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Abstract:
Three cone types provide the input signals into our color vision. Their respective spectral sensitivities peak at wavelengths of about 430 nm (S-cones), 530 nm (M-cones) and 560 nm (L-cones). L- and M-cones comprise the vast majority of cone types in color-normal human retinae. The ratio between these two cone types — called the L/M-ratio – is found to vary considerably between 1 and 10.
We have recently developed a new method to determine the relative contribution of the three cone types to the perception of brightness in human observers (Teufel Wehrhahn, JOSA A, 17: 994–1006, 2000). This method provides a fast and robust procedure to determine cone contributions to perceived brightness and includes an estimate of L/M-ratios.
Here we report that color normal female and male observers have very different distributions of L/M-ratios. Specifically female observers show a distribution of L/M-ratios with two peaks, situated at low and high L/M-ratios, respectively. This is opposed to color normal male human observers, whose distribution was found to have only one peak at medium L/M-ratios.
We propose that this difference in distributions is due to a previously unknown genetic mechanism regulating the genesis of retinal cones.
