RESUMO

One major issue concerning investigations of visual perception is determination of the geometrical properties of visual space. To address this issue, one must determine the relationships between geometrical features of visual space, distance, direction, angle, and size. Consistent evidence indicates that visual angle is a determinant of perceived exocentric distance. Previous evidence suggests that exocentric distance and direction are hierarchically processed, with distance preceding direction. The present study investigated the relationship between the perceptual processing of egocentric direction and exocentric direction using a task that independently provides both perceptual variables in a single judgment. The results indicated that egocentric directions were systematically overestimated, and this was not caused by either the global shape of the layout or leg length effects. Exocentric directions presented a discontinuous pattern of overestimation of smaller angles that were subtended by radial orientations and accuracy of right angles that were subtended by horizontal orientations. This could be explained by the anisotropy of visual space, a well-established phenomenon from visual space studies. The analysis of the association between the processing of these two variables revealed independence between them in which exocentric direction processing did not depend on the processing of egocentric direction processing, and vice versa. The present results and prior evidence converge on the notion of hierarchical processing in which the visual system processes the egocentric distance of objects followed by exocentric distance processing and subsequent processing. The precise positions of egocentric and exocentric directions in this chain of processing remain to be determined.(AU)

Assuntos

RESUMO

One major issue concerning investigations of visual perception is determination of the geometrical properties of visual space. To address this issue, one must determine the relationships between geometrical features of visual space, distance, direction, angle, and size. Consistent evidence indicates that visual angle is a determinant of perceived exocentric distance. Previous evidence suggests that exocentric distance and direction are hierarchically processed, with distance preceding direction. The present study investigated the relationship between the perceptual processing of egocentric direction and exocentric direction using a task that independently provides both perceptual variables in a single judgment. The results indicated that egocentric directions were systematically overestimated, and this was not caused by either the global shape of the layout or leg length effects. Exocentric directions presented a discontinuous pattern of overestimation of smaller angles that were subtended by radial orientations and accuracy of right angles that were subtended by horizontal orientations. This could be explained by the anisotropy of visual space, a well-established phenomenon from visual space studies. The analysis of the association between the processing of these two variables revealed independence between them in which exocentric direction processing did not depend on the processing of egocentric direction processing, and vice versa. The present results and prior evidence converge on the notion of hierarchical processing in which the visual system processes the egocentric distance of objects followed by exocentric distance processing and subsequent processing. The precise positions of egocentric and exocentric directions in this chain of processing remain to be determined.

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RESUMO

Qual a relação entre competência cognitiva individual e/ou de uma população, em âmbito nacional, com diferentes indicadores da qualidade de vida individual ou coletiva? Revisando diferentes estudos que pontuam, contemporaneamente, o papel relevante que inteligência individual ou coletiva tem desempenhado, nossa análise demonstra que os QI(s), individual e/ou nacional estão significativamente associados a uma grande variedade de atributos sociais, econômicos, educacionais, políticos, geográficos, epidemiológicos, tecnológicos e de saúde. Em outras palavras, QI é positivamente correlacionado com um vasto, e variável, conjunto de relevantes indicadores para nossa qualidade de vida.(AU)

What is the relation between the individual or national cognitive competence with different indicators of quality of life for an individual or for a nation? We reviewed several studies which provide that individual, our national, intelligence, has had, actually, um very important role in the modern society. Our analysis indicated that the IQ(s), individual or national, are associated with a large range of social, economic, educational, political, demographic, epidemiological, technological, and health indicators, both for individuals and for nations. In other words, IQ(s) are positively correlated with a wide range and important indicators of our quality of life.(AU)

RESUMO

The main purpose of the present study was to investigate whether in natural environment, using very large physical distances, there is a trend to overconstancy for distance estimates during development. One hundred and twenty-nine children aged 5 to 13 years old and twenty-one adults (in a control group), participated as observers. The observer's task was to bisect egocentric distances, ranging from 1.0 to 296.0 m, presented in a large open field. The analyses focused on two parameters, constant errors and variable errors, such as measuring accuracy and precision, respectively. A third analysis focused on the developmental pattern of shifts in constancy as a function of age and range of distances. Constant error analysis showed that there are two relevant parameters for accuracy, age, and range of distances. For short distances, there are three developmental stages: 5-7 years, when children have unstable responses, 7-11, underconstancy, and 13 to adulthood, when accuracy is reached. For large distances, there is a two-stage development: 5-11 years, with severe underconstancy, and beyond this age, with mild underconstancy. Variable errors analyses indicate that precision is noted for 7 year-old children, independently of the range of distances. The constancy analyses indicated that there is a shift from constancy (or slightly overconstancy) to underconstancy as a function of physical distance for all age groups. The age difference is noted in the magnitude of underconstancy that occurs in larger distances, where adults presented lower levels of underconstancy than children. The present data were interpreted as due to a developmental change in cognitive processing rather than to changes in visual space perception.

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RESUMO

Binocular cues were considered the prevailing on specifying depth since the beginning of vision research. In the present study, two perceptual responses, the classical verbal report and a more recent method, open-loop walking, were used to assess the role of binocular information for egocentric distance perception. In two cue conditions environments, full- and reduced-cue, observers judge and walked egocentric distances of stimuli presented at eye-level, under binocular or monocular viewing. Results indicated perceptual constancy for open-loop walking and binocular responses, as well as poor performances under strong degradation on visual information (reduced-cue under strong monocular viewing), thus presenting evidence to support the fundamental role of binocular information on perception of egocentric distances. Besides that, visually directed actions could be adequate measures of perceived distance, with a better reliability than verbal report, since they were quite free of intrusion of inferential processes and perceptual tendencies. In addition, reduced head movements, side-to-side as well as back and forth deflexion movements, could have contributed to a near perfect coupling between binocular disparity information and open-loop walking responses.

