Effects of biliteracies on bilingual cognitive functions
Al Rassi, Reham Abdulrahman Ibrahim
Although previous research has examined the effects of bilingualism on cognitive functions, specific biliteracy effects have not been investigated. This thesis looks at the effects of script on three major components of cognitive functions: executive control, mental rotation and hemispheric variance in distinguishing morphological markers. The research is composed of three studies, each focusing on a different aspect of cognitive functions. Study I compare's English monolinguals, Arabic monolinguals, English/Maltese bilinguals and English/Arabic bilinguals. The groups are tested using several executive control tasks (TEA and AX-CPT), concentrating on the fact that, like English, Maltese uses the Latin script, while Arabic uses its own. Maltese has the advantage of sharing a wide range of linguistic characteristics with Arabic, however is the only Semitic language to be written in the Latin script. Results revealed no significant effects of biliteracy on the executive control tasks related to inhibition and switching. In Study II, mental rotation is examined using three Corsi Block Tapping task; Forwards, Backwards and Rotated. The tasks were utilised in order to compare the English, Arabic, and Maltese groups on mental rotation. The results found that both Arabic speaking groups outperformed on the Rotated Corsi, while the English monolinguals and English/ Maltese bilinguals did not. This showed that while script does make a difference for mental rotation, it is an aspect of linguistic diversity, specifically the Arabic script, and not biliteracy. Further comparisons were done on Chinese monolinguals and bilinguals and led to the same conclusion, that the effects found on the mental rotation task are specific to the Arabic script. Further research on late Arabic learners revealed that the mental rotation effect is found after only one year of Arabic study. Study III utilised a visual and an auditory lexical decision task in order to investigate whether there are differences in hemispheric usage between the groups when making linguistic judgments. Previous research had suggested that Semitic languages, employ the use of both hemispheres of the brain in distinguishing morphological markers, whereas English readers rely on the left hemisphere (Ibrahim, Israeli, & Eviatar, 2007). The script differences between Maltese and Arabic helped determine whether the previous results were linked to the directionality of the script or the morphemes themselves. Results reiterated that both Semitic languages, Maltese and Arabic, showed no hemispheric preference in Maltese and Arabic respectively, however both groups and the English monolinguals showed a left hemispheric preference in English. The three studies report unique finding on an aspect of bilingualism that has not been examined, biliteracy. While the results did not show biliteracy effects on cognitive functions, linguistic diversity was shown to have an effect on both mental rotation and hemispheric variance in distinguishing morphological markers.