Chromatic content of spectral lights.

Using three novel formats, we compare four estimates of the spectral sensitivity of the opponent stage channels: a Linear Model, Jameson and Hurvich's [Journal of the Optical Society of America, 45, 546-552 (1955)] hue cancellation sensitivities, Gordon and Abramov's [Optical Society of America Technical Digest Series, 15, 12-15 (1987)] hue scaling, and hue matching. The three formats are: the spectrum locus in the opponent equiluminant plane, null lines in the CIE XYZ chart and response functions for unique hues. All sensitivities show departures from the Linear Model and from each other.

Perceptual correlates of magnocellular and parvocellular channels: seeing form and depth in afterimages.

The chromatic and achromatic channels of psychophysical models do not map simply onto the parvocellular and magnocellular channels of electrophysiology because the parvo channel carries both chromatic and achromatic signals. If vision of stabilized images be mediated by the parvo channel, then this channel mediates form and depth percepts.

Spectral sensitivity for flicker and acuity criteria.

Different channels in the visual system mediate the detection of flicker and the detection of high spatial frequencies. The magnocellular channel is optimized for flicker detection, whereas the parvocellular channel is optimized for color vision and spatial resolution. The spectral sensitivity of the magnocellular (flicker) channel is obtained by combining cone inputs in the ratio R/G = 5/3; the spectral sensitivity of the parvocellular channel is obtained with the ratio R/G = 2/3.

Flicker photometry and achromatic-channel structure.

It is widely assumed that the near-perfect additivity of heterochromatic flicker photometry implies the existence of an achromatic channel in the visual system, which accurately sums R- and G-cone signals. For flicker photometry to be additive, the channel that detects the flicker stimulus need not add cone signals.

The spatiotemporal properties of the r-g X-cell channel.

Analysis of the simple-opponent r-g receptive field of the X-channel shows that it is tuned to both high and low temporal frequencies, high and low spatial frequencies, and that its spectral sensitivity is both chromatic and achromatic.