Hemispheric differences in figurative language processing: Contributions of neuroimaging methods and challenges in reconciling current empirical findings

a b s t r a c t The following review critically synthesizes the literature on hemispheric differences in idiom and metaphor comprehension. It has long been debated whether figurative language is inherently different from literal language and is processed specifically in the right hemisphere (RH), or rather, whether figurative and literal language form a continuum rather than a dichotomy, and call upon a similar network of brain areas. In this paper, a number of neuropsychological, behavioral and neuroimaging studies are reviewed in the context of major theoretical accounts of metaphor and idiom comprehension. Specifically, the role played by the RH in metaphor and idiom processing is evaluated, and advancements that neuroimaging methods have made to our understanding of figurative language comprehension are assessed. This review also highlights a number of critical methodological discrepancies between studies, and emphasizes how such inconsistencies in operational definitions, stimuli and tasks pose a serious challenge to reconciling the debate on hemispheric differences, and do not allow for a clear-cut conclusion of which neural networks underlie figurative language processing

The case of the non-native-like first-language: neurophysiological investigations of first-language attrition and second-language processing

It is a widespread notion that mastering a second-language (L2) to the level of a native-speaker is more difficult in adulthood than in childhood. For more than half a century, researchers have attributed linguistic differences between "late" L2-learners and native-speakers to a neurobiological cause – with maturation, the brain has been argued to lose the plasticity required to change with experience, such that any subsequent language will rely on different brain areas or compensatory processing strategies than those underlying the native-language. Conversely, it is assumed that one's native-language has a privileged and stable status in the brain, as its neural connections are established and hard-wired in the early years of life. However, for the vast majority of L2 learners, the late-learned language is typically confounded with lower exposure, use and proficiency relative to the native-L1, and it is unresolved whether these experiential factors, rather than limitations of neuroplasticity, determine neurocognitive profiles of L2-processing.The work presented in this dissertation was motivated by this controversial debate and turns to a unique population of bilinguals for a new perspective. First-generation immigrants who move to a new country in adulthood become predominantly exposed to and highly-proficient in the late-acquired L2, while experiencing gradual changes or "attrition" in their L1. Three studies using highly-sensitive event-related brain potenials (ERPs) were conducted to explore two main questions: (1) Do the neurocognitive mechanisms underlying L1-processing remain "native-like" despite attriters' shift in exposure, use and/or proficiency from the L1 to the L2?; (2) Does proficiency shape neurocognitive responses during language-processing, regardless of whether the language being processed is the L1 or L2? We tested morphosyntactic (Study 1) and lexical-semantic (Study 2 and 3) processing of Italian and English in four groups of speakers: (1) Italian-English immigrants who were predominantly-exposed to English and who reported negative changes to their Italian; (2) English-Italian late L2-learners who were highly-proficient in Italian; (3) monolingual Italian native-speakers residing in Italy, and (4) monolingual English native-speakers. The specific linguistic phenomena we chose to examine were elements that were either subtle or difficult aspects of grammar and vocabulary, or that were candidates of cross-linguistic competition / transfer between Italian and English. This dissertation provides some of the first neurocognitive evidence of L1-attrition, although differences from non-attriting native-speakers may be subtle and observable at the brain level before they become overtly apparent in behavior. In showing processing differences in a group of native-speakers who lived in an exclusively monolingual context until adulthood, our findings are compatible with the view that there is ongoing neuroplasticity for language beyond an early developmental period. The possible downside of this plasticity is that the L1 may not be as stable as it is often assumed. The three studies also emphasize the crucial role of proficiency in modulating the brain's responses to language, regardless of age-of-acquisition, and highlight the possibility of parallels between L1 attrition and L2 acquisition. Our results also indicate that attriters also engage in more conscious or controlled processes that depend both on experimental properties as well as on experiential circumstances that are inherently part of attrition (e.g., increased attention, more cautious approach, second-thoughts). This work therefore has significant implications for research on the neurocognition of language, and highlights the usefulness of studying language-attrition as a bridge between first- and second-language processing.Il est généralement pris pour acquis que la maîtrise d’une langue seconde (L2) au niveau d’un locuteur natif est plus difficile à atteindre à un âge adulte que pendant l’enfance. Pendant plus d’un demi-siècle, les chercheurs ont attribué ces différences entre locuteurs natifs et bilingues tardifs à une cause neurobiologique: Au cours du développement, le cerveau perdrait progressivement de sa plasticité requise pour se modifier selon l’expérience, de sorte que toute langue acquise subséquemment serait basée sur des aires cérébrales ou des stratégies de traitement différentes de celles sous-tendant la langue première. En contraste avec cette hypothèse, il est généralement proposé que la langue première (L1) jouit d’un statut privilégié et stable dans le cerveau, et que ses connections neurales sont fixes et bien établies. Toutefois, pour la majorité des personnes bilingues, la langue seconde s’accompagne d’une exposition, d’un usage et d’une expertise moindres par rapport à leur langue première, et la question de savoir dans quelle mesure ces facteurs liés à l’expérience sont à la source des profiles de traitement de L2 au delà des limites de plasticité cérébrale demeure irrésolue. Ce débat controversé est au cœur de la présente thèse, laquelle se concentre sur un bassin unique de personnes bilingues pour l’étudier selon une approche nouvelle. En particulier, les immigrants adultes de première génération sont exposés à L2 de façon prédominante et en atteignent un niveau de maîtrise élevé tout en subissant des changements graduels – une «attrition» – dans L1. Nous présentons trois études exécutées selon la méthode très sensible des potentiels évoqués (PÉs) afin d’explorer deux questions de recherche principales: (1) Les mécanismes neurocognitifs sous-tendant le traitement de L1 demeurent-ils à un «niveau natif» malgré le changement radical d’exposition de L1 à L2?, et (2) le niveau de compétence est-il à la sources des réponses neurocognitives de traitement du langage, que celui se passe en L1 ou en L2 ?Nous avons testé le traitement morphosyntaxique (Étude 1) et lexico-sémantique (Études 2 et 3) de l’italien et de l’anglais dans quatre groupes de locuteurs: (1) des immigrants italo-anglophones exposés principalement à l’anglais mais rapportant des changements négatifs sur leur maîtrise de l’italien; (2) des apprenants italo-anglophones tardifs de l’anglais mais compétents en italien; (3) des locuteurs monolingues natifs de l’italien résidant en Italie et (4) des locuteurs monolingues de l’anglais. Les phénomènes linguistiques que nous avons choisi d’étudier portaient sur des aspects grammaticaux ou lexicaux subtils, ou à risque d’interférence ou à de transfert entre l’anglais et l’italien. La présente thèse fournit la première série de preuves neurocognitives d’attrition dans L1. Au travers de différences de traitement dans un groupe de locuteurs natifs ayant vécu dans un environnement exclusivement monolingue jusqu’à l’âge adulte, nos données sont compatibles avec la notion d’une neuroplasticité linguistique persistant au delà d’une période développementale précoce. Nos trois études soulignent le rôle crucial joué par le niveau de maîtrise linguistique dans la modulation des réponses cérébrales liées au langage, et mettent en lumière les parallèles possibles entre l’attrition de L1 et l’acquisition de L2. Nos résultats indiquent que les personnes sujettes à l’attrition font appels à des processus plus conscients et contrôlés dépendant à la fois de facteurs expérimentaux et de circonstances liées à l’expérience faisant partie intégrante du phénomène d’attrition (par exemple une attention accrue, une approche plus prudente ou des remises en question). Le présent travail a donc des conséquences significatives dans la recherche sur la neurocognition du langage et illustre l’utilité d’étudier le phénomène d’attrition en tant que phénomène transitoire entre le traitement de la langue première et celui de la langue seconde

