Yep, seems like good empirical support for Dennett's competing modules theory
of the brain.
Brent
On 2/3/2015 8:44 AM, Jason Resch wrote:
A vetrean of the Second World War, known only by his initials W.J.,
suffered from a severe case of epilepsy. Worse, medication could not stop his frequent
and incapacitating seizures. There was, however, another option: he could undergo a
radical and newly conceived brain surgery. The surgery would sever his /corpus
callosum/, the tight bundle of neural wiring that links the two hemispheres of one's
brain. It was thought that his seizures originated in one side of his brain and spread
to impair the other side. Severing the link would confine the seizure and prevent it
from impairing his entire brain. In 1961 W.J. elected to undergo this surgery and by all
accounts it was a succeess. His debilitating seizures were eradicated. Yet, there were
unanticipated side effects.
W.J. emerged from the surgery with his language and reasoning abilities
intact. But post-operative testing by Michael Gazzaniga, then a graduate student under
the neuroscientist Roger Sperry, revealed certain deficits. Prior to the operation,
Gazzaniga flashed images of various objects in either the right or left area of W.J.'s
visual field. Before the operation, W.J. had no difficulty in identifying the objects
regardless of where in his visual field the image was presented. After the operation,
however, when an object was displayed to W.J.'s left visual field, he was unable to say
what he saw. When asked, he reported not seeing anything. It seemed as though W.J. was
blind in his left eye, but things were not so simple.
After W.J. reported not seen anything, Gazzaniga asked him to point out what
he had just seen from a collection of objects. His hand correctly pointed out the
correct object. It seemed that part of W.J.'s brain, a part that could not communicate
verbally, possed the knowledge of what was flashed on the left side. It had seen the
object. These experiments helped prove that visual stimuli received by one's left eye is
processed by the right hemisphere, and visual stimuli from the right eye is processed by
the left hemisphere. At the time it was known that each hemisphere controlls muscles on
the opposite side of the body, but a similar reversal with visual processing was not known.
Later it was found that for most right-handed men the language center of the
brain is found predominently in the left hemisphere. Left-handed men, and women, are
more likely to have language capacities in both hemispheres. This fact, together with
the previous disoveries regarding the reversal of motor control and perception fully
explains W.J.'s side effect. When the image was shown to his left eye only his right
hemisphere saw it. Lacking the ability to verbalize a response, the right hemisphere
remains mute when asked what it just saw. Yet the right hemisphere is able to control
the muscles on the left-side of the body. Therefore his right hemisphere, using his left
hand, could point out what it has just seen. Later experiments by other "split-brain"
cases lend further confirmation to this explanation.
Thirty years after working with W.J., Michael Gazzaniga was still studying
split-brain cases. In one experiment involving a patient named Joe, Gazzaniga flashed
two different images simultaneously. The image of hammer was shown on the right-hand
side of the screen, while the image of a saw was shown on the left. The exchange between
Joe and Gazzaniga went as follows:
Gazzaniga: "What did you see?"
Joe: "I saw a hammer."
Gazzaniga: "Just close your eyes, and draw with your left hand. Just let it go."
With his eyes closed, Joe's left hand draws the image of a saw.
Gazzaniga: "That's nice, what's that?"
Joe looks at his drawing and answers "A saw."
Gazzaniga: "What did you see?"
Joe: "A hammer."
Gazzaniga: "What'd you draw that for?"
Joe: "I don't know."
This experiment makes clear that Joe saw both images, but his experience is
fractured. One half of his brain observed the hammer while the other half observed the
saw. It is as though two independent minds are present in one skull. What was previously
a singular consciousness is now two. Another split-brain patient, Paul, helped
demonstrate this.
Paul was unusual in that he possessed verbal capacities in both his right
and left hemispheres. This enabled each of his minds to be interviewed concerning their
thoughts, beliefs, and desires. When asked his name, both hemispheres answered "Paul."
When asked his location, both answered "Vermont." But when asked what he wanted to be,
his right hemisphere answered "Automobile racer" while his left answered "Draftsman."
These experiments took place during the Watergate scandal, and so Paul's opinion of
President Nixon was queried. His right hemisphere expressed "dislike" while his left
hemisphere expressed "like." One wonders how Paul would have voted. It might depend on
which hand he used to pull the lever.
In addition to preferences, hemispheres can differ even on fundamental
beliefs. The neuroscientist Vilayanur Ramachandran recounted the case of a patient with
a right hemisphere that believed in God and a left hemisphere that did not. Sometimes
these conflicts manifest physically. In a condition known as /alien hand syndrome/,
split-brain patients may find one hemisphere, and the limbs it controls, behaving
independently from and contrary to the will of the other. One patient struggled to get
dressed in the morning. While his left hemisphere (and right hand) tried to pull his
pants up, his left hand would pull them down. On a separate occasion, this same patient
became angry at his wife. His left hand attacked her while his right hand tried to
protect her!
Roger Sperry, who received a Nobel prize for his work on split-brains,
remarked "Although some authorities have been reluctant to credit the disconnected minor
hemisphere even with being conscious, it is our own interpretation, based on a large
number and variety of non-verbal tests, that the minor hemisphere is indeed a conscious
system in its own right, perceiving, thinking, remembering, reasoning, willing, and
emoting, all at a characteristically human level, and that both the left and the right
hemisphere may be conscious simultaneously in different, even in mutually conflicting,
mental experiences that run along in parallel."
On Tue, Feb 3, 2015 at 12:01 AM, meekerdb <meeke...@verizon.net
<mailto:meeke...@verizon.net>> wrote:
I think "conscious" is ambiguous. From what I've read the two halves of
the split
brain are not both conscious in the sense of having an internal narrative;
only one
half is verbal. Both halves are conscious in the sense of processing
information
and influencing action - as my dog is conscious and Bruno's jumping spider
are
conscious.
Brent
On 2/2/2015 9:41 PM, Jason Resch wrote:
What are your thoughts on split brains which develop two independently
conscious
minds?
We're they always two minds, or do they become such when they can't
communicate?
Jason
On Monday, February 2, 2015, meekerdb <meeke...@verizon.net
<mailto:meeke...@verizon.net>> wrote:
> On 2/2/2015 8:37 PM, Jason Resch wrote:
>
> You can no more assume those other parts of your brain are unconscious
than you
can assume other beings lack consciousness. You might even have solved it
consciously but are amnesiac about it.
>
> Poincare's unconscious was pretty smart, it could prove theorems his
consciousness couldn't. So JKC would say that proves his unconscious was
conscious. I think that's what Bruno calls []f.
>
> I infer (not assume) other beings are conscious because they are very
similar to
me and act like I act when I'm conscious. Pieces of brain don't look much
like me
and they don't act like me.
>
> Brent
--
You received this message because you are subscribed to the Google Groups
"Everything List" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to everything-list+unsubscr...@googlegroups.com.
To post to this group, send email to everything-list@googlegroups.com.
Visit this group at http://groups.google.com/group/everything-list.
For more options, visit https://groups.google.com/d/optout.
