It has been suggested that humans combine depth cues in a statistically optimal fashion, taking i... more It has been suggested that humans combine depth cues in a statistically optimal fashion, taking into account the exact reliability of the available cues to maximize the reliability of the depth estimate. We have reported that human performance on slant-from-texture discrimination depends on the texture type mapped onto the slanted planes. This allows a natural way of manipulating the reliability of the texture cue by simply changing the texture type. Using a slant-discrimination task we tested the reliability-sensitive combination ...
We have previously observed systematic differences in slant discrimination performance for differ... more We have previously observed systematic differences in slant discrimination performance for different types of synthetic texture (Rosas et al., VSS-2002, abstract 300). These results allowed a rank-order of textures according to their “helpfulness”—that is, how easy the slant discrimination is when a particular texture is mapped on the surface. Textures composed of circles tended to allow the best slant discrimination performance, followed by a leopard-skin like pattern, then by a “coherent” noise, and finally a fractal noise inducing ...
The present experiment was conducted to examine the integration of the motion coherence paradigm ... more The present experiment was conducted to examine the integration of the motion coherence paradigm in a synchronization task. Random-dot kinematograms were used to generate a pattern of oscillating dots representing four different coherence levels (10%, 30%, 50% and 100%) and one target-alone condition. The participants had to synchronize their arm with the coherently moving dots according to two different synchronization modes (in-phase and anti-phase). The results revealed a substantial performance decline when the target/noise ...
Abstract We have previously observed systematic differences in slant discrimination performance f... more Abstract We have previously observed systematic differences in slant discrimination performance for different types of synthetic texture (Rosas et al., VSS-2002, abstract 300). These results allowed a rank-order of textures according to their “helpfulness”—that is, how easy the slant discrimination is when a particular texture is mapped on the surface. Textures composed of circles tended to allow the best slant discrimination performance, followed by a leopard-skin like pattern, then by a “coherent” noise, and finally a fractal noise inducing ...
Thorpe et al (Nature 381, 1996) first showed how rapidly human observers are able to classify nat... more Thorpe et al (Nature 381, 1996) first showed how rapidly human observers are able to classify natural images as to whether they contain an animal or not. Whilst the basic result has been replicated using different response paradigms (yes-no versus forced-choice), modalities ( ...
Abstract The problem of surface-slant-from-texture was studied psychophysically by measuring the ... more Abstract The problem of surface-slant-from-texture was studied psychophysically by measuring the performances of five human subjects in a slant-discrimination task with a number of different types of textures: uniform lattices, randomly displaced lattices, polka dots, Voronoi tessellations, orthogonal sinusoidal plaid patterns, fractal or 1/f noise,“coherent” noise and a “diffusion-based” texture (leopard skin-like). The results show:(1) Improving performance with larger slants for all textures.(2) A “non-symmetrical” performance around ...
We have previously observed systematic differences in slant perception by means of probe adjustme... more We have previously observed systematic differences in slant perception by means of probe adjustment for different types of synthetic texture (Rosas et al, 2002 Perception 31 Supplement, 27). These results led to a rank-order of textures according to the correlation between the depicted and perceived slants, when a particular texture was mapped on the surface. Textures composed of circles tended to allow the best slant judgments, followed by a leopard-skin-like pattern, then by a'coherent'noise, and finally a fractal noise inducing ...
Recherches actuelles en sciences du sport, Oct 28, 2005
Methods Fifteen volunteers participated in each experiment and were seated comfortably on a chair... more Methods Fifteen volunteers participated in each experiment and were seated comfortably on a chair behind a table in a darkened room. The right forearm had to be put on a lever that could freely rotate in the horizontal plane and a shaft encoder recorded its position. The dynamic display was a random-dot kinematogram, created in MATLAB, using the Psychophysics Toolbox extensions (Brainard, 1997; Pelli, 1997), and materialized as a black rectangle (117cm x 119cm) continuously filled with the total number of 700 dots. It ...
The contribution of texture to the perception of slant and curvature was studied in two experimen... more The contribution of texture to the perception of slant and curvature was studied in two experiments in which we collected judgments of human subjects by means of probe adjustment. For the slant-perception experiment, our stimuli consisted of flat surfaces receding away from the subject, while for the curvature experiment we used surfaces depicting half-elliptic cylinders whose major semi-axes pointed towards the subject. Both types of stimuli were generated under perspective projection with purpose written software ...
Abstract We investigated the influence of the perceived 3D-orientation of planar elliptical shape... more Abstract We investigated the influence of the perceived 3D-orientation of planar elliptical shapes on the perception of the shapes themselves. Ellipses were projected onto the surface of a sphere and subjects were asked to indicate if the projected shapes looked as if they were a circle on the surface of the sphere. The image of the sphere was obtained from a real,(near) perfect sphere using a highly accurate digital camera (real sphere diameter 40 cm; camera-to-sphere distance 320 cm; for details see Willems et al., Perception 29, S96, ...
