The Role Of Individual Differences In Bilingual Language Processing

In this thesis, I investigated the neural correlates of bilingualism, and how individual differences in both brain and behaviour affect second language processing. To date, theories of bilingualism have tended to treat bilinguals as a uniform group, while in practice they vary greatly in both experience and ability. By examining how individual differences in proficiency and age of acquisition contribute to second language learning and processing, I sought to address this issue. In chapter two, I used event-related potentials to investigate how age of acquisition and proficiency modulate processing of a novel versus a grammatical rule that is similar across languages. I provided evidence that both age of acquisition and proficiency, in addition to bilingual status, modulate processing of a novel grammatical rule. In contrast, only proficiency predicted processing of a similar grammatical rule. Thus, while the similarities between languages affect second language processing, the degree of their influence is modulated by individual differences in second language experience. In chapter three, I used functional magnetic resonance imaging to investigate how bilinguals represent their shared, integrated lexicons in the brain. Several areas showed differing patterns of representation, while univariate analyses in these areas showed no differences in levels of activation. The separate representation of first and second languages in these regions provides a possible basis for the neurocognitive realization of a shared, integrated lexicon proposed by many theories of bilingualism. In chapter four, I used diffusion tensor imaging to investigate how AoA modulates white matter microstructure, examining white matter tracts in the left and right hemispheres that underlie language processing. Group statistics suggested that second language speakers as a whole may have lower fractional anisotropy, while the within-group analysis revealed that white matter integrity is sensitive to individual experience. Chapter five discusses the relevant findings of the previous chapters, and considers how individual differences arise. Next, I make recommendations for theories of bilingual language processing, and close with a discussion of future research directions

Verbing and nouning in French : toward an ecologically valid approach to sentence processing

La présente thèse utilise la technique des potentiels évoqués afin d’étudier les méchanismes neurocognitifs qui sous-tendent la compréhension de la phrase. Plus particulièrement, cette recherche vise à clarifier l’interaction entre les processus syntaxiques et sémantiques chez les locuteurs natifs et les apprenants d’une deuxième langue (L2). Le modèle “syntaxe en premier” (Friederici, 2002, 2011) prédit que les catégories syntaxiques sont analysées de façon précoce: ce stade est reflété par la composante ELAN (Early anterior negativity, Négativité antérieure gauche), qui est induite par les erreurs de catégorie syntaxique. De plus, ces erreurs semblent empêcher l’apparition de la composante N400 qui reflète les processus lexico-sémantiques. Ce phénomène est défini comme le bloquage sémantique (Friederici et al., 1999). Cependant, la plupart des études qui observent la ELAN utilisent des protocoles expérimentaux problématiques dans lesquels les différences entre les contextes qui précèdent la cible pourraient être à l’origine de résultats fallacieux expliquant à la fois l’apparente “ELAN” et l’absence de N400 (Steinhauer & Drury, 2012). La première étude rééevalue l’approche de la “syntaxe en premier” en adoptant un paradigme expériemental novateur en français qui introduit des erreurs de catégorie syntaxique et les anomalies de sémantique lexicale. Ce dessin expérimental équilibré contrôle à la fois le mot-cible (nom vs. verbe) et le contexte qui le précède. Les résultats récoltés auprès de locuteurs natifs du français québécois ont révélé un complexe N400-P600 en réponse à toutes les anomalies, en contradiction avec les prédictions du modèle de Friederici. Les effets additifs des manipulations syntaxique et sémantique sur la N400 suggèrent la détection d’une incohérence entre la racine du mot qui avait été prédite et la cible, d’une part, et l’activation lexico-sémantique, d’autre part. Les réponses individuelles se sont pas caractérisées par une dominance vers la N400 ou la P600: au contraire, une onde biphasique est présente chez la majorité des participants. Cette activation peut donc être considérée comme un index fiable des mécanismes qui sous-tendent le traitement des structures syntagmatiques. La deuxième étude se concentre sur les même processus chez les apprenants tardifs du français L2. L’hypothèse de la convergence (Green, 2003 ; Steinhauer, 2014) prédit que les apprenants d’une L2, s’ils atteignent un niveau avancé, mettent en place des processus de traitement en ligne similaires aux locuteurs natifs. Cependant, il est difficile de considérer en même temps un grand nombre de facteurs qui se rapportent à leurs compétences linguistiques, à l’exposition à la L2 et à l’âge d’acquisition. Cette étude continue d’explorer les différences inter-individuelles en modélisant les données de potentiels-évoqués avec les Forêts aléatoires, qui ont révélé que le pourcentage d’explosition au français ansi que le niveau de langue sont les prédicteurs les plus fiables pour expliquer les réponses électrophysiologiques des participants. Plus ceux-ci sont élevés, plus l’amplitude des composantes N400 et P600 augmente, ce qui confirme en partie les prédictions faites par l’hypothèse de la convergence. En conclusion, le modèle de la “syntaxe en premier” n’est pas viable et doit être remplacé. Nous suggérons un nouveau paradigme basé sur une approche prédictive, où les informations sémantiques et syntaxiques sont activées en parallèle dans un premier temps, puis intégrées via un recrutement de mécanismes contrôlés. Ces derniers sont modérés par les capacités inter-individuelles reflétées par l’exposition et la performance.The present thesis uses event-related potentials (ERPs) to investigate neurocognitve mechanisms underlying sentence comprehension. In particular, these two experiments seek to clarify the interplay between syntactic and semantic processes in native speakers and second language learners. Friederici’s (2002, 2011) “syntax-first” model predicts that syntactic categories are analyzed at the earliest stages of speech perception reflected by the ELAN (Early left anterior negativity), reported for syntactic category violations. Further, syntactic category violations seem to prevent the appearance of N400s (linked to lexical-semantic processing), a phenomenon known as “semantic blocking” (Friederici et al., 1999). However, a review article by Steinhauer and Drury (2012) argued that most ELAN studies used flawed designs, where pre-target context differences may have caused ELAN-like artifacts as well as the absence of N400s. The first study reevaluates syntax-first approaches to sentence processing by implementing a novel paradigm in French that included correct sentences, pure syntactic category violations, lexical-semantic anomalies, and combined anomalies. This balanced design systematically controlled for target word (noun vs. verb) and the context immediately preceding it. Group results from native speakers of Quebec French revealed an N400-P600 complex in response to all anomalous conditions, providing strong evidence against the syntax-first and semantic blocking hypotheses. Additive effects of syntactic category and lexical-semantic anomalies on the N400 may reflect a mismatch detection between a predicted word-stem and the actual target, in parallel with lexical-semantic retrieval. An interactive rather than additive effect on the P600 reveals that the same neurocognitive resources are recruited for syntactic and semantic integration. Analyses of individual data showed that participants did not rely on one single cognitive mechanism reflected by either the N400 or the P600 effect but on both, suggesting that the biphasic N400-P600 ERP wave can indeed be considered to be an index of phrase-structure violation processing in most individuals. The second study investigates the underlying mechanisms of phrase-structure building in late second language learners of French. The convergence hypothesis (Green, 2003; Steinhauer, 2014) predicts that second language learners can achieve native-like online- processing with sufficient proficiency. However, considering together different factors that relate to proficiency, exposure, and age of acquisition has proven challenging. This study further explores individual data modeling using a Random Forests approach. It revealed that daily usage and proficiency are the most reliable predictors in explaining the ERP responses, with N400 and P600 effects getting larger as these variables increased, partly confirming and extending the convergence hypothesis. This thesis demonstrates that the “syntax-first” model is not viable and should be replaced. A new account is suggested, based on predictive approaches, where semantic and syntactic information are first used in parallel to facilitate retrieval, and then controlled mechanisms are recruited to analyze sentences at the interface of syntax and semantics. Those mechanisms are mediated by inter-individual abilities reflected by language exposure and performance

