PubMed · 10124863
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G J Bailey. 1993. Three-dimensional imaging in microsurgery.. https://pubmed.ncbi.nlm.nih.gov/10124863/
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A 2IFC paradigm was used to measure speed discrimination thresholds for pairs of Gabor patches. When one of these patches was phenomenally placed over an illusory surface (IS), we observed higher thresholds relative to control conditions without ISs. Additional controls demonstrated that this effect was due to the placement of the patch on a different phenomenal depth plane rather than to the mere presence of an IS. We conclude that (i) ISs can affect the long-range integration of local motion signals, and (ii) long-range motion integration obeys a coplanarity principle.
Self-motion through a three-dimensional array of objects creates a radial flow pattern on the retina. We superimposed a simulated object moving in depth on such a flow pattern to investigate the effect of the flow pattern on judgments of both the time to collision (TTC) with an approaching object and the trajectory of that object. Our procedure allowed us to decouple the direction and speed of simulated self motion-in-depth (MID) from the direction and speed of simulated object MID. In Experiment 1 we found that objects with the same closing speed were perceived to have a higher closing speed when self-motion and object-motion were in the same direction and a lower closing speed when they were in the opposite direction. This effect saturated rapidly as the ratio between the speeds of self-motion and object-motion was increased. In Experiment 2 we found that the perceived direction of object-MID was shifted towards the focus of expansion of the flow pattern. In Experiments 3 and 4 we found that the erroneous biases in perceived speed and direction produced by simulated self-motion were significantly reduced when binocular information about MID was added. These findings suggest that the large body of research that has studied motion perception using stationary observers has limited applicability to situations in which both the observer and the object are moving.
PURPOSE: To evaluate stereoscopic visual evoked potentials (S-VEP) in normal controls and in patients with glaucomatous optic nerve damage. METHODS: Computer-generated dynamic random-dot stereograms were used to elicit cortical visual evoked potentials using wireless electric liquid crystal shutter glasses. Normal subjects (n=22) and patients with glaucoma (n=22) were investigated using five different disparities from 9 to 40 arc min. Statistical dependency of measurements with different stimulus at identical patients was adjusted for. RESULTS: Peak times of onset and offset response of S-VEP can be significantly delayed in glaucomas. A general linear regression model confirmed that differences between patients and normals depend on disparity. S-VEP onset shows no significant difference between controls and glaucomas at 9 arc min disparity. At high disparities, however, peak time of the onset response was significantly (p<0.01) delayed in glaucomas when compared with normals (normals: 125.8+/-13 ms, glaucomas: 148.2+/-25.6 ms at 40 arc min). CONCLUSIONS: Visual evoked potential elicited by the onset of a random-dot stereogram can be used for objective measurement of stereoacuity in a clinical setting. Differences between controls and glaucomas in high and low disparities could indicate a stereo-specific deficit in glaucoma.