22 research outputs found

    Pictorial relief for equiluminant images

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    Colour Relations in Form

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    The orthodox monadic determination thesis holds that we represent colour relations by virtue of representing colours. Against this orthodoxy, I argue that it is possible to represent colour relations without representing any colours. I present a model of iconic perceptual content that allows for such primitive relational colour representation, and provide four empirical arguments in its support. I close by surveying alternative views of the relationship between monadic and relational colour representation

    The Art of Seeing and Painting

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    The human urge to represent the three-dimensional world using two-dimensional pictorial representations dates back at least to Paleolithic times. Artists from ancient to modern times have struggled to understand how a few contours or color patches on a flat surface can induce mental representations of a three-dimensional scene. This article summarizes some of the recent breakthroughs in scientifically understanding how the brain sees that shed light on these struggles. These breakthroughs illustrate how various artists have intuitively understand paradoxical properties about how the brain sees, and have used that understanding to create great art. These paradoxical properties arise from how the brain forms the units of conscious visual perception; namely, representations of three-dimensional boundaries and surfaces. Boundaries and surfaces are computed in parallel cortical processing streams that obey computationally complementary properties. These streams interact at multiple levels to overcome their complementary weaknesses and to transform their complementary properties into consistent percepts. The article describes how properties of complementary consistency have guided the creation of many great works of art.National Science Foundation (SBE-0354378); Office of Naval Research (N00014-01-1-0624

    Two operational modes in the perception of shape from shading revealed by the effects of edge information in slant settings.

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    The perception of shape from shading (SFS) has been an active research topic for more than two decades, yet its quantitative description remains poorly specified. One obstacle is the variability typically found between observers during SFS tasks. In this study, we take a different view of these inconsistencies, attributing them to uncertainties associated with human SFS. By identifying these uncertainties, we are able to probe the underlying computation behind SFS in humans. We introduce new experimental results that have interesting implications for SFS. Our data favor the idea that human SFS operates in at least two distinct modes. In one mode, perceived slant is linear to luminance or close to linear with some perturbation. Whether or not the linear relationship is achieved is influenced by the relative contrasts of edges bounding the luminance variation. This mode of operation is consistent with collimated lighting from an oblique angle. In the other mode, recovered surface height is indicative of a surface under lighting that is either diffuse or collimated and frontal. Shape estimates under this mode are partially accounted for by the "dark-is-deep" rule (height ∝ luminance). Switching between these two modes appears to be driven by the sign of the edges at the boundaries of the stimulus. Linear shading was active when the boundary edges had the same contrast polarity. Dark-is-deep was active when the boundary edges had opposite contrast polarity. When both same-sign and opposite-sign edges were present, observers preferred linear shading but could adopt a combination of the two computational modes

    Quasi-Modal Encounters Of The Third Kind: The Filling-In Of Visual Detail

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    Although Pessoa et al. imply that many aspects of the filling-in debate may be displaced by a regard for active vision, they remain loyal to naive neural reductionist explanations of certain pieces of psychophysical evidence. Alternative interpretations are provided for two specific examples and a new category of filling-in (of visual detail) is proposed

    Experimental phenomenology on the role of chromatic accentuation in reading tasks

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    According to Gestalt psychologists, color is considered a secondary attribute and a less effective tool if compared to shape, luminance and motion. In this work novel and meaningful visual properties given by chromatic variations in the reading process in normal and dyslexic readers have been studied. It was shown that color highlights wholeness, parts-whole organization and phenomenal fragmentation during reading and comprehension tasks in reading texts made of words and non-words modified through several color conditions: monochromatic (the whole text colored with only one color); word (each word colored in different color); half word (half word colored in a color different from the one of the second half); syllable (every syllable in a different color); letter (each letter in a different color). The aleatory variables here considered were: the reading time, the reading errors and the incorrect answers given in a comprehension test. The outcomes demonstrated that these variables are all directly related and strongly affected by the five chromatic conditions. These findings illustrate similar trends in the four groups of readers: children and adults, normal and dyslexic readers. Further possible researches and eventually some clinical applications are also discussed along with some questions related to color vision. They suggest the main purposes of color for living beings which is that to generate wholeness, parts-whole organization and perceptual fragmentation

    Varieties of Attractiveness and their Brain Responses

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    A tablet computer-assisted motor and language skills training programme to promote communication development in children with autism: development and pilot study

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    Autism is a heterogenous condition, encompassing many different subtypes and presentations. Of those people with autism who lack communicative speech, some are more skilled at receptive language than their expressive difficulty might suggest. This disparity between what can be spoken and what can be understood correlates with motor and especially oral motor abilities, and thus may be a consequence of limits to oral motor skill. Point OutWords, tablet-based software targeted for this subgroup, builds on autistic perceptual and cognitive strengths to develop manual motor and oral motor skills prerequisite to communication by pointing or speaking. Although typical implementations of user-centred design rely on communicative speech, Point OutWords users were involved as co-creators both directly via their own nonverbal behavioural choices and indirectly via their communication therapists’ reports; resulting features include vectorised, high-contrast graphics, exogenous cues to help capture and maintain attention, customisable reinforcement prompts, and accommodation of open-loop visuomotor control
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