Here is a rebuttle from David harrell to Tim Cranmer's letter to this list.
-Brian
Dear Dr. Cranmer,
There appear to be two areas of confusion in regards to my proposal.
The first is the method of stimulation. You say that Smith Kettwell has
built a low resolution "mechanical" stimulator. This would be my last choice
of methods. In contrast, I am suggesting a high resolution (100,000+ picts
is easily obtainable) electric or laser sweep (operating from a cone shaped
emitter placed on the subjects back or scalp). This is the same method which
a conventional TV picture tube uses to light the picts located on the
screen-face area of the tube. The sensation I am attempting to produce is
that of a tickle or slight heat, corresponding with the lighted areas in the
picture. This "tickle sensation" might also be eventually produced by a
snugly worn pad embedded with an electrode grid array. Considering the
varying number of current types available, it is difficult for me to view
this as a serious impasse to the building of the first prototype.
Also, the fingertips, although more densely populated with nerve endings,
would not offer a large enough area for the necessary resolution. Giving the
current state of electronic technology, I am certain that such a tickle
sensation could be delivered to a dermal area in a variety of different
methods and intensities.
Secondly, there is the matter of interfacing the subject with a real-time
physical environment. For instance, imagine a mobile subject fitted with a
working portable device that was delivering the picture from a camera
(perhaps cap mounted) to an emitter pad covering as large an area of the back
as possible, with as many picts involved as would be useful to increase the
"resolution' of the image.
Now place this subject in an environment void of light, except for a line
guided path which the subject would begin to walk upon. Now suppose that
this path at some point has a low hanging lighted (white) limb (I don't wont
to appear cruel of flippant here, but this is necessary to make my point).
The first time the subject encountered the limb, there would be a
registration by the Feel-A-Vision system of a "white stripe" that would pass
across the "back pad emitter field" just before the subject was impeded by
the limb.
What I am saying is that eventually the subject will associate the passing of
the "white stripe" as a cognitive precursor to being struck by the limb, and
will duck. The rest is merely a matter of experience, learning to
distinguish shapes and details. But the key is to create conditions that
offer instant feedback in a real and physical space. This is the kind of
endeavor in which the human mind invariably excels to astonishing heights.
In the 1980s there was a conference in Hollywood, CA discussing an attempt to
implant a transmitter into the visual cortex (again delivering simple shapes
and letters to a stationary subject), but I consider an implant to the visual
cortex to be a clumsy, unnecessary, and less effective conduit to the brain.
Remember, adaptability is the strongest single resource of the brain. If a
useful orderly image is made available, the brain will tune in to it. The
only necessary ingredient to achieve effective results where human beings are
involved, seem to be determination and endurance. I expect there will be no
shortage of these elements.
Every version of this method, that I am aware of, has dealt with a stationary
subject. This scenario would not offer the kind of real-time feedback
necessary for the subject to begin adapting to the device, nor for the brain
to discover and correlate the relevance and usefulness of the area being
stimulated.
Assume that we have already built such a device, i.e. a moving picture is
being delivered to the back area of a subject in the form of a tickle or heat
image; if the subject does not proceed to interface with a real environment,
then I would not expect any learning, nor even cerebral discover of the area.
Putting such a devise on a stationary subject, would be like inventing a
parachute and then attempting to test it from the deck of a submarine.
Finally I am suggesting that if such a tickle image is made available to the
brain, that it is the natural business of the brain to recognize such an area
of two-dimensional data within a given feedback loop of real-time
information, this being complete analogous to the normal relationship between
the visual cortex and the rear portion of the inner eye surface (in effect
offering the visual cortex an "alternate retina"). It is the correlation
between the real world, and this new area of stimulation, that will achieved
the inevitable communication of a useful "picture".
Dr. Cranmer, my field is cognitive science, not creative writing nor
communication. I tried 12 years ago to convince someone (anyone) that this
would work, and failed. Given a modest staff and budget, I am certain that I
can build such a machine within one year, and have a subject playing tennis
within another year.
David Harrell
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