An investigation into the processing of unaccusativity and PHI-Features: evidence from native and non-native speakers of basque and spanish.

247 p.Tesi honetan argumentu egitura, tasunak eta natibo/ez-natiboen prozesamendua jorratu ditut, eta horretarako zehaztasuna, erreakzio denborak eta garunaren aktibitatea neurtu ditut. Lehenik eta behin,Perlmutter-ek (1978) Hipotesi Ez akusatiboa (HE) aurkeztu zuen, eta defendatu zuen badirela bi predikatu iragangaitz mota: alde batetik, ez akusatiboak, argumentua bakarra objektu gisa sortu eta gai rol semantikoa dutenak; eta beste alde batetik, ez ergatiboak, argumentu bakarra subjektu gisa sortu eta egile rol semantikoa dutenak. Euskaraz eta gaztelaniaz erakutsi dut garun aktibitate ezberdina sortzen dela predikatu ez akusatibo eta ez ergatiboak prozesatzean, eta erakutsi dut predikatuen prozesamendu kostuak aldatu egiten direla hizkuntzaren kasu ezarketaren arabera.Bigarrenik, phi-tasunen prozesamendua aztertu dut. ERPen bitartez, pertsona eta numero tasunak nola prozesatzen diren ikertu dut euskaraz eta gaztelaniaz, eta emaitzek erakutsi dute pertsona eta numeroa ezberdin prozesatzen direla euskaraz zein gaztelaniaz.Hirugarrenik eta azkenik, tesion natiboen eta ez-natiboen prozesamendua ikertu dut. Ez dago argi ez natiboek nola prozesatzen duten hizkuntza. Hemen, natiboak eta maila altuko elebidun goiztiarrak ikertu eta konparatu ditut bai euskaraz, eta baita gaztelaniaz ere. Tesi honen bitartez, erakutsi da maila altuetan,eta jabekuntza goiztiarretan, ez-natiboak hizkuntza natiboen gisara prozesatzeko gai direla

