Right hemisphericity of Australian aboriginal children: effects of culture, sex, and age on performances of closure and similarities tests.

Right-handed Aboriginal and White Australian urban children were compared in two Greater Sydney areas having substantial Aboriginal subpopulations. The Aboriginal children performed better than their White counterparts on a (right-hemisphere dependent) Closure or Gestalt Completion test, even though they did not do as well on the (left-hemisphere dependent) WISC-R Similarities test. Performance on both tests varied directly with age. Similarities performance as a function of age increased at a greater rate for White than for Aboriginal children. Partition of the Closure items into those containing or not containing one or more parts with elaborated part boundaries showed that items with such elaboration improved with age more than items without elaboration. The sex difference in Closure performance was limited to a male advantage for items without elaborated parts.