Visual perceptual learning (VPL) with younger subjects is associated with changes in functional a... more Visual perceptual learning (VPL) with younger subjects is associated with changes in functional activation of the early visual cortex. Although overall brain properties decline with age, it is unclear whether these declines are associated with visual perceptual learning. Here we use diffusion tensor imaging to test whether changes in white matter are involved in VPL for older adults. After training on a texture discrimination task for three daily sessions, both older and younger subjects show performance improvements. While the older subjects show significant changes in fractional anisotropy (FA) in the white matter beneath the early visual cortex after training, no significant change in FA is observed for younger subjects. These results suggest that the mechanism for VPL in older individuals is considerably different from that in younger individuals and that VPL of older individuals involves reorganization of white matter.
Age-related declines in vision are well documented in the literature. In the present study we exa... more Age-related declines in vision are well documented in the literature. In the present study we examined whether changes in spatial or temporal integration contribute to this decline. Younger (mean age of 21) and older (mean age of 745) subjects were asked to identify 2D shapes based on kinetic occlusion information-the accretion and deletion of texture during motion. The results of the first experiment indicated age-related decrements in spatial but not temporal integration. In the second experiment we manipulated the lifetime of motion stimuli to more directly examine temporal integration. The results indicated no differential effect of age on temporal integration. The results considered together suggest age related changes in recovering 2D shape from occlusion are the result of spatial but not temporal integration. Age-related changes in neural inhibition and ACh for regulating spatial integration are proposed as possible mechanisms for this decline.
Previous research has shown that a linear-trajectory collision event (i.e., collision between a m... more Previous research has shown that a linear-trajectory collision event (i.e., collision between a moving object and an observer) is specified by objects that are expanding and maintain a constant bearing (the object location remains constant in the visual field). In the present study we examined the optical information for detecting a collision event when the trajectory was of constant curvature. Under these conditions, a collision event is specified by expansion of an object and a constant rate-of-bearing change. Three experiments were conducted in which trajectory curvature and display duration were varied while maintaining time-to-contact, speed, and initial image position of the collision objects. Results indicate that collision detection performance decreased with an increase in trajectory curvature and decreased with a decrease in display duration, especially for highly curved trajectories. In Experiment 3 we found that the presentation of constant rate-of-bearing change in non-collision stimuli resulted in an increase in the false alarm rate. These results demonstrate that observers can detect collision events on curved trajectories, and that observers utilize bearing change information.
Visual perceptual learning (VPL) with younger subjects is associated with changes in functional a... more Visual perceptual learning (VPL) with younger subjects is associated with changes in functional activation of the early visual cortex. Although overall brain properties decline with age, it is unclear whether these declines are associated with visual perceptual learning. Here we use diffusion tensor imaging to test whether changes in white matter are involved in VPL for older adults. After training on a texture discrimination task for three daily sessions, both older and younger subjects show performance improvements. While the older subjects show significant changes in fractional anisotropy (FA) in the white matter beneath the early visual cortex after training, no significant change in FA is observed for younger subjects. These results suggest that the mechanism for VPL in older individuals is considerably different from that in younger individuals and that VPL of older individuals involves reorganization of white matter.
Age-related declines in vision are well documented in the literature. In the present study we exa... more Age-related declines in vision are well documented in the literature. In the present study we examined whether changes in spatial or temporal integration contribute to this decline. Younger (mean age of 21) and older (mean age of 745) subjects were asked to identify 2D shapes based on kinetic occlusion information-the accretion and deletion of texture during motion. The results of the first experiment indicated age-related decrements in spatial but not temporal integration. In the second experiment we manipulated the lifetime of motion stimuli to more directly examine temporal integration. The results indicated no differential effect of age on temporal integration. The results considered together suggest age related changes in recovering 2D shape from occlusion are the result of spatial but not temporal integration. Age-related changes in neural inhibition and ACh for regulating spatial integration are proposed as possible mechanisms for this decline.
Previous research has shown that a linear-trajectory collision event (i.e., collision between a m... more Previous research has shown that a linear-trajectory collision event (i.e., collision between a moving object and an observer) is specified by objects that are expanding and maintain a constant bearing (the object location remains constant in the visual field). In the present study we examined the optical information for detecting a collision event when the trajectory was of constant curvature. Under these conditions, a collision event is specified by expansion of an object and a constant rate-of-bearing change. Three experiments were conducted in which trajectory curvature and display duration were varied while maintaining time-to-contact, speed, and initial image position of the collision objects. Results indicate that collision detection performance decreased with an increase in trajectory curvature and decreased with a decrease in display duration, especially for highly curved trajectories. In Experiment 3 we found that the presentation of constant rate-of-bearing change in non-collision stimuli resulted in an increase in the false alarm rate. These results demonstrate that observers can detect collision events on curved trajectories, and that observers utilize bearing change information.
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Papers by Rui Ni