Short-wave cone signal in the red-green detection mechanism.
Previous work shows that the red-green (RG) detection mechanism is highly sensitive, responding to equal and opposite long-wave (L) and middle-wave (M) cone contrast signals. This mechanism mediates red-green hue judgements under many conditions. We show that the RG detection mechanism also receives a weak input from the short-wave (S) cones that supports the L signal and equally opposes M. This was demonstrated with a pedestal paradigm, in which weak S cone flicker facilitates discrimination and detection of red-green flicker. Also, a near-threshold +S cone flash facilitates detection of red flashes and inhibits green flashes, and a near-threshold -S cone flash facilitates detection of green flashes and inhibits red flashes. The S contrast weight in RG is small relative to the L and M contrast weights. However, a comparison of our results with other studies suggests that the strength of the absolute S cone contrast contribution to the RG detection mechanism is 1/4 to 1/3 the strength of the S contribution to the blue-yellow (BY) detection mechanism. Thus, the S weight in RG is a significant fraction of the S weight in BY. This has important implications for the 'cardinal' color mechanisms, for it predicts that for detection or discrimination, the mechanisms limiting performance do not lie on orthogonal M-L and S axes within the equiluminant color plane.
Stromeyer
C F
CF
Division of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA. charles@stokes.harvard.edu
Chaparro
A
A
Rodriguez
C
C
Chen
D
D
Hu
E
E
Kronauer
R E
RE
D003118:Color Perception / Q000502:physiology*; D004056:Differential Threshold; D005425:Flicker Fusion; D006801:Humans; D008297:Male; D008433:Mathematics; D011594:Psychometrics; D017949:Retinal Cone Photoreceptor Cells / Q000502:physiology*