The optics of the eye focus an image of the world onto the retina which contains four types of photoreceptors: blue, green and red cones and a single type of rod. Experiments are being conducted to learn how the signals from the three cone photoreceptor types of the retina are organized and how the information about color is organized and processed by the early stages of the visual system. Conventional wisdom holds that information from photoreceptors is transmitted by two main visual pathways in the brain: one is sluggish and transmits information about color; the other is rapid and transmits information about intensity. The specific studies being conducted in this research project use flickering light of different colors and flicker interactions to address specific questions about the nature of these two visual pathways, as well as how their signals change when the visual system adapts to increasingly intense lights. This research is providing clear evidence that the early stages of the visual system are more complex than the prevailing psychophysical models suggest.
