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.

The present study investigated the influence of emotional valence on the spatial stimulus-key location correspondence effect in three experiments using the Affective Spatial Correspondence task (AffSCt). We initially reanalyzed the results of Conde et al. (2011) according to the model proposed by Proctor (2013). In that study, compatible and incompatible responses were chosen according to the participants' team preference. In one block, the volunteers had to press a key on the same side for the Favorite team and on the opposite side for the Rival team. In another block, a reverse code was used. We found that responses were faster for the Favorite-compatible/Rival-incompatible condition (614 ms) compared with the Favorite-incompatible/Rival-compatible condition (691 ms). The same experimental arrangement was replicated in another Brazilian city, and similar results were found. Additionally, we employed non-affective "fake" soccer teams as a control condition, and no mapping-rule effect was observed. Finally, a final experiment that used the same design but different non-affective stimuli (yellow and blue bars) was performed to provide further evidence that the valence effect in the present experimental paradigm only occurs with affective stimuli. As expected, non-affective stimuli did not produce an overall advantage for any mapping rules, corroborating earlier findings with similar mixed designs. The results confirmed the previous findings and validity of the AffSCt as a methodology to investigate the effects of emotional valence on stimulus-response correspondence. However, we are unable to provide a conclusive explanation to support the several hypotheses proposed previously in our paper and by Proctor (2013).

A visual stimulus (e.g., a letter, word, or object) may have a lasting effect on the processing of subsequent stimuli. The present study verified the priming effect of a figure (i.e., five-petal daisy) on manual reaction time (MRT) to another equal or different five-petal daisy. Two distinct groups were tested. One group was instructed that the five-petal daisy represented a human hand. The other group was instructed that the five-petal daisy represented a flower. The figures in the pairs of stimuli could share or not share some features such as handedness and view. In both groups, after being informed whether the five-petal daisy represented a flower or human hand, an uninformative flower was presented for 200 ms in the center of the screen. After 1000 ms, a second flower was presented in the same location until the observer responded by pressing a left or right switch. The results showed that prior presentation of the five-petal daisy affected MRT only when the figure represented a human hand. Furthermore, an opposite effect of view on MRT was found. The shorter MRT to the back (dorsal) view of the figure that represented a human hand could be attributable to a faster response to the dorsal view of a hand figure made with a prone posture of the participants' hand than to a front (palm) view. The longer MRT to the back view of the figure that represented a flower may be due to a mental rotation of the object along its vertical axis before selecting the correct response because the response was based on the position of the asymmetrical petal in the canonical front view of the daisy.

Diversos estudos empregando ações visualmente dirigidas como indicadores da distância percebida demonstraram que as pessoas podem caminhar acuradamente para alvos distantes em até 22m. Estes resultados, somados aos relacionados com medidas perceptuais de distância percebida, demonstram que estas respostas são controladas por uma única variável interna, denominada de localização visualmente percebida. No presente estudo, comparamos os desempenhos em tarefas de bissecção, realizadas por caminhada visualmente dirigida, ou por emparelhamento perceptual. Os observadores (N=20) caminharam ou ajustaram a posição de uma ponteira ao ponto médio da distância egocêntrica de um alvo (5, 10 or 15m), sob observação binocular. Os resultados indicaram acurácia em ambas respostas, sem diferenças significativas entre elas, o que sustenta a hipótese de uma única variável interna controlando ação e percepção. Este invariante pode ser determinado por um conjunto ponderado de fontes de informação.

Several studies using visually directed actions as indicators of perceived distance showed that people could accurately walk toward targets far up to 22m. Those results, summed up to those related to perceptual measures of perceived distance, showed that those responses were controlled by a single internal variable, namely visually perceived location. In the present study, we compared performance in bisection tasks, performed by open-loop walking or by perceptual matching. Observers (N=20) walked toward or adjust a pointer to the mean point of an egocentric distance (5, 10 or 15m), under binocular viewing. Results indicated accuracy on both responses, with no reliable differences between them, supporting the hypothesis of a single internal variable controlling action and perception. This invariant may be determined by a weighted set of sources of information.

