Supersaturation in the peripheral retina.

Foveal and peripheral hue-scaling data were obtained for a 1° foveal stimulus and a 3° stimulus presented at 10° retinal eccentricity under both bleach (reducing rod input) and no-bleach (permitting rod input) conditions. Uniform appearance diagrams (UADs) were generated from the data. Peripheral stimuli appeared more saturated than foveal stimuli (i.

Color appearance at ±10° along the vertical and horizontal meridians.

Hue-scaling data were collected from three observers using the "4+1" color-naming procedure for circular (0.25°-5°), monochromatic (440-660 nm) stimuli. Stimuli were presented at ±10° along the vertical and horizontal meridians under conditions chosen to include both rod and cone signals (no bleach) and to minimize rod contribution (bleach).

Middle- and long-wavelength discrimination declines with rod photopigment regeneration.

Hue-discrimination functions were derived from hue-naming data (480-620 nm, 20 nm steps) obtained in 4 min intervals from 4 min to 28 min postbleach at 10° temporal retinal eccentricity. Hue-naming data were also obtained in the fovea. Hue-discrimination functions derived at the 4, 8, and 12 min intervals were very similar to those derived in the fovea.

Unique hue loci differ with methodology.

Background: Studies investigating the effect of rods on unique hue loci in the peripheral retina generally obtain measures at two time points associated with the dark adaptation function - the cone plateau and the rod plateau. In comparison, this study used a color-naming procedure to identify the loci of unique green and unique yellow as a function of time associated with the entire dark adaptation function. The unique hue loci derived by this procedure were then compared to those obtained directly with a staircase procedure.

Neural generators of ERPs linked with Necker cube reversals.

Multistable perception occurs when a single physical stimulus leads to two or more distinct percepts that spontaneously switch (reverse). Previous ERP studies have reported reversal negativities and late positive components associated with perceptual reversals. The goal of the current study was to localize the neural generators of the reversal ERP components in order to evaluate their correspondence with previous fMRI results and to better understand their functional significance.

Chromatic perceptive field sizes measured at 10 degrees eccentricity along the horizontal and vertical meridians.

The different hemifields in the retina are known to vary in photoreceptor density as well as in the number of photoreceptors converging onto one ganglion cell. The effect of these differences among the retinal hemifields at 10 degrees retinal eccentricity was investigated using a color-naming procedure to derive perceptive field sizes for the hue terms of blue, green, yellow, and red. Color-naming data were obtained under two conditions: (1) after a bleach condition, chosen to minimize rod contribution, and (2) after 30 min dark adaptation, chosen to maximize rod contribution.

Early top-down influences on bistable perception revealed by event-related potentials.

A longstanding debate exists in the literature concerning bottom-up vs. top-down influences on bistable perception. Recently, a technique has been developed to measure early changes in brain activity (via ERPs) related to perceptual reversals (Kornmeier & Bach, 2004).

Electrophysiological correlates of perceptual reversals for three different types of multistable images.

Electrophysiological recordings were made in 21 observers to investigate whether differences in signature components (P1, N1, selection negativity [SN]) would be revealed during perceptual reversals of three different multistable figures. Using a lattice of Necker cubes as a stimulus, J. Kornmeier and M.

Effect of stimulus intensity on the sizes of chromatic perceptive fields.

The effects of intensity on chromatic perceptive field size were investigated along the horizontal meridian at 10 degrees temporal eccentricity by manipulating stimulus intensity from 0.3 to 3.3 log trolands.

Chromatic perceptive field sizes change with retinal illuminance.

The effect of retinal illuminance (0.3-3.3 log td) on chromatic perceptive field size was investigated at 10 degrees eccentricity along the horizontal meridian of the temporal retina.

A new look at the Bezold-Brücke hue shift in the peripheral retina.

Experiments were conducted with a bipartite field to better understand the Bezold-Brücke hue shift in the peripheral retina. The first experiment measured hue shift in the fovea and at 1 degrees and 8 degrees along the horizontal meridian of the nasal retina for nominal test wavelengths of 430, 450, 490, 520 and 610 nm. Peripheral measurements were obtained under two adaptation conditions: after 30 min dark adaptation and following a rod-bleach.