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We used fMRI to directly compare the neural substrates of three-dimensional (3-D) shape and motion processing for realistic textured objects rotating in depth. Subjects made judgments about several different attributes of these objects, including 3-D shape, the 3-D motion, and the scale of surface texture. For all of these tasks, we equated visual input,(More)
Two experiments were conducted to explore the potential effects of aging upon the perception and discrimination of speed. In the first experiment, speed difference thresholds were obtained for younger and older observers for a variety of standard speeds ranging from slow to fast. The second experiment was designed to evaluate the observers' ability to(More)
Three experiments are reported in which observers judged the three-dimensional (3-D) structures of virtual or real objects defined by various combinations of texture, motion, and binocular disparity under a wide variety of conditions. The tasks employed in these studies involved adjusting the depth of an object to match its width, adjusting the planes of a(More)
A single experiment investigated how younger (aged 18-32 years) and older (aged 62-82 years) observers perceive 3D object shape from deforming and static boundary contours. On any given trial, observers were shown two smoothly-curved objects, similar to water-smoothed granite rocks, and were required to judge whether they possessed the "same" or "different"(More)
In this study, we evaluated observers' ability to compare naturally shaped three-dimensional (3-D) objects, using their senses of vision and touch. In one experiment, the observers haptically manipulated 1 object and then indicated which of 12 visible objects possessed the same shape. In the second experiment, pairs of objects were presented, and the(More)
The ability of younger and older observers to perceive 3-D shape and depth from motion parallax was investigated. In Experiment 1, the observers discriminated among differently curved 3-dimensional (3-D) surfaces in the presence of noise. In Experiment 2, the surfaces' shape was held constant and the amount of front-to-back depth was varied; the observers(More)
There have been numerous computational models developed in an effort to explain how the human visual system analyzes three-dimensional (3D) surface shape from patterns of image shading, but they all share some important limitations. Models that are applicable to individual static images cannot correctly interpret regions that contain specular highlights,(More)
The ability of observers to perceive distances and spatial relationships in outdoor environments was investigated in two experiments. In experiment 1, the observers adjusted triangular configurations to appear equilateral, while in experiment 2, they adjusted the depth of triangles to match their base width. The results of both experiments revealed that(More)
Five experiments were designed to investigate visual speed discrimination. Variations of the method of constant stimuli were used to obtain speed discrimination thresholds in experiments 1, 2, 4, and 5, while the method of single stimuli was used in experiment 3. The observers' thresholds were significantly influenced by the choice of psychophysical method(More)
This study compared the sensory and perceptual abilities of the blind and sighted. The 32 participants were required to perform two tasks: tactile grating orientation discrimination (to determine tactile acuity) and haptic three-dimensional (3-D) shape discrimination. The results indicated that the blind outperformed their sighted counterparts (individually(More)