Os indícios binoculares foram considerados a informação prevalente na determinação da profundidade desde os primórdios da pesquisa em visão. No presente estudo, duas respostas perceptivas, o clássico relato verbal e um método mais recente, o caminhar em ciclo aberto, foram empregados para verificar o papel da informação binocular na percepção de distâncias egocêntricas. Em duas condições de indícios, plena e reduzida de indícios visuais, os observadores julgaram e caminharam distâncias egocêntricas de estímulos apresentados no nível do olho, sob visão binocular ou monocular. Os resultados indicaram constância perceptual para caminhar em ciclo aberto e respostas sob visão binocular, assim como baixa performance sob forte degradação da informação visual (condição reduzida de indícios sob visão monocular), nos fornecendo subsídios para sustentar o papel fundamental da informação binocular na percepção de distâncias egocêntricas. Além disso, as ações visualmente dirigidas podem ser medidas adequadas da distância percebida, com fidedignidade maior que o relato verbal, já que é relativamente incólume à intrusão de processos inferenciais e tendências perceptuais. Somando-se a isso, reduzidos movimentos da cabeça, tanto translacionais quanto deflexões para frente e para trás, podem ter contribuído para uma quase perfeita interação entre a disparidade binocular e as respostas de caminhar em ciclo aberto.

Binocular cues were considered the prevailing information 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 judged 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 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.

O presente estudo focaliza as questões sobre a ontologia da cor, essencialmente a discussão entre Fisicalismo e Subjetivismo. Analisando estes debates, entre uma concepção físicalista, que considera a cor uma propriedade física dos objetos externos, e uma concepção subjetivista, em que a cor é identificada com um processamento mental, encontrou-se argumentação diversa, desde questões silogísticas até evidências experimentais. Entretanto, uma hipótese alternativa é oferecida, o Psicofisicalismo, em que evidências da psicofísica da cor e modelos evolucionários fornecem uma descrição da essência da cor. A cor deve ser considerada uma propriedade dual, com uma vertente física e uma psicológica estreitamente relacionadas.

The present study focuses on ontological issues about color, essentially the debate between Physicalism and Subjectivism. Analyzing those discussions, between a physical conception, considering color as a physical property of external objects, and a subjectivist one, which identify color with mental processing, we found syllogistical problems, experimental evidences, and other kinds of arguments supporting the conceptions. Nevertheless, an alternative hypothesis is offered, Psychophysicalism, in which psychophysical experimental support and evolutionary models provide a description of color ontology. Color must be considered a dual property, owning a physical and a psychological feature that are tightly related.

As pessoas, durante uma tarefa de caminhar sem visão para alvos previamente visualizados, usualmente realizam-na acuradamente, mesmo sem feedback visual. Quando falham, acidentes, como quedas, podem ocorrer. Estas falhas são geralmente associadas com erros humanos durante os processos de tomada de decisão, de ação ou de percepção. O presente trabalho foi desenvolvido para verificar se tais falhas, numa tarefa de evitar colisão, são associadas à orientação espacial e a tendências do observador. Planejamento: 4 grupos experimentais (Cena Completa, obstáculo e pontos de desvio; Imaginar, somente obstáculo; Sem Obstáculo; somente pontos de desvio; 10s de Atraso, obstáculo e pontos de desvio) x 3 distâncias do obstáculo (três, sete e 12 metros) x 2 distâncias de desvio (0,5 e 1,0 metro). Os observadores observaram a cena e, então, caminharam sem visão para os pontos de evitação. Os resultados mostraram uma acurácia no grupo Cena Completa, o que sugere uma pronunciada ação da informação visual na coordenação de comportamentos motores. A subestimativa encontrada nos outros indica que processos cognitivos, como a tendência do observador, podem conduzir a erros na ação. A acurácia na distância caminhada entre os pontos de desvio a 1,0m pode ser devida ao conforto da situação ou à forte ação da dimensão frontoparalela.

During a task of blinded walking to previously seen targets, people often do it accurately, even without vision feedback. When they fail, accidents may happen, like falling. These failures are often associated with human mistakes during decision-making processes, action or perception. The present study was designed in order to verify if these failures, in a collision avoidance task, are associated to the spatial orientation and to observers' tendencies. Design: 4 experimental groups (Whole Scene, obstacle and avoidance points; Imagine, only obstacle; Without obstacle; avoidance points; 10sec Delay, obstacle and avoidance points) x 3 obstacle distances (three, seven and 12 meters) x 2 avoidance distances (0.5 and 1.0 meter). The observers saw the scene and then blinded walked to the avoidance points. The results showed an accuracy in the Whole Scene group, that suggest a powerful action of the visual information in the coordination of motor behaviors. The undershoot found on the others indicates that cognitive processes, like observers' tendencies, might lead to mistakes in action. The accuracy in the walked distance between the avoidance points at 1.0m may be due to a comfortable situation or to the powerful action of fronto-parallel dimension.