KnowraTetrachromacyLinked fromLinked fromThe 7 pages that link to Tetrachromacy, each with the reason it gives.All 7Compared with 7Color visionCompared with: More cone types than trichromacy, testing whether color space grows accordingly.MetamerismCompared with: A fourth cone splits metamers that three cones merge, refuting universality.TrichromacyCompared with: Some women carry a fourth cone opsin; the upper end of the receptor-count scale.Color matching (trichromacy)Compared with: Carrier women with a fourth cone type violate the three-primary rule, delimiting the theory.Photopic visionCompared with: It raises questions about how cone variation might expand color discrimination beyond typical trichromacy.Young–Helmholtz theoryCompared with: It tests whether the theory’s three receptor types describe every human visual system.DichromacyCompared with: It adds a fourth independent signal beyond dichromacy’s two.