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Processamento de informação semântica categorial e associativa nos hemisférios cerebrais : uma tarefa de decisão lexical com paradigma de priming
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A produção da linguagem e a compreensão são funções dominantes do hemisfério esquerdo, mas foi igualmente sugerido, com base em estudos com doentes com lesão cerebral, que o hemisfério direito também contribui para o processamento da linguagem. Alguns investigadores concordam que o sistema léxico-semântico do hemisfério esquerdo está estruturado de acordo com uma hierarquia de relações lógicas, no entanto não é claro se as capacidades léxico-semânticas rudimentares do hemisfério direito são qualitativamente semelhantes ou dissemelhantes às do hemisfério esquerdo. Um dos métodos que permite investigar as diferenças hemisféricas no processamento de informação semântica envolve a facilitação semântica automática de palavras alvo apresentadas nos campos visuais direito ou esquerdo (paradigma de priming). Estudos que têm abordado este tema têm obtido resultados contraditórios, que parecem depender de diversas variáveis, nomeadamente do tipo de relação semântica, do intervalo entre a apresentação das palavras, do campo visual de apresentação (central ou lateralizado), da proporção de pares relacionados, entre outras. O objectivo deste estudo consistiu em avaliar o contributo de cada um dos hemisférios para o processamento da linguagem, recorrendo ao paradigma de priming hemisférico numa tarefa de decisão lexical envolvendo pares de palavras com relação semântica categorial e associativa. 80 estudantes universitários desempenharam uma tarefa de decisão lexical com resposta go-no go . Apresentámos pares de palavras com relação semântica categorical e associativa: a palavra indicadora durante 150 ms no CVD ou CVE, e 165 ms depois do início desta apresentação aparecia a palavra alvo durante 180 ms. Para além do método de resposta e do SOA curto, utilizámos uma baixa proporção de pares relacionados para manter a tarefa a um nível automático de desempenho, evitando assim a ocorrência de estratégias
Language production and comprehension are functions that are strongly lateralised to the left hemisphere. However, evidence from brain-damaged patients suggests that the right hemisphere also contributes to language processing and possesses a limited vocabulary which enables it to perform simple semantic judgments. While investigators generally agree that the lexical-semantic system in the left hemisphere is structured in accordance with a hierarchy of logical relationships, it is not clear whether the rudimentary lexical-semantic abilities of the right hemisphere are qualitatively similar or dissimilar to those of the language-dominant left hemisphere. One method of investigating hemisphere differences in word-meaning access involves the automatic semantic priming of target words presented to either the left or right visual fields (LVF, RVF). Studies that have addressed the possibility of hemispheric differences in semantic priming effects have yielded contradictory results, which seem to depend on several factors, namely the semantic relationship, SOA, visual field of presentation (central or lateral), and related pairs proportion, among others. In the present work we aimed to evaluate the contribution of each cerebral hemisphere in language processing, using the hemispheric priming paradigm in a lexical decision task with words categorically and associatively related. 80 university students performed a go no go lexical decision task with priming paradigm. Categorically associated word pairs were presented: prime word was presented for 150 ms in the RVF or LVF, and 165 ms after the beginning of this presentation (165 ms SOA) appeared the target word for 180 ms in the RVF or LVF. Besides response method and short SOA, we used as well a low relation proportion in order to maintain performance at a reasonable automatic level, avoiding controlled processing strategies. Priming for RVF-RVF (40 ms) and LVF-RVF (86 ms) was found. These effects, in our study se
Language production and comprehension are functions that are strongly lateralised to the left hemisphere. However, evidence from brain-damaged patients suggests that the right hemisphere also contributes to language processing and possesses a limited vocabulary which enables it to perform simple semantic judgments. While investigators generally agree that the lexical-semantic system in the left hemisphere is structured in accordance with a hierarchy of logical relationships, it is not clear whether the rudimentary lexical-semantic abilities of the right hemisphere are qualitatively similar or dissimilar to those of the language-dominant left hemisphere. One method of investigating hemisphere differences in word-meaning access involves the automatic semantic priming of target words presented to either the left or right visual fields (LVF, RVF). Studies that have addressed the possibility of hemispheric differences in semantic priming effects have yielded contradictory results, which seem to depend on several factors, namely the semantic relationship, SOA, visual field of presentation (central or lateral), and related pairs proportion, among others. In the present work we aimed to evaluate the contribution of each cerebral hemisphere in language processing, using the hemispheric priming paradigm in a lexical decision task with words categorically and associatively related. 80 university students performed a go no go lexical decision task with priming paradigm. Categorically associated word pairs were presented: prime word was presented for 150 ms in the RVF or LVF, and 165 ms after the beginning of this presentation (165 ms SOA) appeared the target word for 180 ms in the RVF or LVF. Besides response method and short SOA, we used as well a low relation proportion in order to maintain performance at a reasonable automatic level, avoiding controlled processing strategies. Priming for RVF-RVF (40 ms) and LVF-RVF (86 ms) was found. These effects, in our study se
Descrição
Tese de mestrado em Neurociências, apresentada à Faculdade de Medicina da Universidade de Lisboa, 2008
Palavras-chave
Processamento de palavras Decisão lexical Hemisférios cerebrais Priming semântico Teses de mestrado - 2008