Language laterality in English/Welsh bilinguals: Language-acquisitional and language-specific factors in the development of lateralisation

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.

Development of cerebral lateralisation for recognition of emotions in chimeric faces in children aged 5 to 11

In contrast to research into the development of language laterality, there has been relatively little research into the development of lateralisation of emotional processing. If language lateralisation begins in childhood and is complete by puberty (Lenneberg, 1967) it seems reasonable that the lateralisation of the perception of emotions might also occur during this period. In this study a split field chimeric faces test using the six universal facial expressions proposed by Ekman and Friesen (1971), an emotion in the eyes test, and a situational cartoon test were administered to three groups of children aged 5/6, 7/8, and 10/11. No overall hemispace advantage was seen for the 5/6-year-old group, but by the age of 10/11 a clear left hemispace advantage (right hemisphere) was found for all six emotions. Such a pattern is comparable to a previous study that made use of adults on this task (Workman, Peters, & Taylor, 2000b). Moreover, a significant positive correlation between a child's ability to recognise emotions in cartoon situations and their left hemispatial advantage score was uncovered. Finally, a significant positive correlation between a child's ability to recognise emotions in the eyes of others and their left hemispatial advantage score was also uncovered. These findings are taken as evidence that there may be a relationship between the development of emotional processing in the right hemisphere and a child's emerging ability to perceive or attend to the emotional states of others. Results are discussed in relation to the child's development of a theory of mind.

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).