Master of Science / Department of Psychology / Richard J. Harris / The present study examined the effects of discourse context information on English Monolinguals' and Spanish-English Bilinguals' ability to 1) translate Spanish and Finnish vocabulary words and 2) comprehend inferential and factual comprehension questions based on language-mixed prose. Language-mixed (i.e., codeswitched) prose varied in the number of foreign words presented in each sentence (i.e., 0, 1, 2, or 3 words per sentence). Results indicated that Monolinguals and Bilinguals' ability to translate Finnish words from pre-test to post-test increased due to their use of contextual information as an aid in translation. Furthermore, Monolinguals' translation accuracy increased from pre-test to post-test when tested on Spanish vocabulary words, but Bilinguals' translation difference scores did not increase from pre-test to post-test, due to their high prior knowledge of Spanish. Monolinguals and Bilinguals' comprehension accuracy was high throughout all conditions, even when tested on material conveyed by Finnish and Spanish words. Results from the study suggest that the use of language-mixed prose does not necessarily impair comprehension or translation ability for Monolinguals or Bilinguals, but in fact provides the context to help translate foreign vocabulary words and draw pragmatic inferences and factual information from text. The findings from this study are of importance in suggesting that, through the use of written contextual information, it is possible to learn basic foreign language vocabulary. Implications for foreign language learning, language-mixing as a mode of communication, and models of language acquisition and lexical access are discussed.

Thesis (PhD)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: This study investigates the effect of the increased use of a second language (L2) (English) as language of teaching and learning on the bilingual individual in a specific bilingual higher education context. The specific interest is in the development of conceptual fluency, and the role that bilingualism and the increased exposure to an L2 in a teaching and learning context plays in such development. In order to serve the interest of the study, the theoretical framework includes theories developed in language and cognition, bilingualism and cross-linguistic influence. The theoretical stance that is taken in this thesis is one that: recognises that bilingual individuals cannot be expected to exhibit the same kind of linguistic and conceptual knowledge as monolinguals, investigates the possibility that language can affect certain aspects of cognition, acknowledges that bilingual individuals themselves can contribute to the knowledge about the bilingual mind. The participants in the study are L1 speakers of Afrikaans who finished their secondary schooling in Afrikaans. At university they are increasingly exposed to more English as language of teaching and learning than in previous formal education. The effects of the increased use of English on conceptual fluency, academic achievement and self-perception of language proficiency were investigated. The study used university records, language tests and interviews to collect data. No concrete evidence could be found that English has a significantly positive or negative effect on 'conceptual fluency', academic achievement or self-perception of language proficiency. The study however provided valuable information about how bilinguals use the languages they have in their repertoires. The findings from the study suggest that increased exposure to an L2 leads to a unique form of language competence. This 'multi-competence' enables the participants in the study to use both languages in the understanding and learning of concepts in their respective fields of study. Thus this dissertation provides evidence that bilinguals can transfer knowledge and skills between the languages they know. Theories developed by Cook (1999, 2003) and Jarvis and Pavlenko (2008), that suggest transfer is bidirectional, is partly supported by the findings of the study. The study has various implications for the field of bilingualism in education. It illustrates how a multilingual context such as the one we have in South Africa complicates the use of certain methodologies and theoretical frameworks. This also means that models of bilingual education designed elsewhere