Navegando por Assunto "Destrismo e sinistrismo"

Agora exibindo 1 - 2 de 2

Acesso aberto (Open Access)
Desempenho na grafia e na direção grafológica em função da postura e da dominância manual em destros e canhotos em famílias de renda baixa e média
(Universidade Federal do Pará, 2007-04-17) SILVEIRA, Francisca Morais da; MARTIN, William Lee Berdel; http://lattes.cnpq.br/8591034699611752
There are three distinct theories that seek to explain the origin of the inverted hand posture (IHP) in left-handers. McKeevers genetic model assumes that the trait is sex-linked, tied to maternal transmission via the X-chromosome, which accounts for the higher prevalence of IHP among males. According to the pathological model, the IHP stems from neuropathological factors, whereas the technical adaptation theory views it as a manual adaptation for coping with abductive demands implicit in the Roman writing system. Many adherents of the latter theory regard the posture as maladaptive, leading to physical problems and illegible script; they recommend that the noninverted posture be used. A previous study was conducted among 96 lower-income adolescents, 48 left- and 48 righthanded, subdivided by sex and writing posture. This investigation extended that study by evaluating an additional 106 students from middle income families, 64 right- and 66 lefthanders. The main objectives were to ascertain whether the IHP was associated with physical problems, birth complications, different patterns of graphological direction and inferior calligraphic performance, as well as to verify whether these characteristics varied with socioeconomic status. As a whole, the findings showed no relationship between IHP, physical and pre-natal problems. On the graphological stimuli, IHP left-handers, more so than noninverters and dextrals tended to draw horizontal lines right-to left; however on other drawing tasks they did not differ from the other groups. On the cursive and printed writing task, females consistently outperformed males. Left-handers committed more errors when printing, but not when In general writing cursively. Response time was the only dependent variable related to socioeconomic status: Middle class students wrote and printed sentences faster than lower-class students. In general, these results do not support the contention that the IHP causes physical problems or inferior calligraphic performance, and thus do not justify attempts to oblige left-handers to adopt the noninverted posture.
Acesso aberto (Open Access)
Os efeitos da idade sobre o padrão de assimetrias táteis, visuais e hemiespaciais em destros e canhotos
(Universidade Federal do Pará, 2008-06) LIMA, Fábio Djan Oliveira de; MARTIN, William Lee Berdel; http://lattes.cnpq.br/8591034699611752
When bisecting horizontal lines, normal individuals tend to err leftwards of the true center, or zero point, a phenomenon known as "pseudonegligence. Previous clinical investigations indicated that lestions in the inferior portion of the right hemisphere parietal lobe impaired mechanisms controling the allocation of attention to the left side of extracorporal space. In addition, heminegligence was not restricted to the visual system, and has been observed in certain tactile and motor modalities as well. In this context, studies have shown that changes in manual preference and proficiency were also related to aging. At present, explanations for these age-realted trends have been incorporated into three alternative hypotheses: differential hemispheric deterioration, bilateral deterioration, and invariant asymmetry. In this study, data were obtained for 61 individuals of both sexes, right- and left-handers, in three age groups: 18 to 30 year olds, 35 to 55 year olds, and a group at age level 60 and above. Individuals were assessed on the Lateral Preference Inventory, the Tactile Line Bisection Test (TLBT), and the Visual Line Bisection Test (VLBT), and we sought to ascertain whether manual, visual, tactile and hemispatial performance would vary as a function of handedness and age. On the TLBT there were few significant differences from the zero point, trends were weak, inconsistent, and not related to handedness or age. The interdependence activation hypothesis as proposed by Bowers and Heilman was not supported, and in conclusion, this version of the TLBT was considered to be unreliable. In contrast, in response to the VLBT, pseudonegligence ocorred consistently in all of the groups. There was a significant interaction between hand and hemispace in all groups, especially when the left-hand divided lines in the left and central fields, a finding that supported the activation hypothesis. There were no significant differences between right- and left-handers, and no reliable trends across the age levels in either group. In sum, there was no evidence indicating the presence of early right hemisphere deterioration, because pseudonegligence also was also robust among the oldest groups. This finding lends more cogent support to the invariant asymmetry hypothesis.