Patterns of handedness and footedness in switched and nonswitched Brazilian left-handers: cultural effects on the development of lateral preferences.

In Western societies most left-handers who are pressured to write with the right hand resist the pressure. Searleman and Porac (2001, 2003) studied North American participants and proposed that mixed left-handers, more so than consistent left-handers, would be likely to successfully acquire right-handed writing skills on a long-term basis. In accordance with their two-phenotype hypothesis, the majority of switched left-handers (SLH) in their studies exhibited right-sided asymmetries on other handedness tasks such as throwing, and, in addition, tended to be right-footed. In order to ascertain whether this hypothesis had cross-cultural generality, handedness and footedness data were obtained from 3,716 Brazilian participants. Of the 650 left-handed participants, 62 (9.5%) had successfully switched to right-handed writing. Analyses of preference patterns revealed that the majority of the SLH were left-handed for other tasks, including throwing, and also preferred to kick soccer penalties with their left foot. The results were supportive of a variable rather than a two-phenotype model relating hand preference consistency to successful rightward conversion of the writing hand. The cross-cultural differences found between North American and Brazilian SLH were attributed to divergent socialization training effects and the development of different value orientations in the North versus South American cultural milieu.