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RESUMO

Sistemas de referência (frames of reference) são definidos como um locus ou conjunto de loci em relação ao qual as localizações espaciais são determinadas. Os sistemas de referência egocêntricos definem as localizações espaciais em relação ao observador, enquanto que nos sistemas de referência alocêntricos, as localizações são determinadas em relação a loci externos ao observador. Analisamsediversas evidências da utilização destes sistemas de referência pelo sistema visual humano, tanto para tarefas de percepção visual quanto para tarefas de navegação. Hipóteses da dissociação dosistema visual em função destes sistemas de referência são evidenciadas por resultados de estudos neuropsicológicos. O conjunto das evidências experimentais indica uma efetiva interação entre codificações em sistemas de referência egocêntricos e alocêntricos, de modo que os sistemas visual e visomotor introduzem transformações nas coordenadas de um sistema em função de outro, adequando a informação às características das diferentes tarefas. (AU)

Frame of reference is a locus or a set of loci in relation to which spatial locations are determined. Egocentrical frames of reference define spatial locations in relation to observer; in allocentricalframes of reference, spatial locations are determined in relation to external loci. Several evidences of usefulness of frames of references to human visual system are analysed, to perceptual tasks as well as navigational tasks. Neuropsychological studies provided empirical support to hypothesis ondissociation of visual system as a function of frames of reference. The whole of experimental evidenceindicates an effective interaction between codings in egocentrical and allocentrical frames of reference,thus visual and visuomotor systems introduce transformations on coordinates of a frame on another,adjusting information to different tasks requirements. (AU)

Assuntos

RESUMO

Sistemas de referência (frames of reference) são definidos como um locus ou conjunto de loci em relação ao qual as localizações espaciais são determinadas. Os sistemas de referência egocêntricos definem as localizações espaciais em relação ao observador, enquanto que nos sistemas de referência alocêntricos, as localizações são determinadas em relação a loci externos ao observador. Analisamsediversas evidências da utilização destes sistemas de referência pelo sistema visual humano, tanto para tarefas de percepção visual quanto para tarefas de navegação. Hipóteses da dissociação dosistema visual em função destes sistemas de referência são evidenciadas por resultados de estudos neuropsicológicos. O conjunto das evidências experimentais indica uma efetiva interação entre codificações em sistemas de referência egocêntricos e alocêntricos, de modo que os sistemas visual e visomotor introduzem transformações nas coordenadas de um sistema em função de outro, adequando a informação às características das diferentes tarefas.

Frame of reference is a locus or a set of loci in relation to which spatial locations are determined. Egocentrical frames of reference define spatial locations in relation to observer; in allocentricalframes of reference, spatial locations are determined in relation to external loci. Several evidences of usefulness of frames of references to human visual system are analysed, to perceptual tasks as well as navigational tasks. Neuropsychological studies provided empirical support to hypothesis ondissociation of visual system as a function of frames of reference. The whole of experimental evidenceindicates an effective interaction between codings in egocentrical and allocentrical frames of reference,thus visual and visuomotor systems introduce transformations on coordinates of a frame on another,adjusting information to different tasks requirements.

Assuntos

RESUMO

As indicações de distância dependem substancialmente de como o observador é solicitado a responder. Quando um observador tenta ajustar a magnitude de uma extensão posicionada no chão em profundidade para emparelhá-la a uma outra extensão posicionada num plano frontoparalelo, os resultados sugerem uma forte compressão na profundidade percebida, mesmo em distâncias consideradas pequenas, Loomis, Da Silva, Fujita e Fukusima (1992), todavia, encontraram que quando estas mesmas extensões são indicadas pela resposta de caminhar visualmente dirigida, sem continuamente ver o alvo, tal compressão praticamente desaparece. Nesta conferência nós discutimos quatro hipóteses que podem explicar estes resultados aparentemente paradoxais (AU)

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RESUMO

Estimativas verbais da dimensao espacial distancia (egocentrica e exocentrica) exibiram um espaco visual caracterizado pela funcao perfeitamente linear, indicando o fenomeno da constancia perceptiva. Esse achado permite inferir um possivel espaco visual euclidiano apontando para a ocorrencia do espaco fisico na representacao visual da cena. A constancia perceptiva perfeita foi explicada pela magnitude de fontes de informacoes visuais especificas a dimensao espacial e disponiveis ao observador. Nossos achados poderao dar suporte as teorias do espaco visual construido a partir das transformacoes vetoriais produzidas pela quantidade e qualidade da fonte de informacao visual.

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RESUMO

Pessoas controlam através da informaçäo visual disponível suas açöes para realizar tarefas com metas específicas. Em uma tarefa do caminhar direto para pontos de evitaçäo visualizados previamente com objetivos de evitar colisäo contra um obstáculo fixo, foram analisados os erros de desvio ou o componentes de locomoçäo, a translaçäo e a rotaçäo. Os erros angulares de desvios foram observados dentro dos limites considerados para uma acurácia da orientaçäo espacial percebida, e produziram componentes da locomoçäo acurados para evitar colisäo. A acurácia foi explicada por dois fatores, a disponibilidade de fontes de informaçöes espaciais e a potência das propriedades da cena, que permitiram aos observadores a construçäo de uma representaçäo visual da cena física, e a manutençäo da orientaçäo espacial durante a locomoçäo para alvos predeterminados de modo seguro a fim de evitar possíveis acidentes de choque contra obstáculos

Assuntos