cannot be implemented in the South African context without considered modification. / AFRIKAANSE OPSOMMING : Hierdie studie het die effek van die toenemende gebruik van Engels (tweede taal) as medium van onderrig, op die tweetalige individu in 'n spesifieke tweetalige hoër onderwys konteks probeer peil. Die spesifieke belangstelling is in die ontwikkeling van konseptuele vlotheid en die rol wat tweetaligheid en die toenemende blootstelling aan 'n tweede taal (T2) in 'n onderrig en leer konteks speel in sodanige ontwikkeling. Om die belangstelling van die studie te dien, sluit die teoretiese raamwerk teorieë oor taal en kognitiewe vaardighede, tweetaligheid, en kruislinguistiese taal invloed in. Die teoretiese standpunt wat in die tesis geneem word, is een wat: erken dat tweetalige individue nie noodwendig dieselfde talige en konseptuele kennis as eentaliges vertoon nie, die moontlikheid ondersoek dat taal sekere aspekte van kognisie kan beïnvloed, en erken dat tweetalige individue kan bydra tot kennis oor die tweetalige denke. Die deelnemers aan die studie is eerstetaal sprekers van Afrikaans wat hulle sekondêre skoolloopbaan in Afrikaans voltooi het. In hulle universiteitsopleiding word hulle toenemend blootgestel aan meer Engels as taal van leer en onderrig as in hul vorige formele opleiding. Spesifiek is die effek van die gebruik van Engels op die Afrikaanse 'konsepsuele vlotheid', algehele akademiese prestasie en self-persepsie ondersoek. Die studie het universiteitsrekords, taaltoetse en onderhoude gebruik om data in te samel. Geen konkrete bewyse kon gevind word dat die gebruik van Engels, enige van die aspekte beduidend negatief of positief beïnvloed nie. Die studie het egter waardevolle inligting verskaf oor hoe tweetaliges die tale tot hul beskikking gebruik, en het ook bewyse gelewer dat toenemende blootstelling aan die tweede taal, 'n unieke vorm van taalvaardigheid tot gevolg het. Hierdie "multi-vaardigheid" het tot gevolg dat die deelnemers aan die studie toenemend beide tale gebruik in die leer en verstaan van konsepte in hul onderskeie studievelde. Die studie het ook ondersteuning gebied dat tweetaliges kennis en vaardighede kan oordra tussen die tale wat hulle ken. Teorieë wat deur Cook (1999, 2003) en Jarvis en Pavlenko (2008) ontwikkel is, wat voorstel dat oordrag bi-direksioneel is, word dus gedeeltelik ondersteun deur die studie. Die studie het verskeie implikasies vir die terrein van tweetaligheid in opvoedkunde. Dit illustreer hoe 'n veeltalige konteks soos ons dit in Suid-Afrika vind, die gebruik van sekere metodologieë en teoretiese raamwerke kompliseer. Dit beteken ook dat huidige modelle van tweetalige onderrig wat elders ontwikkel is nie sonder meer gebruik kan word in die Suid-Afrikaanse konteks sonder om dit aan te pas nie.

Second language acquisition has proven to impact the brain in many ways. Studies have shown a distinct difference between the monolingual and the bilingual brain. These structural differences have included an observable increase in cortical thickness in bilingual individuals when compared to monolinguals. This is a significant observation since many neurological diseases and impairments have been connected to a decrease in cortical thickness. However, previous studies have focused solely on bilinguals who had acquired their second language early on in life. These studies have failed to focus on the potential impact that could be observed on the cortical thickness of individuals who acquire a language after the age of 40. This study focused on monolingual students 40 years and older, who participated in an entry level university level Spanish course and examined how their brains structurally changed after a three-month course. These results were compared to a group of adults not participating in a language course who acted as a control group. This was achieved through MRI imaging of all the participants' brains and measuring any changes in their cortical thickness. Upon completing the second round of MRI imaging, the comparison of the pre and post MRI scans yielded an observable difference between the experimental group who had participated in the Spanish course and the control group. However, these differences did not prove to be significant and should be viewed as exploratory. Future research opportunities should entail studies with a longer duration combined with a curriculum better suited to this age group.

