Abstract
We examined the ability of observers to detect the 3D curvature of motion paths when binocular disparity and motion information were present. On each trial, two displays were observed through shutter-glasses. In one display, a sphere moved along a linear path in the horizontal and depth dimensions. In the other display, the sphere moved from the same starting position to the same ending position as in the linear path, but moved along an arc in depth. Observers were asked to indicate whether the first or second display simulated a curved trajectory. Adaptive staircases were used to derive the observers' thresholds of curvature detection. In the first experiment, two independent variables were manipulated: viewing condition (binocular vs. monocular) and type of curvature (concave vs. convex). In the second experiment, three independent variables were manipulated: viewing condition, type of curvature, and whether the motion direction was approaching or receding. In both experiments, detection thresholds were lower for binocular viewing conditions as compared to monocular viewing conditions. In addition, concave trajectories were easier to detect than convex trajectories. In the second experiment, the direction of motion did not significantly affect curvature detection. These results indicate the detection of curved motion paths from monocular information was improved when binocular information was present. The results also indicate the importance of the type of curvature, suggesting that the rate of change of disparity may be important in detecting curved trajectories.
Highlights
The perception of the 3D motion trajectory of objects is an important visual task
In the present study we examined the use of binocular information and changes in angular speed and angular size for determining the trajectory of moving objects on curved paths
Detection of 3D curved trajectories binocular information is used for the perception of motion in depth and suggest that binocular information may be important for the perception of curved motion paths
Summary
The perception of the 3D motion trajectory of objects is an important visual task. Accurately judging the 3D motion trajectory of objects is important for activities such as intercepting an object or catching a ball. In the temporally correlated stimuli, both sources of binocular information were available They found that the threshold to detect motion in depth was lower for the temporally uncorrelated stimuli as compared to temporally correlated stimuli, suggesting that the rate of change in binocular disparity was used to determine motion in depth while the IOVD was not useful. Shioiri et al (2000) used binocularly uncorrelated random dot kinematograms and found that observers were able to discriminate motion in depth at high contrast, providing support for the use of IOVD in judging motion in depth In addition to binocular information, the observer has available monocular information for determining the 3D trajectory of a moving object This information includes the change of angular speed and angular size of an object’s projection as it travels in depth. The results of this research indicate that observers are able to discriminate the direction of motion trajectories even when the direction and velocity of retinal image translation were removed as reliable cues
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