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From: leichter@yale-com.UUCP
Newsgroups: net.micro
Subject: Re: More keyboard bogosity On the subject of cursor keys, mice & men:
Message-ID: <1700@yale-com.UUCP>
Date: Sat, 2-Jul-83 08:53:11 EDT
Article-I.D.: yale-com.1700
Posted: Sat Jul  2 08:53:11 1983
Date-Received: Sun, 3-Jul-83 01:03:09 EDT
References: utcsrgv.1658
Lines: 29

Yes, the eye-tracking stuff is real, although I don't think it's all that widely
used.  The hardware involved is an infra-red laser and detector set mounted on
the frame of a set of glasses or goggles; an infra-red beam is bounced off the
eyeball.  Here my knowledge of the details fades out; presumably, the beams
aimed at the pupil aren't bounced back nearly as strongly as those aimed else-
where.  THe technology involved is well-understood and often used in psych
labs.

Yes, of course, eye movements are a problem.  Eye-tracking motion is nothing
like linear - it is done is continuous bursts of motion (called saccades [sp?]).
At the very least, the system has to ignore eye position DURING saccades.
What is actually done is to require the user to stare intently at the target
for a substantial amount of time - substantial being with respect to the amount
of time the gaze normally stays in one spot, which isn't very long.  Just to
be sure, some auxilliary input would presumably be used to actually trigger
the action involved - so you don't have pilots inadvertently shooting all
their rockets at the moonrise.

There is a great tale about such a system that was put into fighters for a
while.  It triggered the emergency escape system; there was a big red cross
pointed down on the floor beside the pilot - where he would not normally
look.  If you gazed at the cross for "a while", bingo, off into the wild blue
yonder in your ejection seat.  Now think about the situation:  You are going
to spend HOURS in the cockpit, and off there are your left is this big red
cross that you MUST NOT LOOK AT....  Sure enough, no one could resist.  The
system was abandoned - a nice object lesson in the importance at considering
the human being in your "technologically leading-edge" system.
							-- Jerry
				decvax!yale-comix!leichter leichter@yale