L'objectif de cette thèse est d'étudier le développement du système lexico-sémantique chez les enfants monolingues et bilingues. La question posée est la suivante : quand et comment les significations des mots commencent à être reliées entre elles et à s'intégrer dans un système sémantique interconnecté. Dans un premier temps, trois études ont été menées chez des enfants monolingues français. L'Etude 1, a pour but d'observer si les mots sont organisés selon des liens taxonomiques (e.g., cochon - cheval). L'Etude 2 explore si l'effet d'amorçage sémantique est sous-tendu par des mécanismes cognitifs, comme les processus d'activation automatique et contrôlé. Puis enfin, l'Etude 3 observe si les mots sont organisés en fonction de leur distance de similarité sémantique (e.g., vache - mouton versus vache - cerf). Dans un deuxième temps, deux études ont été conduites chez des enfants apprenant deux langues simultanément. L'Etude 4 vise à déterminer si les mots sont taxonomiquement liés dans chacune des langues. L'Etude 5 explore si les mots présentés dans une langue activent leurs représentations sémantiques dans l'autre langue et vice versa. Dans le but de répondre à ces questions, le traitement lexico-sémantique a été étudié en utilisant deux techniques : l'eye-tracking et les potentiels évoqués (PEs). Ces deux techniques enregistrent lors de la présentation des mots des réponses comportementales (Etude 3) et neuronales (Etude 1, 2, 4 et 5) de haute résolution temporelle. Les Etudes 1 et 2 montrent que chez les monolingues les mots sont liés taxonomiquement à l'âge de 18 et 24 mois. Durant le développement du langage, les deux processus d'activation automatique et contrôlé sont impliqués dans le traitement des mots (Etude 2). L'Etude 3 montre qu'à 24 mois, les mots sont organisés dans le système lexico-sémantique en développement selon la distance des similarités sémantiques. L'Etude 4 montre que chez les enfants bilingues, le traitement sémantique ne diffère pas selon les deux langues, mais la topographie des PEs varie selon la langue traitée. L'Etude 5 montre que les mots présentés dans une langue activent leurs représentations sémantiques dans la deuxième langue et vice versa. Toutefois, la topographie des PEs est modulée selon la direction de traduction. Ces résultats suggèrent que l'acquisition de deux langues, bien qu'elle soit très précoce, requière deux ressources neuronales bien distinctes, sous-tendant ainsi le traitement lexico-sémantique des langues dominante et non-dominante. / The present doctoral research explored the developing lexical-semantic system in monolingual and bilingual toddlers. The question of how and when word meanings are first related to each other and become integrated into an interconnected semantic system was investigated. Three studies were conducted with monolingual French learning children which aimed at exploring how words are organized, that is, according to taxonomic relationships (e.g., pig - horse) and to semantic similarity distances between words (e.g., cow - sheep versus cow - deer), and whether cognitive mechanisms, such as automatic activation and controlled processes, underlie priming effects. An additional two studies conducted with children learning two languages simultaneously, aimed at determining, first, whether taxonomically related word meanings, in each of the two languages, are processed in a similar manner. The second goal was to explore whether words presented in one language activate words in another language, and vice versa. In an attempt to answer these questions, lexical-semantic processing was explored by two techniques: eye-tracking and event-related potentials (ERPs) techniques. Both techniques provide high temporal resolution measures of word processing but differ in terms of responses. Eye-movement measurements (Study III) reflect looking preferences in response to spoken words and their time-course, whereas ERPs reflect implicit brain responses and their activity patterns (Study I, II, IV, and V). Study I and II revealed that words are taxonomically organized at 18 and 24-month-olds. Both automatic and controlled processes were shown to be involved in word processing during language development (Study II). Study III revealed that at 24-month-olds, categorical and feature overlap between items underpin the developing lexical-semantic system. That is, lexical-items in each semantic category are organized according to graded similarity distances. Productive vocabulary skills influenced word recognition and were related to underlying cognitive mechanisms. Study IV revealed no differences in terms of semantic processing in the bilinguals¿ two languages, but the ERP distribution across the scalp varied according to the language being processed. Study V showed that words presented in one language activate their semantic representations in the second language and the other way around. The distribution of the ERPs depended, however, on the direction of translation. The results suggest that even early dual language experience yields distinct neural resources underlying lexical-semantic processing in the dominant and non-dominant languages during language acquisition.

