Cerebral organization in adult second language acquisition: is the right hemisphere more involved?

Resolução temporal e potenciais corticais em diferentes níveis de proficiência da língua inglesa

RESUMO Objetivos: investigar e comparar as habilidades auditivas entre normo-ouvintes bilíngues estudantes de diferentes níveis de proficiência do inglês por meio de teste comportamental e eletrofisiológico. Métodos: este estudo tem caráter descritivo, quantitativo e transversal. A amostra foi composta por 39 sujeitos (alunos de escolas de idiomas: 13 no nível avançado (GA); 13 no nível intermediário (GI); 13 no nível básico (GB)), com idade entre 18 a 35 anos, limiares auditivos tonais dentro dos limites da normalidade e sem queixas de habilidades de processamento auditivo. Foram submetidos aos testes comportamentais: teste de detecção de gap (RGDT); e ao teste eletrofisiológico potencial evocado auditivo de longa latência (PEALL), com estímulos verbais (sílabas /ba/ - frequente - e /di/ - raro) Resultados: verificou-se diferença estatisticamente significante entre as orelhas para: o GB, para a amplitude de N1 e P2, com maiores valores para a orelha esquerda; o GI, para a amplitude de P1, N1 e P2, com maiores valores para a orelha esquerda, o GA, para a latência do componente N1, com maiores valores para a orelha esquerda, e, para as amplitudes dos componentes P2, N2 e P3, com maiores valores para a orelha esquerda. Entre os grupos, o teste RGDT mostrou menores valores para GA e para latência do componente N1, com maiores valores para o GB. Conclusões: pode-se concluir que o nível de proficiência avançado da língua inglesa estimula a velocidade de conexões neurais desencadeando a ocorrência mais rápida do potencial N1, assim a habilidade de resolução temporal é significantemente melhor à medida que o tempo de estudo aumenta.

Visual laterality effects in readers of a deep and a shallow orthography

Using a tachistoscopic split-field paradigm, hemifield asymmetry for single word recognition was examined in monolingual English speakers and in fluent bilingual English-Welsh speakers. A robust right hemifield advantage was found for both groups and both languages. Among bilinguals, the laterality index was significantly greater for Welsh than for English, supporting previous findings. The magnitude of the laterality index was unaffected by which language was learned first (Welsh or English) and by the age of acquisition (before or after 5-6years old) of the second language. However, among bilinguals there was a significant difference in the laterality index for Welsh words compared with English words for those participants brought up in a predominantly Welsh-speaking environment, but not for those brought up in a predominantly English-speaking or dual-language environment. We attribute our results to the difference in orthographic depth between Welsh and English. and argue that the transparency of Welsh favours adoption of a left-hemisphere based phonological decoding strategy in reading. Such a strategy is not necessarily used exclusively by readers of Welsh, but is encouraged by regular exposure to the Welsh language on a day-to-day basis.

Laterality and language experience

A meta-analysis was conducted on studies that examined hemispheric functional asymmetry for language in brain-intact monolingual and bilingual adults. Data from 23 laterality studies that directly compared bilingual and monolingual speakers on the same language were analysed (n = 1234). Variables examined were language experience (monolingual, bilingual), experimental paradigm (dichotic listening, visual hemifield presentation, and dual task) and, among bilinguals, the influence of second language proficiency (proficient vs nonproficient) and onset of bilingualism (early, or before age 6; and late, or after age 6). Overall, monolinguals and late bilinguals showed reliable left hemisphere dominance, while early bilinguals showed reliable bilateral hemispheric involvement. Within bilinguals, there was no reliable effect of language proficiency when age of L2 acquisition was controlled. The findings indicate that early learning of one vs. two languages predicts divergent patterns of cerebral language lateralisation in adulthood.

The bilingual Loch Ness Monster raises its non-asymmetric head again-or, why bother with such cumbersome notions as validity and reliability? Comments on Evans et al. (2000)

All of the experimental studies of the past 25 years combined and the meta-analyses of their findings have not advanced our knowledge of the lateralization of language in bilingual speakers one bit. We are left with a clutter of inherently uninterpretable contradictory results. Successive studies do not contribute a single brick to the edifice or a single piece to the puzzle-only more confusion. study is no exception. So far, there has been no demonstration of the validity of any experimental paradigm claiming to measure degree of language laterality in bilingual speakers. Experimentation is pointless unless the nature of what is alleged to be lateralized is clearly defined and the validity of the measures employed has been established. Because of the lack of validity of the paradigms used in bilingual laterality studies, experiments and meta-analyses of their findings cannot have any scientific significance. Like their predecessors, Evans et al. pay lip service to a number of methodological problems, but ignore their implications and simply carry on anyway. The authors ought to demonstrate, rather than assume, that degree of visual half-field advantage for single words corresponds to degree of lateralization of any component of language (even if only of words).

Cross-cultural differences in laterality

Twenty Hebrew speaking subjects identified sets of six digits paired with environmental sounds. Comparison of their performance with those of Japanese- and English-speakers (Hatta & Dimond, 1981) showed that while there were no group differences in overall level of performance, right ear superiority effects were larger for the English- than for the Hebrew- and Japanese-speakers. The data can be interpreted as reflecting the effects of either the linguistic properties of the native language, or of the sequence of language acquisition.

The implications of bilingualism in the study and treatment of psychiatric disorders: a review

This review of the data on bilinguals in relation to hypnosis, psychotherapy and psychotic disorders presents evidence for the bilateral representation of language in the cerebral hemispheres of bilinguals, and outlines possible links between the neuropsychology of psychotic disorders and the lateralization of language in these patients. The relationship between affective states and the retrieval of memories and language is also explored.