Using an 8 mm pupil, 2AFC-method, and 2 x 2 deg2 grating at 2 c/deg we measured contrast sensitivity as a function of integrated radiance for a series of interference filters with peak wavelengths at 400-700 nm. Irrespective of the radiance level, contrast sensitivity was highest when wavelength was at and around 550 nm. It decreased towards longer and shorter wavelengths, reflecting the variat...

We examined visual estimation of surface roughness using random, computer-generated, three-dimensional (3D) surfaces rendered under a mixture of diffuse lighting and a punctate source. The angle between the tangent to the plane containing the surface texture and the direction to the punctate source was varied from 50 to 70 deg across lighting conditions. Observers were presented with pairs of s...

In a two-frame apparent motion display, a test grating was displaced horizontally or vertically in the presence of an inducer of which component gratings made up expanding/contracting or rotational motion as a whole. In the first experiment, we demonstrated that motion assimilation did occur for the test accompanied by the two-dimensional motion of the inducer. In the second experiment, we show...

Studies of second-order visual processing have primarily been concerned with understanding the mechanisms for detecting spatiotemporal variations in such attributes as contrast, orientation, spatial frequency, etc. Here, we have examined the orientation characteristics of second-order processes using bandpass noise whose Fourier energy is sinusoidally modulated across orientation, rather than a...

We presented two tasks, spatial interval discrimination and displacement detection, simultaneously in the same location at various eccentricities. The subject was to solve (i) only the spatial interval task; (ii) only the displacement task; or (iii) both tasks simultaneously. With 500 msec stimulus duration, and using the method of spatial scaling, the E2 value (the eccentricity at which stimul...

Stereothresholds are elevated by vergence constant error (fixation disparity), vergence noise, or both. This study investigated the separate and combined effects of simulated vergence constant error and variability on stereothresholds in four normal observers. Targets were 30 arc min bright vertical lines presented separately to the two eyes for 150 ms in darkness. Vergence constant error, simu...

We studied the change of spatial and temporal response properties for cat horizontal (H-) cells during prolonged dark adaptation. H-cell responses were recorded intracellularly in the optically intact, in vivo eye. Spatial and temporal properties were first measured for light-adapted H-cells, followed by a period of dark adaptation, after which the same measurements were repeated. During dark a...

Previous work has shown that detectability of motion is better when the observer knows ahead of time the direction of that motion ("certainty") than when he does not know the direction ("uncertainty"). We now report attempts to reduce this performance decrement associated with direction uncertainty. In these experiments, a briefly flashed, oriented line cued the observer to the direction of mot...

PURPOSE To investigate saccade dynamics as a function of age to determine whether they follow the pattern of development and decline predicted by Weale's model of aging. METHODS One hundred ninety-five participants between the ages of 3 and 86 years made visually guided horizontal prosaccades ranging in size from 1 degrees to 60 degrees in response to dot stimuli. Eye movements were recorded ...

We investigated the relationship between attention and perceived duration of visual events with a double-task paradigm. The primary task was to discriminate the size change of a 2 degree circle presented 10 degrees left, right, above, or below fixation; the secondary task was to judge the temporal separation (from 133 ms to 633 ms) of two equiluminant horizontal bars (10 deg x 2 deg) briefly fl...