L'objectif de cette thèse est d'étudier le développement du système lexico-sémantique chez les enfants monolingues et bilingues. La question posée est la suivante : quand et comment les significations des mots commencent à être reliées entre elles et à s'intégrer dans un système sémantique interconnecté. Dans un premier temps, trois études ont été menées chez des enfants monolingues français. L'Etude 1, a pour but d'observer si les mots sont organisés selon des liens taxonomiques (e.g., cochon - cheval). L'Etude 2 explore si l'effet d'amorçage sémantique est sous-tendu par des mécanismes cognitifs, comme les processus d'activation automatique et contrôlé. Puis enfin, l'Etude 3 observe si les mots sont organisés en fonction de leur distance de similarité sémantique (e.g., vache - mouton versus vache - cerf). Dans un deuxième temps, deux études ont été conduites chez des enfants apprenant deux langues simultanément. L'Etude 4 vise à déterminer si les mots sont taxonomiquement liés dans chacune des langues. L'Etude 5 explore si les mots présentés dans une langue activent leurs représentations sémantiques dans l'autre langue et vice versa. Dans le but de répondre à ces questions, le traitement lexico-sémantique a été étudié en utilisant deux techniques : l'eye-tracking et les potentiels évoqués (PEs). Ces deux techniques enregistrent lors de la présentation des mots des réponses comportementales (Etude 3) et neuronales (Etude 1, 2, 4 et 5) de haute résolution temporelle. Les Etudes 1 et 2 montrent que chez les monolingues les mots sont liés taxonomiquement à l'âge de 18 et 24 mois. Durant le développement du langage, les deux processus d'activation automatique et contrôlé sont impliqués dans le traitement des mots (Etude 2). L'Etude 3 montre qu'à 24 mois, les mots sont organisés dans le système lexico-sémantique en développement selon la distance des similarités sémantiques. L'Etude 4 montre que chez les enfants bilingues, le traitement sémantique ne diffère pas selon les deux langues, mais la topographie des PEs varie selon la langue traitée. L'Etude 5 montre que les mots présentés dans une langue activent leurs représentations sémantiques dans la deuxième langue et vice versa. Toutefois, la topographie des PEs est modulée selon la direction de traduction. Ces résultats suggèrent que l'acquisition de deux langues, bien qu'elle soit très précoce, requière deux ressources neuronales bien distinctes, sous-tendant ainsi le traitement lexico-sémantique des langues dominante et non-dominante. / The present doctoral research explored the developing lexical-semantic system in monolingual and bilingual toddlers. The question of how and when word meanings are first related to each other and become integrated into an interconnected semantic system was investigated. Three studies were conducted with monolingual French learning children which aimed at exploring how words are organized, that is, according to taxonomic relationships (e.g., pig - horse) and to semantic similarity distances between words (e.g., cow - sheep versus cow - deer), and whether cognitive mechanisms, such as automatic activation and controlled processes, underlie priming effects. An additional two studies conducted with children learning two languages simultaneously, aimed at determining, first, whether taxonomically related word meanings, in each of the two languages, are processed in a similar manner. The second goal was to explore whether words presented in one language activate words in another language, and vice versa. In an attempt to answer these questions, lexical-semantic processing was explored by two techniques: eye-tracking and event-related potentials (ERPs) techniques. Both techniques provide high temporal resolution measures of word processing but differ in terms of responses. Eye-movement measurements (Study III) reflect looking preferences in response to spoken words and their time-course, whereas ERPs reflect implicit brain responses and their activity patterns (Study I, II, IV, and V). Study I and II revealed that words are taxonomically organized at 18 and 24-month-olds. Both automatic and controlled processes were shown to be involved in word processing during language development (Study II). Study III revealed that at 24-month-olds, categorical and feature overlap between items underpin the developing lexical-semantic system. That is, lexical-items in each semantic category are organized according to graded similarity distances. Productive vocabulary skills influenced word recognition and were related to underlying cognitive mechanisms. Study IV revealed no differences in terms of semantic processing in the bilinguals¿ two languages, but the ERP distribution across the scalp varied according to the language being processed. Study V showed that words presented in one language activate their semantic representations in the second language and the other way around. The distribution of the ERPs depended, however, on the direction of translation. The results suggest that even early dual language experience yields distinct neural resources underlying lexical-semantic processing in the dominant and non-dominant languages during language acquisition.

