Newsgroups: rec.arts.sf.written,sci.lang
Path: cantaloupe.srv.cs.cmu.edu!rochester!rutgers.rutgers.edu!cbgw3.lucent.com!newshub.netnews.att.com!ulysses!akalice!news
From: Peter Shor <shor@research.att.com>
Subject: Re: Colors (was: Dialects (Was Re: Shakespeare's Future))
X-Nntp-Posting-Host: fry.research.att.com
Content-Type: text/plain; charset=us-ascii
Message-ID: <331AEE30.41C6@research.att.com>
Sender: news@research.att.com (netnews <9149-80593> 0112740)
Content-Transfer-Encoding: 7bit
Organization: AT&T Labs
References: <5d8a07$nma@darla.visi.com> <5ett24$fdo@agate.berkeley.edu> <5f346d$hfi@halley.pi.net> <01bc252f$68d966e0$c8203fce@brianwi.halcyon.com> <5fa62m$17c@netsrv2.spss.com> <857294286snz@kenjo.demon.co.uk> <5fd61g$gv2@idiom.com>
Mime-Version: 1.0
Date: Mon, 3 Mar 1997 15:28:48 GMT
X-Mailer: Mozilla 3.0 (X11; I; IRIX64 6.2 IP19)
Lines: 30

Olivier Cremel wrote:
> 
> Jo Walton (Jo@kenjo.demon.co.uk) wrote:
> : But can anyone _really_ not think turquoise is sufficiently distinct a shade
> : to be worthy of a separate name? (I love blue. I don't like turquoise at
> : all.) Are there tests for whether one is tetrachromatic as opposed to
> : merely paying attention?
> 
> I find this whole matter of tetrachromaticity strange. Aren't three
> wavelength enough to exactly describe any wavelength ? Isn't that
> the very principle of painting, photography and TV ? What good could
> a fourth wavelength do ? None I would think, not even to get more
> nuances, since they are already completely defined by three wavelength.
> 
> Olivier.

The only reason that three wavelengths are enough to describe any
COLOR is because we have three different kinds of color receptors
in our eyes (red, green, blue).  There are apparently two slightly
different variations of the red receptor, each sensitive to slightly
different wavelengths.  This means that some people see colors 
slightly differently (so two things which look like the same color to
some people will look somewhat different to other people.  There are
some people (mainly women --- it's on the X chromosone, which is also
why men have a much higher rate of red-green color blindness)
who have both versions of the red receptor, but in order to really
see tetrachromatically I think you'd have to have your neurons linked
up properly, and I don't know whether they are in these people.

Peter Shor
