This is a fascinating hypothesis and concept. But what puzzles me are a few things, such as:

  • Wouldn't a failure of X inactivation be more likely to result in tetrachromatism? (Two divergent sets of genes simultaneously expressed?)

  • Why would a four-color visual perception system be interpreted in the end by the brain at all differently? Wouldn't the brain simply compensate for the variations in post-processing?

  • As for testing the hypothesis, or trying to confirm or refute any perceptual advantages/disadvantages these women might have, the first thing I would think of would be to compare a sample of mothers of known color-blind sons with a random sample of women. Test as many aspects of visual perception and color perception as possible. Do they have a higher (or lower) incidence of design skills and talents than women in the normal sample?

    Or, go the other way and compare a selective sample of women who work in visual arts (interior designers, graphic designers, fashion designers, quilters, craftswomen, etc.) to a random female sample. Then conduct a possibly longitudinal study to detect any meaningful variation in the frequency of color blind sons between the two samples?