L'objectif de cette thèse est d'étudier le développement du système lexico-sémantique chez les enfants monolingues et bilingues. La question posée est la suivante : quand et comment les significations des mots commencent à être reliées entre elles et à s'intégrer dans un système sémantique interconnecté. Dans un premier temps, trois études ont été menées chez des enfants monolingues français. L'Etude 1, a pour but d'observer si les mots sont organisés selon des liens taxonomiques (e.g., cochon - cheval). L'Etude 2 explore si l'effet d'amorçage sémantique est sous-tendu par des mécanismes cognitifs, comme les processus d'activation automatique et contrôlé. Puis enfin, l'Etude 3 observe si les mots sont organisés en fonction de leur distance de similarité sémantique (e.g., vache - mouton versus vache - cerf). Dans un deuxième temps, deux études ont été conduites chez des enfants apprenant deux langues simultanément. L'Etude 4 vise à déterminer si les mots sont taxonomiquement liés dans chacune des langues. L'Etude 5 explore si les mots présentés dans une langue activent leurs représentations sémantiques dans l'autre langue et vice versa. Dans le but de répondre à ces questions, le traitement lexico-sémantique a été étudié en utilisant deux techniques : l'eye-tracking et les potentiels évoqués (PEs). Ces deux techniques enregistrent lors de la présentation des mots des réponses comportementales (Etude 3) et neuronales (Etude 1, 2, 4 et 5) de haute résolution temporelle. Les Etudes 1 et 2 montrent que chez les monolingues les mots sont liés taxonomiquement à l'âge de 18 et 24 mois. Durant le développement du langage, les deux processus d'activation automatique et contrôlé sont impliqués dans le traitement des mots (Etude 2). L'Etude 3 montre qu'à 24 mois, les mots sont organisés dans le système lexico-sémantique en développement selon la distance des similarités sémantiques. L'Etude 4 montre que chez les enfants bilingues, le traitement sémantique ne diffère pas selon les deux langues, mais la topographie des PEs varie selon la langue traitée. L'Etude 5 montre que les mots présentés dans une langue activent leurs représentations sémantiques dans la deuxième langue et vice versa. Toutefois, la topographie des PEs est modulée selon la direction de traduction. Ces résultats suggèrent que l'acquisition de deux langues, bien qu'elle soit très précoce, requière deux ressources neuronales bien distinctes, sous-tendant ainsi le traitement lexico-sémantique des langues dominante et non-dominante. / The present doctoral research explored the developing lexical-semantic system in monolingual and bilingual toddlers. The question of how and when word meanings are first related to each other and become integrated into an interconnected semantic system was investigated. Three studies were conducted with monolingual French learning children which aimed at exploring how words are organized, that is, according to taxonomic relationships (e.g., pig - horse) and to semantic similarity distances between words (e.g., cow - sheep versus cow - deer), and whether cognitive mechanisms, such as automatic activation and controlled processes, underlie priming effects. An additional two studies conducted with children learning two languages simultaneously, aimed at determining, first, whether taxonomically related word meanings, in each of the two languages, are processed in a similar manner. The second goal was to explore whether words presented in one language activate words in another language, and vice versa. In an attempt to answer these questions, lexical-semantic processing was explored by two techniques: eye-tracking and event-related potentials (ERPs) techniques. Both techniques provide high temporal resolution measures of word processing but differ in terms of responses. Eye-movement measurements (Study III) reflect looking preferences in response to spoken words and their time-course, whereas ERPs reflect implicit brain responses and their activity patterns (Study I, II, IV, and V). Study I and II revealed that words are taxonomically organized at 18 and 24-month-olds. Both automatic and controlled processes were shown to be involved in word processing during language development (Study II). Study III revealed that at 24-month-olds, categorical and feature overlap between items underpin the developing lexical-semantic system. That is, lexical-items in each semantic category are organized according to graded similarity distances. Productive vocabulary skills influenced word recognition and were related to underlying cognitive mechanisms. Study IV revealed no differences in terms of semantic processing in the bilinguals¿ two languages, but the ERP distribution across the scalp varied according to the language being processed. Study V showed that words presented in one language activate their semantic representations in the second language and the other way around. The distribution of the ERPs depended, however, on the direction of translation. The results suggest that even early dual language experience yields distinct neural resources underlying lexical-semantic processing in the dominant and non-dominant languages during language acquisition.

