Independence of egocentric and exocentric direction processing in visual space

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.

Independence of egocentric and exocentric direction processing in visual space

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)

Inteligência humana e suas implicações / Human intelligence and its implications

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)

One-dimensional and multi-dimensional studies of the exocentric distance estimates in frontoparallel plane, virtual space, and outdoor open field.

The aim of this study is twofold: on the one hand, to determine how visual space, as assessed by exocentric distance estimates, is related to physical space. On the other hand, to determine the structure of visual space as assessed by exocentric distance estimates. Visual space was measured in three environments: (a) points located in a 2-D frontoparallel plane, covering a range of distances of 20 cm; (b) stakes placed in a 3-D virtual space (range = 330 mm); and (c) stakes in a 3-D outdoors open field (range = 45 m). Observers made matching judgments of distances between all possible pairs of stimuli, obtained from 16 stimuli (in a regular squared 4 x 4 matrix). Two parameters from Stevens' power law informed us about the distortion of visual space: its exponent and its coefficient of determination (R2). The results showed a ranking of the magnitude of the distortions found in each experimental environment, and also provided information about the efficacy of available visual cues of spatial layout. Furthermore, our data are in agreement with previous findings showing systematic perceptual errors, such as the further the stimuli, the larger the distortion of the area subtended by perceived distances between stimuli. Additionally, we measured the magnitude of distortion of visual space relative to physical space by a parameter of multidimensional scaling analyses, the RMSE. From these results, the magnitude of such distortions can be ranked, and the utility or efficacy of the available visual cues informing about the space layout can also be inferred.

Distance perception in a natural outdoor setting: is there a developmental trend to overconstancy?

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.

One-dimensional and multi-dimensional studies of the exocentric distance estimates in frontoparallel plane, virtual space, and outdoor open field

The aim of this study is twofold: on the one hand, to determine how visual space, as assessed by exocentric distance estimates, is related to physical space. On the other hand, to determine the structure of visual space as assessed by exocentric distance estimates. Visual space was measured in three environments: (a) points located in a 2-D frontoparallel plane, covering a range of distances of 20 cm; (b) stakes placed in a 3-D virtual space (range ≈ 330 mm); and (c) stakes in a 3-D outdoors open field (range = 45 m). Observers made matching judgments of distances between all possible pairs of stimuli, obtained from 16 stimuli (in a regular squared 4 × 4 matrix). Two parameters from Stevens' power law informed us about the distortion of visual space: its exponent and its coefficient of determination (R2). The results showed a ranking of the magnitude of the distortions found in each experimental environment, and also provided information about the efficacy of available visual cues of spatial layout. Furthermore, our data are in agreement with previous findings showing systematic perceptual errors, such as the further the stimuli, the larger the distortion of the area subtended by perceived distances between stimuli. Additionally, we measured the magnitude of distortion of visual space relative to physical space by a parameter of multidimensional scaling analyses, the RMSE. From these results, the magnitude of such distortions can be ranked, and the utility or efficacy of the available visual cues informing about the space layout can also be inferred (AU)

En este estudio se pretendía cubrir un doble objetivo. Por un lado, determinar cómo el espacio visual, evaluado en términos de estimaciones de distancias exocéntricas, se corresponde con el espacio físico. Y, por otro lado, determinar la estructura del espacio visual a partir de las mismas estimaciones de distancias. Para ello, registramos la respuesta (métrica) de los observadores en tres entornos espaciales: (a) puntos localizados en un plano 2-D (frontoparalelo) en un rango de distancias de 20 cm; (b) estacas vistas esteroscopicamente y situadas en un espacio virtual 3-D (rango de 33 cm); y (c) estacas físicas dispuestas en un espacio abierto exterior (rango de 45 m). Los observadores hicieron juicios de emparejamiento de distancias entre todos los posibles pares que se podían formar con 16 estacas (dispuestas en una matriz cuadrada regular de 4 filas × 4 columnas). Utilizamos dos parámetros de la ley potencial de Stevens, que nos informaron de la distorsión percibida del espacio visual: el exponente y el coeficiente de determinación (R2). Los resultados permitieron ordenar la magnitud de la distorsión encontrada en cada entorno experimental, proporcionando información sobre la utilidad y eficacia de las claves de profundidad disponibles. Nuestros datos concuerdan con los obtenidos en estudios previos en mostrar una cierta anisotropía espacial que difiere en cada entorno. Adicionalmente, aplicamos el escalamiento multidimensional y medimos la distorsión a través del RECM, lo que también nos permitió ordenar la magnitud de las distorsiones en cada contexto, así como la eficacia de las claves visuales de distancia (AU)

Distance perception in a natural outdoor setting: is there a developmental trend to overconstancy?

