For a tritanope, is the Copunctal point closer to 400nm or 700nm?

The correct answer is that for a tritanope, the copunctal point is closer to 400 nm. Tritanopes are individuals who have a deficiency in the blue cone photoreceptors, leading to a form of color vision deficiency where they struggle to perceive blue-violet hues.

The copunctal point is defined as the wavelength at which the monochromatic lights of different colors have the same perceived brightness for the individual. In individuals with normal color vision, this point typically falls around the middle of the visible spectrum, closer to 550 nm. However, for tritanopes, who lack blue photoreceptor function, the perception shifts towards shorter wavelengths, which means they perceive these shorter wavelengths (like those closer to 400 nm) as relatively brighter in comparison to the longer wavelengths (like those near 700 nm or 600 nm). Therefore, the copunctal point for a tritanope aligns more closely with the blue end of the spectrum, around 400 nm.

This understanding is crucial when considering how different types of color vision deficiencies affect color perception, helping to clarify the unique visual experiences of tritanopes.