From: bro@eunomia.rice.edu (Douglas Monk)
Subject: Re: Screen design considerations for color blindness
Date: Wed, 21 Aug 91 19:21:49 GMT
Message-ID: <1991Aug21.192149.27096@rice.edu>
Organization: Rice University, Houston


In article <1991Aug16.184039.14674@cbnewsi.cb.att.com> dak1@cbnewsi.cb.att.com (darren.a.kall) writes:

>impairment: physical condition, with a subcomponent: cause.
>	eg. Color-vision limitation due to lack of cone development.
>disability: functional condition, operationally defined.
>	eg. Unable to distinguish blue from yellow.
>handicap: A mostly emotional label attached to a person rather than
>	the condition, wholely unnecessary since it exists in the 
>	minds and opinions of others and not in the physical or
>	functional level. eg. Color blind.

When I was small, a doctor diagnosed me with what he claimed was the single
most common physical disability. The technical name escapes me (I *was* less
than 6 at the time :-), but the description and test for it is fairly simple:
the lowermost tendons (at the first joint == knuckle) influence each other so
that they do not operate in isolation. If I bend a finger at the knuckle, the
fingers on either side also bend at their knuckles involuntarily. (Resistance
brings great pain.)  For example, if I bend my little finger to touch the base
of the thumb on that hand, my ring finger points at right angles to the back of
my hand, my middle finger point at about 45 degrees, and my index finger at
about 30 degrees: and that is if I strain until it hurts.

The test for the condition: join your index and middle fingers together and
point them, aligning them with the back of your hand.  Now curl your little and
ring fingers until the fingertips touch your palm (and make sure the knuckles
bend: some of you will have to touch the *base* of the palm to do that, lucky
stiffs!) Did your index and middle fingers deflect? There is a range that is
considered acceptable, and beyond that, you are considered to have this
condition. In my case, my little finger and ring finger were perpetually curved
inward when I was diagnosed. Surgery or exercise were the only options, and
they thought I was too young to do the exercises. HA! :-) Nearly wore my
fingers off, but I got my hands to the state where surgery was no longer
considered necessary.

Now, this is unarguably an impairment and can even be considered a disability :
I can't bend my fingers at will into certain specific positions, after all. I
never considered it a handicap : I can type 60 words a minute, my hands look
perfectly normal (unless you force me to bend my fingers at the knuckle, and
then the grimace of pain on my face would probably make you overlook what my
fingers looked like :-). OK, so I can't be a Balinese dancer, and I speak
American Sign Language with an accent. I never felt like I had a handicap.

Then I went to the last SIGCHI conference and played on the Boeing Virtual
Reality demonstration. They put a 3-D projection helmet on me and put a
data-glove on my hand to read hand signals as commands.  Throughout my allotted
time, I had trouble getting the system to respond to my commands, and I simply
*could not* fly backwards.  My hand hurt quite badly, too, but I couldn't
figure out why. It wasn't until afterward, when I was walking away and was
suddenly hit by Virtual Reality Readaptation Vertigo (I was *fine* in VR, but
got dizzy back in the real world, but that's another handicap :-) and had to
sit down for a few minutes that I replayed the experience in my mind and
figured it out: the data-glove was reading the bending angle of the *knuckles*,
and the hand signal for reverse was to point the index and middle fingers and
bend the little and ring fingers' knuckles! No wonder my hand hurt. The system
saw my best attempts at the gesture as a closed fist. I had a virtual handicap!

I just did a spot check: of five people, four showed minor signs of the
condition, but two make the stop gesture acceptably. The other two could not.
This is 20%. The figure my long-ago doctor gave was 30%. But this gesture is
almost a standard now!

Moral one of the story: *always* let your users customize their user interface.
A VR system where these gestures are hard coded would be *useless* to me (not
to mention painful). Even better, read the *second joint* rather than the
knuckle.  (Let people missing fingers or parts of fingers fend for themselves.
*irony intended!* See moral one again.)

Moral two of the story: be considerate of the handicapped. You may be
handicapped too, and just haven't found out where yet. The impatient comments
of the people who were waiting in line to use the Boeing Virtual Reality system
ring in my ears yet. I was sorry I couldn't go in reverse: I had to fly around
in a circle and come back every time instead - it took longer. In a very small
way, I came to feel something of what it must be like to have a more serious
handicap. It isn't so bad, except for dealing with the normies.

Doug Monk (bro@rice.edu)

Disclaimer: These views are mine, not necessarily my organization's.


Disclaimer: These views are mine, not necessarily my organization's.