Eight-letter upper case arrays containing vertically symmetrical (VS), e.g., A-T-U-W, horizontally symmetrical (HS), e.g., B-D-C-E, doubly symmetrical (DS), e.g., H-I-O-X, and non-symmetrical (NS), e.g., F-G-L-R, were tachistoscopically exposed bilaterally for 50 ms. to fifteen male and fifteen female undergraduates. The number of letters correctly recognized for each classification condition was used as the criterion measure. A fixed, two-factor design with the second factor being repeated was analyzed using a repeated measures analysis of variance. Consequent to testing Null Hypothesis 1 (that there is no difference between the classification conditions), a check was made for the presence of a significant interaction between gender and classification condition (Null Hypothesis 2). Because Null Hypothesis 1 was rejected and there was no interaction present, the classification group means were tested using a post hoc multiple comparison procedure identified as Tukey's Honestly Significant Difference (HSD) test. Test statistics for the Tukey HSD contrasts found that significantly more VS letters were reported than DS, HS, and NS letters. Significantly more DS letters were reported than HS and NS letters. No difference in report accuracy was found between HS and NS letters. This is in sharp contrast to studies that count only responses reported in the same left-to-right order as the tachistoscopic presentation, i.e., order of report. Previous studies using an order of report method found vertically asymmetrical letters to be reported more accurately than vertically symmetrical ones. The present study disregarded order of from an order of report. It was emphasized that the subject maintain focus on the fixation dot and not attempt to scan the letter-array pattern in a left-to-right direction, as the lettersdid not have to be reported in their respective positions. A different explanation for the Harcum (1964) directionality and Bryden (1968) masking interpretations follows from an order of report method activating additional processing mechanisms such as working memory that are ordinarily not needed to process letter features.Results obtained by the present study are discussed in terms of a reversal of spatial information for touch, kinesthesis, and sound to match the brain’s reversed retino-cortical projection. / Department of Educational Psychology

This study addresses areas in cerebral dominance theory which elementary classroom teachers should be aware of when developing instructional strategies to enhance the learning experiences of children. Presented are past and present findings on cerebral dominance theory, giving the reader some understanding of what has been found about the manner in which children process information. The characteristics and processes of the two halves of the cerebrum have been discussed and possible applications and misapplications of this information have been given. It is concluded that students process information in different ways and that the data can be useful when examining teaching techniques and learning styles. Some specific recommendations have been given to help teachers provide activities and instruction to develop both sides of the brain.

A large body of research has depicted relative arousal of the left and right cerebral hemispheres as related to utilization of particular defensive coping styles, level of anxiety, and perceptual styles. The right and left hemispheres are also presented in the literature as differing in visual-spatial and verbal-auditory short term memory abilities. The present research studied 127 right handed undergraduates' relative performance on forward spatial and digits memory spans in relation to hemispheric lateralization and other perceptual and personality variables hypothesized in the literature to be related to hemispheric arousal. It was hypothesized that the forward spatial and digit memory spans would display asymmetrical sensitivity to hemispheric arousal. That is, in a series of successive factor analyses, a hemispheric balance factor, a trait anxiety factor, and a short term memory factor would emerge. The three factors were hypothesized to be unrelated to each other. During an initial group pretesting, subjects were given pencil and paper measures of handedness, trait anxiety, and several defensive coping styles. During a second individual testing, subjects were administered measures of short term memory, field independence, and a computerized presentation of geometric designs which measured the subjects ability to detect differences which occurred at either the global or analytic level (Navon task). The factor analyses revealed only the hypothesized trait anxiety factor. The hypothesized short term memory and hemispheric balance of arousal factors did not emerge. Instead, a. defensive coping style factor and separate verbal—auditory and visual-spatial short term memory factors emerged. Several methodological difficulties of the present study which possibly contributed to the failure of the two hypothesized factors to emerge were discussed. Several additional findings, including sex differences in hemispheric lateralization, were presented. Also, signal detection analysis revealed a pattern such that trait anxious subjects were biased toward over-reporting differences on the Navon task. Implications for further research were presented.