The production of pronouns in Dutch children with developmental language disorders: A comparison between children with SLI, hearing impairment, and Down's syndrome

The production of pronouns in spontaneous language was investigated in three groups of children with Developmental Language Disorders (DLD): children with Specific Language Impairment (SLI), children with hearing impairment (HI), and children with Down's syndrome (DS). The results were compared to the production of pronouns in typically developing children, matched on MLUm. The number of pronouns produced did not differ significantly between the groups. In the order of production of pronouns, more commonalities than differences were found between the three DLD groups and compared to typically developing children. The number of errors in all groups appeared to be very low and all groups showed a significant correlation between the increase in MLU and the production of pronouns. The results are presented in relation to the discussion of whether children with DLD with different aetiologies show a difference in language behaviour

Are Figurative Interpretations of Idioms Directly Retrieved, Compositionally Built, or Both? Evidence from Eye Movement Measures of Reading

Idioms are part of a general class of multiword expressions where the overall interpretation cannot be fully determined through a simple syntactic and semantic (i.e., compositional) analysis of their component words (e.g., kick the bucket, save your skin). Idioms are thus simultaneously amenable to direct retrieval from memory, and to an on-demand compositional analysis, yet it is unclear which processes lead to figurative interpretations of idioms during comprehension. In this eye-tracking study, healthy adults read sentences in their native language that contained idioms, which were followed by figurative- or literal-biased disambiguating sentential information. The results showed that the earliest stages of comprehension are driven by direct retrieval of idiomatic forms, however, later stages of comprehension, after which point the intended meaning of an idiom is known, are driven by both direct retrieval and compositional processing. Of note, at later stages, increased idiom decomposability slowed reading time, suggesting more effortful figurative comprehension. Together, these results are most consistent with multi-determined or hybrid models of idiom processing