The main purpose of the present study was to investigate whether in natural environment, using very large physical distances, there isa trend to over constancy 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, under constancy, and 13 to adulthood, when accuracy is reached. For large distances, there is a two-stage development: 5-11 years, with severe under constancy, and beyond this age, with mild under constancy. 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 over constancy) to under constancy as a function of physical distance for all age groups. The age difference is noted in the magnitude of under constancy that occurs in larger distances, where adults presented lower levels of under constancy than children. The present data were interpreted as due to a developmental change in cognitive processing rather than to changes in visual space perception (AU)

El principal objetivo de este estudio fue investigar si en un medio natural, empleando distancias físicas muy grandes, hay una tendencia a sobre-constancia para las estimaciones de distancias durante el desarrollo evolutivo. Participaron como observadores 129 niños de edades entre 5 y 13 años y 21 adultos (en un grupo control). La tarea de los observadores consistió en biseccionar unas distancias egocéntricas, que variaban entre 1,0 y 296,0 m, presentadas en un gran campo abierto. El análisis se centró en dos parámetros, error constante y error variable, de la exactitud y precisión de medida, respectivamente. Un tercer análisis se centró en el patrón evolutivo de cambios en la constancia en función de la edad y el rango de distancias. El análisis de los errores constantes mostró que hay dos parámetros relevantes para la precisión, edad y rango de distancias. Para distancias cortas, hay tres fases evolutivas: 5-7 años, cuando los niños dan respuestas inestables, 7-11, infra-constancia, y 13 años hasta la adultez, cuando alcanzan la exactitud (constancia). Para las distancias largas, hay un desarrollo de dos fases: 5-11 años, con infra-constancia severa, y más allá de esta edad, con ligera infraconstancia. El análisis del error variable indica que se alcanza precisión a partir de 7 años, con independencia del rango de distancias. En análisis de la constancia indica que existe un cambio desde la constancia (o una ligera sobre-constancia) a infra-constancia en función de la distancia física para todos los grupos de edad. La diferencia de edad se nota en la magnitud de la infra-constancia que ocurre en las distancias más largas, donde los adultos presentaban niveles menores de infra-constancia que los niños. Estos datos se interpretan como debidos a un cambio evolutivo en el procesamiento cognitivo más que a cambios en la percepción visual del espacio (AU)

Visual angle as determinant factor for relative distance perception

Visual angles are defined as the angle between line of sight up to the meanpoint of a relative distance and the relative distance itself. In one experiment,we examined the functional aspect of visual angle in relative distanceperception using two different layouts composed by 14 stakes, one of themwith its center 23 m away from the observation point, and the other 36 maway from the observation point. Verbal reports of relative distance weregrouped in 10 categories of visual angles. Results indicated visual angle as adeterminant factor for perceived relative distance as observed in the absenceof perceptual errors to distances with visual angle equal or larger than 70degrees that could be attributed to a combination of sources of visualinformation. Another finding showed a possible intrusion of non-perceptualfactors (observer’s tendencies), leading to compressed estimates to relativedistances with visual angles smaller than 70 degrees

Visual perception of extent and the geometry of visual space.

The question of how perceived extents are related to the corresponding physical extents is a very old question that has not been satisfactorily answered. The common model is that perceived extent is proportional to the product of image size and perceived distance. We describe an experiment that shows that perceived extents are substantially larger than this model predicts. We propose a model that accounts for our results and a large set of other results. The principal assumption of the model is that, in the computation of perceived extent, the visual angle signal undergoes a magnifying transform. Extent is often perceived more accurately than the common model predicts, so the computation is adaptive. The model implies that, although the perception of location and the perception of extent are related, they not related by Euclidean geometry, nor by any metric geometry. Nevertheless, it is possible to describe the perception of location and extent using a simple model.

Perceptual constancy in judgments of egocentric distance: prevailing binocular information

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.

Interações entre sistemas de referência alocêntricos e egocêntricos: evidências dos estudos com direção percebida / Interactions between allocentric and egocentric frames of reference: evidences from studies on perceived direction

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)

Interações entre sistemas de referência alocêntricos e egocêntricos: evidências dos estudos com direção percebida / Interactions between allocentric and egocentric frames of reference: evidences from studies on perceived direction

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.

Interação entre percepção visual e ação visualmente dirigida / Interaction between visual, space perception and visually guided action

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)

Ha um espaco real dentro do espaco visual

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.

Análise dos desvios angulares da locomoçäo em uma tarefa para evitar colisäo contra objeto fixo em ambiente rígido: uma breve comunicaçäo / Angular deviation analysis of locomotion in a task to avoid colision against obstacles: a brief communication

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

Analise dos desvios angulares da locomocao em uma tarefa para evitar colisao contra objeto fixo em ambiente rigido: uma breve comunicacao

Pessoas controlam atraves da informacao visual disponivel suas acoes para realizar tarefas com metas especificas. Em uma tarefa do caminhar direto para pontos de evitacao visualizadas previamente como objetivos d evitar colisao contra um obstaculo fixo, foram analisados os erros de desvio ou os componentes da locomocao, a translacao e a rotacao. Os erros angulares de desvio foram observados dentro dos limites considerados para uma acuracia da orientacao espacial percebida, e produziram componentes da locomocao acurados para evitar colisao. A acuracia foi explicada por dois fatores, a disponibilidade de fontes de informacoes espaciais e a potencia das propriedades da cena, que permitiram aos observadores a construcao de uma representacao visual da cena fisica, e a manutencao da orientacao espacial durante a locomocao para alvos predeterminados de modo seguro a fim de evitar possiveis acidentes de choque contra obstaculos.