Abstract
“Cardinal” colors are reddish, greenish, bluish, yellowish, black and white; they are called cardinal because mechanisms underlying their perception emerge early in visual processing, in the retina. All other colors are called “non-cardinal” colors. A number of studies have shown evidence for separate non-cardinal mechanisms in the isoluminant color plane. However, it has been more difficult to show that there are separate non-cardinal mechanisms in the red-green/luminance or tritan/luminance color planes. This study tests the hypothesis that non-cardinal mechanisms may be weak due to a failure of Hebbian wiring. Hebbian wiring says that neurons that fire together wire together. Neurophysiological evidence has shown that the tritan signal is 30ms slower to reach the cortex than is the luminance signal, likely too long of a delay for Hebbian wiring to occur. The current study performs Hebbian conditioning by presenting a tritan grating 10, 20, 30, 40, or 50ms before a luminance grating, 500 times (in separate groups of subjects; also with a no conditioning control). This sequence has been shown to produce Hebbian conditioning in adult human subjects in other vision studies. The strength of non-cardinal mechanisms between tritan and luminance is measured by the threshold ratio to detect non-cardinal stimuli in their own (aligned) vs. orthogonal noise; separate underlying non-cardinal mechanisms are shown by a higher threshold in aligned noise. Data collection is on-going.