Number Specification in L2 processing of Norwegian adult L2 English speakers: Time-frequency representation (TFR) analysis

This thesis investigates the processing of non-local agreement violations and whether they are affected by double marking from a determiner-number specification in Norwegian L2 speakers of English. We tested non-local subject-verb agreement, a mismatch between Norwegian and English, and the double marking on the number of the noun that is a common feature of the two languages by using online Grammaticality Judgement test (GJT) during EEG (electroencephalogram) recording. There were four conditions to test the participants’ sensitivity towards determiner number specification: (1) Grammatical unspecified, (2) ungrammatical unspecified, (3) grammatical specified, (4) ungrammatical specified. The EEG data were analyzed with TFRs (time-frequency references) to observe the changes in different frequency bands of neural oscillations. Behavioural and neural responses to the sentences were compared to understand the neural mechanisms regarding the interaction between non-local agreement violations and determiner-number specification. The results showed no evidence for an interaction between specificity and grammaticality. The specificity did not seem to affect participants’ judgment of the grammaticality. That is, we did not see any change in the theta band (4-8 Hz); however, a relative decrease in the activation for the ungrammatical items vs grammatical items in the alpha band (8-12 Hz) and a relative decrease in the activation for the number-specified items vs number-unspecified items in alpha bands (8-12 Hz) was observed. The alpha band reactivity observed during language comprehension does not necessarily reflect the linguistic analyses but the attention. Alpha band decrease is explained as the engagement of the additional attentional resources to explain a faulty representation. The results of the behavioural data showed that the participants were better when judging the grammatical sentences than the ungrammatical sentences, and the unspecified grammatical sentences were judged more accurately than the other three conditions. The findings of the current study suggest that the agreement violation in GJT led the participants to have increased attentional process demands as they needed to judge the mismatching property between their L1 Norwegian and L2 English

Semantic radical consistency and character transparency effects in Chinese: an ERP study

BACKGROUND: This event-related potential (ERP) study aims to investigate the representation and temporal dynamics of Chinese orthography-to-semantics mappings by simultaneously manipulating character transparency and semantic radical consistency. Character components, referred to as radicals, make up the building blocks used dur...postprin

N400 evidence for musical facilitation of word boundary identification in second language exposure

Lexical acquisition requires the ability to identify word boundaries in a continuous auditory speech stream. This complex task is even more challenging when learning a new language in adulthood. Previous studies have shown that word boundary identification can be enhanced by pairing musical tones with native language phonemes. The objective of this dissertation study was to investigate whether musical tones also have this effect in a novel pseudo-language that uses non-native speech sounds. The N400, a brain event-related potential that has been linked with familiarity responses and detection of statistical regularities during exposure to pseudowords, provides an index of brain activation associated with semantico-lexical processing. In this study, language-like stimuli incorporating a French phoneme (a high, front, rounded vowel that is not part of the English phonetic inventory) were presented to typically developing English monolingual adults. Participants were presented to one of two types of exposure conditions for 7 minutes: monotone presentation of the concatenated language-like stimuli; or the same speech stream with a musical tone associated with each syllable. The exposure protocol was based on Schön, Boyer, Moreno et. al. (2008). Exposure was followed by a lexical decision task, requiring participants to distinguish “words” (heard during the exposure in a concatenated speech stream) from “part words” (end of one word and the beginning of another, crossing word boundaries). High-density EEG was recorded during the lexical decision and analyzed offline to determine N400 event-related responses to the stimuli in each condition. Although behavioral measures did not reveal any significant differences between groups or conditions, we found a N4 significantly different response to “partword” in the tone-exposed group, compared to the monotone. This difference only occurred in a frontal region with a right-hemisphere bias, and was not found to be significant over the left hemisphere. This difference suggests that participants in the tone group were supported in differentiating “words” from “partwords”, supporting the view that the inclusion of tonal information is beneficial in the early stages of L2 lexical learning

Syntax through the looking glass: A review on two-word linguistic processing across behavioral, neuroimaging and neurostimulation studies

In recent years a growing number of studies on syntactic processing has employed basic two-word constructions (e.g., “the tree”) to characterize the fundamental aspects of linguistic composition. This large body of evidence allows, for the first time, to closely examine which cognitive processes and neural substrates support the combination of two syntactic units into a more complex one, mirroring the nature of combinatory operations described in theoretical linguistics. The present review comprehensively examines behavioural, neuroimaging and neurostimulation studies investigating basic syntactic composition, covering more than forty years of psycho- and neuro-linguistic research. Across several paradigms, four key features of syntactic composition have emerged: (1) the rule-based and (2) automatic nature of the combinatorial process, (3) a central role of Broca’s area and the posterior temporal lobe in representing and combining syntactic features, and (4) the reliance on efficient bottom-up integration rather than top-down prediction