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From: eds@bunker.UUCP (Eric Schlesinger)
Newsgroups: net.followup
Subject: Re: Are you seeing pink walls?
Message-ID: <313@bunker.UUCP>
Date: Mon, 19-Dec-83 15:42:16 EST
Article-I.D.: bunker.313
Posted: Mon Dec 19 15:42:16 1983
Date-Received: Wed, 21-Dec-83 02:06:49 EST
References: cal-unix.153
Lines: 25

Not so long ago, the BBC (that's in England, folks) did a series
of Open University programs on such phenomena.  It seems that it
relates primarily to the organization of color receptors in
the human eye, and the fact that when stressed excessively they
fatigue rather rapidly.  This is the case when one stares at a typical
green phosphor for unduely long amounts of time.

Afterwards, the other receptors are out of balance (in terms of 
strength of reception).  So the brain receives an image which is more
heavily excited to the other colors; since it appears that there are
primarily red/green receptors, the green-induced fatigue produces a 
reddish aftereffect.  (Note that most color-blindness is oriented
towards red/green, and that part of a standard eye examination - the
ones I've had, anyway - uses red and green filters to compare visual
acuity.)

I'm sure there's more and more detailed information regarding this
sort of thing somewhere.  But the above was picked up on a half-hour
Open University show; of course, no one has ruled out that after 
staring at a CRT for hours one also has the tendency to drink
excessively which can *also* account for everything having a 
reddish tinge.

Eric Schlesinger
Bunker Ramo Information Systems (known to the trade as BRIS)