PURPOSE To measure achromatic spatial contrast sensitivity in patients with anisometropic amblyopia under conditions favoring inferred parvocellular (PC) or magnocellular (MC) pathway mediation. METHODS Fourteen anisometropic amblyopes (VA amblyopic eye 6/12 or lower; better eye greater than 6/7.5) and 10 age-matched, nonamplyopic controls (VA 6/6) participated. Foveal spatial contrast sensit...

A plaid is a combination of two gratings whose orientations are orthogonal to each other with the same or similar contrasts. We used plaid patterns as stimuli to investigate the mechanisms underlying the detection of a plaid to understand how the visual system combines information from orientation-selective channels. We used a masking paradigm in which an observer was required to detect a targe...

With luminance gratings, psychophysical thresholds for detecting a small increase in the contrast of a weak 'pedestal' grating are 2-3 times lower than for detection of a grating when the pedestal is absent. This is the 'dipper effect'--a reliable improvement whose interpretation remains controversial. Analogies between luminance and depth (disparity) processing have attracted interest in the e...

It is well established that the visual system is sensitive to the global structure--or "form"--of objects defined exclusively by spatial or motion cues, but it remains unclear how form perception combines spatial and motion cues if these are presented concurrently. In the present study, we introduce a novel class of stimuli where spatial-form and motion-form can be superimposed and manipulated ...

We studied lateral interactions in the periphery by measuring how contrast discrimination of a peripheral Gabor patch is affected by flankers. In the psychophysical experiments, two Gabor targets appeared simultaneously to the left and right of fixation (4 degrees eccentricity). Observers reported which contrast was higher (spatial 2-alternative-forced-choice). In different conditions, Gabor fl...

Target threshold vs. pedestal contrast (TvC) functions for a vertical and a concentric target were measured on a vertical, a horizontal, a plaid or a concentric Gabor pedestal. All patterns had Guassian envelopes. All except one of the TvC functions had a dipper shape, that is, the target threshold first decreased and then increased with the pedestal contrast. The TvC function for a vertical ta...

The strong radial electric field in a subsonic tokamak pedestal modifies the neoclassical ion parallel flow velocity, as well as the radial ion heat flux. Existing experimental evidence of the resulting alteration in the poloidal flow of a trace impurity is discussed. We then demonstrate that the modified parallel ion flow can noticeably enhance the pedestal bootstrap current when the backgroun...

Toward mid-infrared (mid-IR) silicon microphotonic circuits, we demonstrate broadband on-chip silicon structures, such as: (i) straight and bent waveguides and (ii) beam splitters, utilizing an air-clad pedestal configuration which eliminates the need for typical mid-IR-lossy oxide cladding. We illustrate a sophisticated fabrication process that can create high-quality pedestal structures in cr...