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Biomedical subjects

C W Tyler

Publications and source records attributed to C W Tyler.

At least 181 records · Page 10Linked to original sources
PubMed1973

Steroscopic vision: cortical limitations and a disparity scaling effect.

The spatial limitations of stereoscopic vision were studied by using vertical line stimuli containing sinusoidal disparity variations such that different parts of the line appeared at different depths. Stimuli with a finer grain than about 3 cycles per degree did not elicit depth perception, even though the sinusoidal curvature was clearly visible monocularly. At low spatial frequencies of curvature, stereoacuity was limited to the same extent as the monocular sensitivity. The limiting disparity for Panum's fusional region and the upper depth limit are subject to a scaling effect in proportion to stimulus dimensions. The disparity scaling can be characterized by a fixed maximum angular difference between the parts of the stereoscopic half-images.

Depth Perception↗
PubMed1973

Periodic vernier acuity.

1. Sinusoidal curvature was produced in a vertical stimulus line generated on an oscilloscope screen. Sensitivity to sinusoidal curvature (periodic vernier acuity) was measured by the method of adjustment as a function of spatial frequency of the curvature.2. Sensitivity was maximal at about 3 c/deg and reduced steeply for both higher and lower spatial frequencies of curvature.3. Sensitivity at 10 degrees in the periphery was greatly reduced but showed very little low frequency reduction.4. The effect of number of cycles present was checked by reduction of the field size with spatial frequency such that a fixed number of cycles of the stimulus were visible. This procedure did not affect the decline in sensitivity at spatial frequencies below 0.3 c/deg but reduced sensitivity at higher spatial frequencies.5. The results were interpreted in terms of cortical orientation detectors. It is suggested that the low frequency sensitivity is limited by a fixed value for the maximum difference in orientation in the stimulus (i.e. 20 and 30' for the present subjects). The high frequency sensitivity was limited by grating acuity and required spatial integration of the stimulus information over about 2.5 degrees .

Discrimination, Psychological↗
PubMed1971

Stereoscopic depth movement: two eyes less sensitive than one.

Visual sensitivity to stimuli with sinusoidal movement was examined under a number of conditions of binocular stimulation. Sensitivity to stereoscopic movement in depth was reduced in comparison to that for monocular movement. The reduced sensitivity appeared to be due to the presence of stereoscopic depth movement, as opposed to stereoscopic stimulation, binocular movement, or fusion of the images.

Depth Perception↗