 18) = 14.16, *p* = 0.001], with more positive amplitudes in the incorrect compared to the correct condition. A significant *correctness* by *anterior-posterior* interaction was present for natives only [natives, *F*(3, 54) = 23.51, *p* = 0.001; learners, *F*(3, 54) = 1.97, *p* = 0.169], which was driven by the fact that the positivity in natives was significant in the temporal, *F*(1, 18) = 16.32, *p* = 0.001, parietal, *F*(1, 18) = 36.07, *p* = 0.001, and occipital region, *F*(1, 18) = 35.54, *p* = 0.001, but not the frontal region, *F*(1, 18) = 0.00, *p* = 0.985. The medial omnibus ANOVA revealed a significant *correctness* by *anteriorposterior* interaction, *F*(1, 36) = 22.93, *p* < 0.001; a follow-up analysis showed that the *correctness* effect is stronger in the

parietal, *F*(1, 36) = 68.36, *p* < 0.001, than the frontal region, *F*(1, 36) = 29.15, *p* < 0.001.

It is apparent from these grand mean analyses that non-finite verb agreement violations are associated with a biphasic pattern of an N400 followed by a P600 in natives. The lack of significant effects for the frontal regions rules out a LAN effect in the 300–500 ms time window. Learners' responses are very similar to natives' in the later time-window (P600). However, in the early time window learners fail to show a native-like effect (N400) in the visual condition, and only show a smaller and less broadly distributed N400 compared to natives in the auditory condition.

#### *Gender agreement*

In the 300–500 ms window, the lateral omnibus ANOVA for the gender condition showed a significant *correctness* by *modality* by *anterior-posterior* interaction, *F*(3, 108) = 3.90, *p* = 0.039, and a *group* by *correctness* by *modality* by *hemisphere* interaction, *F*(1, 36) = 5.24, *p* = 0.028. Follow-up analyses conducted separately for natives and learners revealed a significant *correctness* by *modality* by *anterior-posterior* interaction in natives, *F*(3, 54) = 6.28, *p* = 0.016, but no significant effects in learners (all *F*s < 2.03). However, in natives, neither the main effect of *correctness* nor the *correctness* by *anterior-posterior* interaction reached significance in either of the modalities analyzed separately (all *F*s < 3.90). The medial omnibus ANOVA showed a significant *group* by *correctness* interaction, *F*(1, 36) = 4.30, *p* = 0.045. However, follow-up analyses failed to find a significant main effect of *correctness*, or any of its interactions, in either of the groups analyzed separately (all *F*s < 4.23).