M.A. (Psychology) / Research investigating the connection between Functional Hemispherical Asymmetry (FHA) and perception of affect in clinical as well as normal populations, is characterised by contradictory findings with regard to the role of the different hemispheres, especially as regards the perception of various valencies of emotions. Although a majority of studies indicates that the right hemisphere (RH) is superior in the perception of all valencies and emotions - positive as well as negative - there are numerous studies indicating a possible differential processing of positive and negative emotions by the hemispheres. Although various researchers try to lay the above contradictory findings and the general lack of consensus at the door of methodological problems/inequalities or error variances, the literature is increasingly pointing to the existence of evidently reliable individual differences between people as regards their hemispherical functioning. The problem investigated in the current study, is to determine the possible role of the organismic variables in FHA, i e variables seated in the individual who is making the observation. In this study, the focus is specifically on the role of sex and the temperament dimension of introversion-extraversion. The objectives of this study are to determine whether there are significant differences in the direction of these hemispherical differences, as well as the relative performance, of groups divided according to sex and temperament characteristics, and whether the relevant organismic variables offer a possible means of explaining the contradictions in research results on FHA and the perception of emotion. In this study, the measuring of FHA is operationalised in terms of the differential performance, measured in terms of accuracy and speed of observation (response latency) of the hemispheres in the perception of different valencies of emotional stimuli (positive versus negative, and approach versus avoidance emotions).. The subject population comprised a group of students selected in terms of sex and temperament (introversion-extraversion). Selection in terms of introversion-extraversion was done on the basis of subjects' performance in the Personality Questionnaire Form B (Schepers, 1991): persons falling in the lower and upper three stanines of the scale respectively were identified as introverts and extraverts. Only right-handed subjects with no history of brain injury were used for the study. Differential hemispherical performance in terms of response accuracy and latency was determined by means of the Divided Visual Field Technique (DVFT). Although the reliability data of this technique are generally not entirely satisfactory when measured in terms of psychometric test standards, an effort was made to enhance the reliability of the technique in this study by controlling specific stimulus and response variables (inter alia the exposure time and the use of both hands for a response) during the experimental design.

The study of lateralisation has taken several forms ranging from investigating morphological asymmetries to research on lateralised motor and perceptual functions with many studies successfully evidencing lateralisation in a variety of species. This study, featuring three species (olive baboons, rhesus macaques, and spotted hyaenas) investigated visual field biases with the aim of determining whether emotional valence underpins these biases whilst also considering the influence of a number of other factors such as emotional intensity, age, sex, rank, and, for the first time, oestrus cycles (olive baboons only). This study aimed to establish whether Campbell’s (1982) Right Hemisphere Hypothesis or Silberman & Weingartner’s (1986) Valence Hypothesis offered the more valid theory for the lateralisation of emotion by considering interactions across the full spectrum of emotion – a question the almost exclusive investigation of negatively affective scenarios by previous studies has been unable to answer. Furthermore, this study provided a new methodology for investigating behavioural lateralisation by suggesting that separating the visual spectrum into five fields (extreme left, mid left, centre, mid right and extreme right) allows a more accurate insight into the lateralisation of visual perception than the traditional hemifield model. Finally, a more conservative method is proposed for analysing behavioural data in future studies from this field and suggests that these methods provide a more accurate representation of the lateralisation of emotion than those previously employed. A population-level left side bias was found for the spotted hyaenas, thus providing the first evidence of significantly lateralised behaviour in a large carnivore and, for this species at least, lending some support to Campbell’s (1982) Right Hemisphere hypothesis but as population-level biases were not found for either of the other species it may be premature to suggest this support is unequivocal. Significant age effects were found in two species as adult olive baboons and spotted hyaenas were both found to express significant left side biases. Spotted hyaenas were also found to express significant left side biases for females, dominant individuals, high intensity interactions, and sexual valence interactions whilst olive baboons expressed a significant left side bias during negative valence behaviours but no significant lateral biases were found in any context for rhesus macaques. In olive baboons behaviours performed by males and those of a low intensity were found to occur more frequently in the mid and central visual fields and neutral valence behaviours were less occurrent in the extreme visual fields whilst in spotted hyaenas sexual, positive and negative valence behaviours were significantly less centralised than neutral valence behaviours. Non-oestrus adult female olive baboons were significantly more strongly lateralised than in-oestrus females, thus suggesting an influence of sex hormones upon lateralisation that may also have been apparent from the hyaena data, particularly regarding the significant lateral biases observed for females and dominant individuals. Finally, this thesis discusses a number of methodological issues that were encountered during this study and provides recommendations for future research in this field. Namely, this thesis provides an updated method for calculating laterality bias that is much more suitable for species with binocular vision and details a novel method of assessing visual field preferences by considering central and peripheral visual fields as separate entities. Furthermore, this thesis suggests that the weighted method designed and implemented for this study provides a much more accurate methodological foundation for analyses which avoids the caveats that may have affected previous research and thus provides a considerably more robust template that should be encouraged for any similar subsequent studies.

