Re: More stuff on colours

On Tue, 19 Oct 2004 23:27:51 +0200, Henrik Theiling <theiling@...> wrote:
>
> Jörg Rhiemeier <joerg_rhiemeier@...> writes:
> > If they have words for `red' and `green', they are likely also to
> > have a word for `yellow'.  And what regards eye defects: No, anyone
> > who can see red and green can also see yellow, since it is red+green.
>
> But this is only true if both red and green receptors react to yellow
> light as human colour receptors do.  If not, *real* yellow would be
> distinct from red+green, namely, invisible.
But there is no wavelength of light that is perceived as "yellow" by
normally-sighted people: the point is that yellow light is made up of
several wavelengths (prototypically by at least one wavelength that's
red and one that's green). So as long as a given receptor responds to
red light, I'd expect it to do so whether that is the only light
falling into the eye (e.g. a laser) or whether it's part of a greater
spectrum (e.g. white or yellow light).

On the other hand, if their brain doesn't mix colours, a yellow light
might be perceived as being "both red and green" rather than as a
separate colour -- but then a word for "white" doesn't make sense to
me, since it should be perceived as "all of red and green and blue" by
the same logic.

Cheers,
--
Philip Newton <philip.newton@...>

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