Why do pre-employment color vision tests (Ishihara plates) use such similar color hues even for jobs where the colors are never that similar? In jobs I've worked (building maintenance, warehouse, manufacturing), the colors in use are very dissimilar: i.e. bright red versus bright green lights or solid black wires versus solid green wires versus solid white wires.
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They are testing for red/green color deficiency, which occurs in 8% of the male population.
The colors on the plates have nothing to do with the colors you will be working with on the job but, rather, they are designed so that men with this condition will give different answers to the plates then people with normal vision will give.
A red/green color deficient person would have a hard time telling a bright red verses bright green light apart....
Does this make sense to you?
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You wrote: "A red/green color deficient person would have a hard time telling a bright red verses bright green light apart"
Why not then have a test that just asks people to identify a bright red light, green light, blue light, yellow light, etc.? I realize that you aren't the inventor of this whole industry practice, so my intent isn't to put the pressure on you. However, I feel like using such muted, similar hues in the test would unfairly discriminate against people with very slight color vision deficiency. What if a candidate's color vision deficiency is bad enough that he can't pass the Ishihara test but he can easily differentiate bright colors that are very dissimilar, such as on a traffic stoplight? In that case, is it not plausible that the doctor administering the physical, especially not being a trained optometrist or ophthalmologist, would report that the patient is color blind and thus unqualified for the job? I realize that the patient could go to an eye professional for a more detailed examination, but most employers would just move on to the next candidate. How is the candidate protected from this sort of situation?