It has been suggested that humans combine depth cues in a statistically optimal fashion, taking i... more It has been suggested that humans combine depth cues in a statistically optimal fashion, taking into account the exact reliability of the available cues to maximize the reliability of the depth estimate. We have reported that human performance on slant-from-texture discrimination depends on the texture type mapped onto the slanted planes. This allows a natural way of manipulating the reliability of the texture cue by simply changing the texture type. Using a slant-discrimination task we tested the reliability-sensitive combination ...
We have previously observed systematic differences in slant discrimination performance for differ... more We have previously observed systematic differences in slant discrimination performance for different types of synthetic texture (Rosas et al., VSS-2002, abstract 300). These results allowed a rank-order of textures according to their “helpfulness”—that is, how easy the slant discrimination is when a particular texture is mapped on the surface. Textures composed of circles tended to allow the best slant discrimination performance, followed by a leopard-skin like pattern, then by a “coherent” noise, and finally a fractal noise inducing ...
The present experiment was conducted to examine the integration of the motion coherence paradigm ... more The present experiment was conducted to examine the integration of the motion coherence paradigm in a synchronization task. Random-dot kinematograms were used to generate a pattern of oscillating dots representing four different coherence levels (10%, 30%, 50% and 100%) and one target-alone condition. The participants had to synchronize their arm with the coherently moving dots according to two different synchronization modes (in-phase and anti-phase). The results revealed a substantial performance decline when the target/noise ...
Abstract We have previously observed systematic differences in slant discrimination performance f... more Abstract We have previously observed systematic differences in slant discrimination performance for different types of synthetic texture (Rosas et al., VSS-2002, abstract 300). These results allowed a rank-order of textures according to their “helpfulness”—that is, how easy the slant discrimination is when a particular texture is mapped on the surface. Textures composed of circles tended to allow the best slant discrimination performance, followed by a leopard-skin like pattern, then by a “coherent” noise, and finally a fractal noise inducing ...
Thorpe et al (Nature 381, 1996) first showed how rapidly human observers are able to classify nat... more Thorpe et al (Nature 381, 1996) first showed how rapidly human observers are able to classify natural images as to whether they contain an animal or not. Whilst the basic result has been replicated using different response paradigms (yes-no versus forced-choice), modalities ( ...
Abstract The problem of surface-slant-from-texture was studied psychophysically by measuring the ... more Abstract The problem of surface-slant-from-texture was studied psychophysically by measuring the performances of five human subjects in a slant-discrimination task with a number of different types of textures: uniform lattices, randomly displaced lattices, polka dots, Voronoi tessellations, orthogonal sinusoidal plaid patterns, fractal or 1/f noise,“coherent” noise and a “diffusion-based” texture (leopard skin-like). The results show:(1) Improving performance with larger slants for all textures.(2) A “non-symmetrical” performance around ...
We have previously observed systematic differences in slant perception by means of probe adjustme... more We have previously observed systematic differences in slant perception by means of probe adjustment for different types of synthetic texture (Rosas et al, 2002 Perception 31 Supplement, 27). These results led to a rank-order of textures according to the correlation between the depicted and perceived slants, when a particular texture was mapped on the surface. Textures composed of circles tended to allow the best slant judgments, followed by a leopard-skin-like pattern, then by a'coherent'noise, and finally a fractal noise inducing ...
Recherches actuelles en sciences du sport, Oct 28, 2005
Methods Fifteen volunteers participated in each experiment and were seated comfortably on a chair... more Methods Fifteen volunteers participated in each experiment and were seated comfortably on a chair behind a table in a darkened room. The right forearm had to be put on a lever that could freely rotate in the horizontal plane and a shaft encoder recorded its position. The dynamic display was a random-dot kinematogram, created in MATLAB, using the Psychophysics Toolbox extensions (Brainard, 1997; Pelli, 1997), and materialized as a black rectangle (117cm x 119cm) continuously filled with the total number of 700 dots. It ...
The contribution of texture to the perception of slant and curvature was studied in two experimen... more The contribution of texture to the perception of slant and curvature was studied in two experiments in which we collected judgments of human subjects by means of probe adjustment. For the slant-perception experiment, our stimuli consisted of flat surfaces receding away from the subject, while for the curvature experiment we used surfaces depicting half-elliptic cylinders whose major semi-axes pointed towards the subject. Both types of stimuli were generated under perspective projection with purpose written software ...
Abstract We investigated the influence of the perceived 3D-orientation of planar elliptical shape... more Abstract We investigated the influence of the perceived 3D-orientation of planar elliptical shapes on the perception of the shapes themselves. Ellipses were projected onto the surface of a sphere and subjects were asked to indicate if the projected shapes looked as if they were a circle on the surface of the sphere. The image of the sphere was obtained from a real,(near) perfect sphere using a highly accurate digital camera (real sphere diameter 40 cm; camera-to-sphere distance 320 cm; for details see Willems et al., Perception 29, S96, ...
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