EN
In typical right-handers, the processing of tool-related information is lateralized to the left hemisphere. Yet, the hemispheric dominance for tools in left-handers is still debated. Since visual half-field (VHF) paradigms provide a reliable measure of cerebral asymmetries, left vs. right hemisphere advantage for man-made object categorization was studied in 17 left-handers (9 women, mean age = 23 years) using a VHF test. The task was to decide whether one of the two bilaterally presented line drawings depicted a tool or non-tool. Given a higher incidence of atypical organization of functions in sinistrals, participants were divided into 2 groups, showing either right or left visual field advantage irrespective of the target objects. Nonetheless, significant effects of visual half-field were found exclusively for tool discrimination. Namely, subjects with the putative typical organization of functions (n=9) showed significantly faster response times for tools correctly categorized in the right visual field (i.e. processed in the left hemisphere) whereas those with atypically organized functions (n=8) responded faster to tools processed in the left visual field (right hemisphere). None of the groups showed any dominance for non-tools. The results indicate that even a simple visual processing of tools can vary significantly across left-handers. It remains to be seen if the observed patterns are linked to language dominance.