Em humanos, uma série de estudos vem sugerindo que o hemisfério esquerdo é particularmente importante no controle e execução de movimentos. De modo geral, lesões no hemisfério esquerdo promovem déficits motores mais pronunciados que lesões semelhantes no hemisfério direito. Neste trabalho utilizamos a hemisferectomia unilateral para avaliar a contribuição de cada hemisfério na função motora em camundongos. Camundongos Suíços adultos foram submetidos a hemisferectomia unilateral direita (HD) ou esquerda (HE) ou aos procedimentos de controle. Quinze dias após cirurgia, a coordenação motora de cada animal foi avaliada no teste da locomoção forçada em cilindro giratório (Rotarod). A latência para a queda do grupo controle foi significativamente maior que a do grupo HD e não diferiu da do grupo HE. Para auxiliar a interpretação dos resultados obtidos no ROTAROD, uma parte dos animais foi submetida a uma bateria adicional de testes comportamentais na seguinte seqüência: teste de campo aberto, avaliação qualitativa da assimetria sensório-motora, teste da grade elevada e teste de suspensão pela cauda. De modo interessante, no teste da grade elevada, enquanto o grupo HD apresentou o desempenho da pata traseira esquerda (contralateral à lesão) significativamente pior que o da direita, os grupos Controle e HE não apresentaram diferenças entre as duas patas traseiras. De modo análogo ao observado em humanos, nossos resultados sugerem uma ação assimétrica dos hemisférios cerebrais no controle da função motora em camundongos. / A series of studies in humans have suggested that the planning and the control of movements are asymmetrically performed by the hemispheres. In general, lesions in the left hemisphere promote motor deficits that are more pronounced than similar lesions in the right hemisphere. In the present work, we used unilateral hemispherectomy to study the relative importance of each hemisphere in the control of movement in mice. Adult Swiss mice were submitted to right unilateral hemispherectomy (RH) or left unilateral hemispherectomy (LH) and sham surgery. Fifteen days after surgery, the motor coordination of each mouse was evaluated in the forced locomotion in rotating cylinder test (Rotarod). The latency to fall was significantly lower in right-hemispherectomized group as compared to control and did not differ from the left-hemispherectomized group. To help the interpretation of results obtained in the Rotarod test, a part of the sample was subjected to a additional battery of behavioral tests in the following sequence: open field test, qualitative assessment of sensory-motor asymmetry, foot fault test and tail suspension test. Interestingly, in the foot fault test, while the RH group showed significantly worse performance with the left hind limb (contralateral to the lesion) than with the right, the control group and the LH group showed no differences between both hind limbs. Similarly to what is observed in humans, our results suggest that the two hemispheres contribute asymmetrically to control of movement in mice.

Em humanos, uma série de estudos vem sugerindo que o hemisfério esquerdo é particularmente importante no controle e execução de movimentos. De modo geral, lesões no hemisfério esquerdo promovem déficits motores mais pronunciados que lesões semelhantes no hemisfério direito. Neste trabalho utilizamos a hemisferectomia unilateral para avaliar a contribuição de cada hemisfério na função motora em camundongos. Camundongos Suíços adultos foram submetidos a hemisferectomia unilateral direita (HD) ou esquerda (HE) ou aos procedimentos de controle. Quinze dias após cirurgia, a coordenação motora de cada animal foi avaliada no teste da locomoção forçada em cilindro giratório (Rotarod). A latência para a queda do grupo controle foi significativamente maior que a do grupo HD e não diferiu da do grupo HE. Para auxiliar a interpretação dos resultados obtidos no ROTAROD, uma parte dos animais foi submetida a uma bateria adicional de testes comportamentais na seguinte seqüência: teste de campo aberto, avaliação qualitativa da assimetria sensório-motora, teste da grade elevada e teste de suspensão pela cauda. De modo interessante, no teste da grade elevada, enquanto o grupo HD apresentou o desempenho da pata traseira esquerda (contralateral à lesão) significativamente pior que o da direita, os grupos Controle e HE não apresentaram diferenças entre as duas patas traseiras. De modo análogo ao observado em humanos, nossos resultados sugerem uma ação assimétrica dos hemisférios cerebrais no controle da função motora em camundongos. / A series of studies in humans have suggested that the planning and the control of movements are asymmetrically performed by the hemispheres. In general, lesions in the left hemisphere promote motor deficits that are more pronounced than similar lesions in the right hemisphere. In the present work, we used unilateral hemispherectomy to study the relative importance of each hemisphere in the control of movement in mice. Adult Swiss mice were submitted to right unilateral hemispherectomy (RH) or left unilateral hemispherectomy (LH) and sham surgery. Fifteen days after surgery, the motor coordination of each mouse was evaluated in the forced locomotion in rotating cylinder test (Rotarod). The latency to fall was significantly lower in right-hemispherectomized group as compared to control and did not differ from the left-hemispherectomized group. To help the interpretation of results obtained in the Rotarod test, a part of the sample was subjected to a additional battery of behavioral tests in the following sequence: open field test, qualitative assessment of sensory-motor asymmetry, foot fault test and tail suspension test. Interestingly, in the foot fault test, while the RH group showed significantly worse performance with the left hind limb (contralateral to the lesion) than with the right, the control group and the LH group showed no differences between both hind limbs. Similarly to what is observed in humans, our results suggest that the two hemispheres contribute asymmetrically to control of movement in mice.