William Lee Berdel Martin

A cross-cultural comparison of pressures to switch left-hand writing: Brazil versus Canada

Attempts to switch left-hand preferences towards the right side are socialisation practices found in many countries (Perelle & Ehrman, 1994). Although researchers acknowledge that pressures against left-hand use contribute to the cross-cultural fluctuations in the prevalence of left- versus right-hand preference, there has been little systematic cross-cultural study of how these pressures are applied, and who are the major agents applying the pressures to change. Our study explored specific rightward conversion practices and the results of these practices among individuals from two countries. One sample of participants was from a culture categorised as formal, Brazil, and the second sample was from Canada, a nonformal culture (Hofstede, 2001). Researchers have argued that prevalence rates of right-handedness should be higher in cultures that value conformity, called formal cultures, and lower among members of nonformal cultures where conformity pressures are lax (Medland, Perelle, De Monte, & Ehrman, 2004). The socialisation practices used to foster a change from the left to the right side are also predicted to differ in frequency and in kind in formal versus nonformal cultural settings. These cultural differences are assumed to result in differences in success rates of the conversion attempts, with formal cultures producing higher numbers of successfully converted right-handers. Our findings indicate that the formal versus nonformal cultural explanation for cross-cultural fluctuations in the prevalence of hand preference types does not account for the characteristics of the rightward conversion experiences reported by participants in the two groups. We propose that hypotheses concerning the effects of cultural differences on hand preference formation be expanded to include possible biological or genetic variance between groups.

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.

Deriving estimates of contralateral footedness from prevalence rates in samples of Brazilian and non-Brazilian right- and left-handers.

Although footedness is closely associated with handedness, accurate prevalence rates of contralateral footedness in right- and left-handed populations were previously unavailable to researchers studying the relationship between phenotypic and hemispheric asymmetries. We collected preference data from 2081 Brazilian children and adolescents, and relate the prevalence of crossed hand/foot preferences to values reported elsewhere in the literature. In our samples, about 4% of the dextrals and 33% of the sinistrals exhibited a contralateral kicking preference. This is in close agreement with the weighted means from our analysis of 19 papers in the literature, which yields 4.0% left-footed kicking in dextrals and 33.5% right-footed kicking in sinistrals. These values are in marked contrast to the 50% figure for right-footed kicking in sinistrals as given by MacNeilage and colleagues (1988, 1991). Among Brazilians with mixed handedness, there was a substantial increase in incongruent footedness. Male consistent right- and left-handers showed a higher prevalence of cross-footed preferences in their kicking preference than females. The sex difference in dextrals was attributed to a training effect in soccer-related activities, and to a sampling bias in sinistrals.

Mean mortality among Brazilian left- and right-handers: Modification or selective elimination?

Many surveys report a higher incidence of left-handedness in younger than in older cohorts, and explanations for this phenomenon have centred around two rival hypotheses. The modification hypothesis attributes this trend to secular differences in the social tolerance of left-handed preferences, whereas the elimination hypothesis contends that left-handers have a shorter life-span than right-handers do, and hence are infrequent in the population above age 70. In order to evaluate these two hypotheses, data were collected on 513 decedents from kin informants. There were 465 right- and 48 left-handed decedents, including 18 switched sinistrals. Females lived significantly longer than males, and there was a nonsignficant survival advantage for left-handers. Switched left-handers were disproportionately represented among older compared to younger decedents, indicating an historical reduction of sanctions against left-handed writing. These results contradict the survival advantage for right-handers reported by Coren and Halpern (1991), providing evidence more favourable to a cultural conditioning explanation, rather than one emphasising selective mortality.

Footedness across the Age Span among Brazilian Right- and Left-Handers

Previous cross-sectional surveys have reported a decreasing prevalence of left-footedness with increasing age. Bell and Gabbard attributed this pattern to a developmental process wherein the right hemisphere ages earlier than the left, leading to a decline in left-footedness among older individuals. A major flaw in this hypothesis is that age-related data were derived exclusively from right-handed samples. To test the generality of the hypothesis we obtained foot preferences from 1462 right and 172 left-handed Brazilians ranging from 10 to 94 years of age. In only one of the three analyses did dextrals show the predicted age-related decline. Together with accelerating trends towards left-footedness among older males and nonlinear trends among left-handers as a group, these results do not sustain the basic assumptions implicit in the right hemisphere aging hypothesis.

Direitos humanos, atitude institucional e simpatia ideológica em universitários brasileiros

Este trabalho teve como objetivo analisar o posicionamento de universitarios das regioes norte e nordeste do Brasil sobre os direitos humanos (DH) e a relacao desse posicionamento com suas atitudes institucionais, suas simpatias ideologicas e o contexto social em que vivem. Participaram deste estudo 832 universitarios do norte e nordeste brasileiro, de ambos os sexos, que responderam a um questionario, contendo escalas que mediam julgamentos sobre 30 direitos, 15 instituicoes e 10 ideias politicas. Os resultados de uma analise fatorial dos componentes principais sobre os dados referentes aos direitos mostraram a existencia de cinco fatores. Os resultados de uma analise de regressao multipla revelaram a influencia das atitudes institucionais e das simpatias ideologicas sobre o envolvimento com os DH; e a influencia positiva da regiao sobre o direito ao protesto social. Os resultados foram discutidos com base em trabalhos empiricos, realizados a partir do referencial psicossociologico.