“Linguistic relativity” has been studied for a long time. Many empirical studies have been conducted on cross-linguistic differences to find support for the influence of language on thought. This study proposes viewpoint (defined as the point from which the conceptualizer sees and construes the event) as a cross-linguistic difference, and explores whether the linguistic constraint and preference of subjective/objective construal can affect one’s cognitive activity as viewpoint. As Japanese is a subjectivity-prominent language whereas Swedish is not, data elicited from monolingual adolescences (aged 12-16) in Japan and Sweden were compared. A set of tasks which consisted of non-verbal tasks (scene-visualisation) and verbal tasks (narrative of comic strips) was performed in order to elicit the participants’ viewpoints. The same set of tasks was assigned to simultaneous Swedish-Japanese bilingual adolescences in Sweden. The bilinguals took the set of non-verbal and verbal tasks twice, once in Swedish and once in Japanese. The results demonstrated a clear difference between the monolingual groups both in the non-verbal and verbal tasks. The Japanese monolinguals showed a higher preference for subjective viewpoint. The bilinguals’ viewpoint preference had a tendency to fall between that of monolinguals of both languages. This finding indicates that the bilinguals’ viewpoint preference may be influenced by both languages. This study demonstrates for the first time that the speaker’s viewpoint can be affected not only in verbal tasks but also in non-verbal tasks. The findings suggest that a language may influence the speaker’s way of construing events. It is also implied that the influences from different languages in bilinguals can be bidirectional. However, the influence does not seem to be all or nothing. Regardless of the language, one’s event construal is more or less the same. Nevertheless, the findings indicate that the linguistic subjectivity in a language tends to counteract the universal construal. / Språkrelativitet (Linguistic relativity) har studerats under lång tid. Många empiriska studier har studerat om och i så fall hur språk påverkar tänkandet och eventuella skillnader mellan olika språk. Denna studie föreslår perspektivpreferens för att beskriva ur vilket perspektiv en berättare återger skeenden. Studien utforskar om ett språks lingvistiska begränsningar och preferens för subjektiva/objektiva tolkningar av skeenden påverkar personers kognitiva aktivitet som val av perspektiv. Japanska är ett tydligt subjektivt framträdande språk medan svenskan inte är det. Därför jämfördes data från enspråkiga ungdomar (12-16 år gamla) i Japan och i Sverige. För att klarlägga deltagarnas perspektivpreferens genomfördes två delstudier, dels en icke-verbal studie (en scenvisualisering) och dels en verbal studie (ett återberättande av tecknade serier). Samma delstudier genomfördes också till simultant svensk-japanska tvåspråkiga ungdomar i Sverige. De tvåspråkiga deltagarna gjorde de verbala och icke-verbala delstudierna i två omgångar, en gång på svenska och en gång på japanska. Resultatet visade en klar skillnad mellan de enspråkiga grupperna, både i den icke-verbala och verbala delstudien. De japanska enspråkiga deltagarna visade högre preferens för subjektiva tolkningar. De tvåspråkiga deltagarnas perspektivpreferens hade en tendens att komma mellan de enspråkiga deltagarnas preferenser. Detta indikerar att de tvåspråkigas val av perspektiv påverkades av deras tvåspråkighet. Studien visar för första gången att berättarens val av perspektiv kan påverkas inte bara i verbala uppgifter utan också i icke-verbala uppgifter. Resultaten från studien indikerar att ett språk kan påverka en berättares sätt att tolka händelser, och att påverkan från de olika språken hos tvåspråkiga kan vara dubbelriktad. Oberoende av språk återges skeenden på ett likartat sätt. Studien indikerar emellertid att lingvistisk subjektivitet i ett språk tenderar att motverka ett universellt återgivande av perspektiv.

This dissertation investigates how cognates are organized in the bilingual mental lexicon and examines whether orthography in one language, via phonological representations, influences the processing of cognates and false friends in the other language. In light of the framework of two well-known models of bilingual visual word recognition, the Bilingual Interactive Activation (BIA) and the Bilingual Interactive Activation Plus (BIA+), the premise is that there is activation from orthography to phonology across a bilingual’s two languages and that this activation is modulated by the degree of orthographic and phonological code overlap. Two objective metrics were used to assess crosslinguistic similarity of Portuguese-English cognates and false friends that were selected for a cross-language lexical decision task with masked priming. Dynamic time warping (DTW), an algorithm that was originally conceived to compare different speech patterns in automatic speech recognition and to measure acoustic similarity between two time-dependent sequences, was used to compute crosslinguistic phonological similarity. The Normalized Levenshtein Distance (NLD), an algorithm that calculates the minimum number of single-character insertions, deletions or substitutions required to change one word into another and normalizes the result by their lengths, was used to compute crosslinguistic orthographic similarity. Portuguese-English bilinguals who acquired their second language after reaching puberty, and English functional monolinguals who grew up speaking primarily English were recruited to participate in the experimental task. Based on collected reaction time and accuracy data, mixed-effects models analyses are used to estimate the individual effects of crosslinguistic orthographic, phonological and semantic similarity and the role each of them, along with English proficiency, word frequency and length play in the organization of the Portuguese-English bilingual mental lexicon.