Protanopes and deuteranopes
(red-green dichromats) lack, respectively, long (L) or medium (M) wavelength-sensitive cones because of genetic factors (Neitz & Neitz, 2011).
The participants were divided into five groups: normals, deuteranomals, deuteranopes
, protanomals, and protanopes.
Similar to these cases are those of the deuteranopes
mentioned in footnote 7.
For example, a dog may literally see red (that is, what humans would call red) when looking at Garfield the cat, who seems orange to normal humans and who often looks yellow to deuteranopes
1) Protanopes and deuteranopes
are able to match all red-green mixture ratios.
are unable to distinguish red, yellow, and green when the brightness of all three colors is equal.
Protanopes have a normal M gene, whereas deuteranopes
have a normal L gene.
Those with colour vision defects see the spot differently; for example protanopes usually describe it as blue or dark because their red sensitivity is reduced, and most deuteranopes
cannot see the spot at all.
Hidden digit plates seem to work better for deuteranopes
than other colour deficient individuals but they have an overall sensitivity of only around 50%.
The neutral points for deuteranopes
, protanopes and tritanopes are around 498nm, 492nm and 569nm respectively.
Out of these 8 subjects, 5 subjects were deuteranope
and 3 subjects were protanope.
Table 1 Examples of colours that might be confused by colour deficient observers Colour deficiency Examples of colours that might be confused Protanope Blue--green/white/red Pale blue/purple/magenta Red/orange/yellow/green Deuteranope
Purple/Grey/greenish blue-green Red/orange/yellow/green Red/brown, green/brown Tritanope Yellow/white Violet/yellow-green Red/red-purple