ABSTRACT
Recent research on this topic was stimulated by two influential theories o f "cerebral dominance," the Geschwind and Galaburda theory (Geschwind & Behan, 1982; Geschwind & Galaburda, 1985) and Annett 's "right shift" theory (Annett & Ki l shaw, 1983), which have been extensively described, commented, and crit icized elsewhere (Bryden, McManus , & Bulman-Fleming, 1994; M c M a n u s , Shergill , & Bryden, 1993). Despite important differences (e.g., the latter is mainly genetic, the former mainly developmental), both theories suggest links between laterality and cognitive performances in the same directions: a disadvantage o f left-handers in verbal skills, related to nonoptimal development o f the left cerebral hemisphere on the one hand, and enhanced visuospatial skills among left-handers, due to overdeveloped functioning o f the right hemisphere on the other hand. E m - pirical support for the first statement was provided by some studies showing increasing verbal skills, particularly phonology-related, with dextrality (Natsopoulos, Kiosseoglou, Xeromeritou, & Alevriadou, 1998); however such a relation has not always been found (Hardyck, Petrinovich, & Goldman, 1976). Concerning the second statement, that is, increasing "visuospatial" skills wi th sinistrality, the evidence is clearly inconclusive. Annett (1992) found the expected trend, but others found exactly the opposite (Cerone & McKeever , 1999).
