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From: wise@cal-unix.UUCP
Newsgroups: net.general
Subject: Are you seeing pink walls?
Message-ID: <153@cal-unix>
Date: Fri, 9-Dec-83 11:53:22 EST
Article-I.D.: cal-unix.153
Posted: Fri Dec  9 11:53:22 1983
Date-Received: Sun, 11-Dec-83 01:34:15 EST
Organization: CALCULON BC#1, Rockville, MD.
Lines: 34

An interesting item appeared in the January, 1984 issue of the magazine
"Family Circle" on page 110.  The item was attributed to "The New England
Journal of Medicine", Vol 309, page 315.  The title in "Family Circle" was
"Computer Aftereffect - Not to Worry".  The text of the item follows.
While it specifically mentions personal computers, it seems clear that
it applies to any green on white VDU.

    A vivid visual illusion produced by working with a personal computer
    could be worrisome, but need not be.  Northwestern University
    researchers, who experienced the illusion, relate what happened to
    them:  After a session at the machine, which has a video display
    presenting luminous green characters on a dark backround, ordinary
    white letters and lines on contrasting backround appeared pink, and a
    pink fringe could be seen on sheets of white paper or white walls.
    Report Dr.  Mark J.  Greenwald and colleagues: "The pink aftereffect,
    which may persist for a day or longer, is a normal nervous system
    adaptation response.  While the response is harmless and never
    permanent, it could alarm anyone who hasn't heard of it, and
    physicians who are unaware of it could mistake it for a hysterical
    symptom or manifestation of neurological disease."

So now you know why the clothes you put on right after a session at the
terminal don't match.

I wonder if the reason that the color is pink is because green is yellow
and blue combined, i.e. white minus red.  Anyone out there know?  I assume
that this sort of problem has been encountered previously in some other
situation.


Rick Wise
seismo!rlgvax!cal-unix!wise