|Jan30-05, 01:51 PM||#52|
Chapter 1: A Place for Consciousness
Just a question relevant to this discussion. Does Rosenberg discuss blindsight at all? This seems an example of perception that the perceivers are not conscious of. I know that this is a much discussed phenomenon in consciousness research.
|Jan30-05, 08:08 PM||#53|
inputs while lacking the feeling of having seen them - might
be something which only occurs in cases of brain damage, but
seems much more likely to be a significant phenomenon of
intact brain function as well. Indeed, it seems likely that
blindsight (and similar phenomena in other spheres) is an
important ingredient of of a variety of activities where one
wants to move quickly and appropriately, without
"thinking about it".
SH: I haven't come across it yet, but some of my reading is skimming.
This example may be interesting too:
"When we propose that a state of phenomenal consciousness is a
state of sensing something that looks red, which of these senses
[epistemic (knowing) or non-epistemic] of "looks" is meant? The
first possibility is that we are using "looks" in its epistemic
sense. Consider, for example, Wilfrid Sellars' account of what
it means to say "that looks red". Sellars argued that "looks
red" is logically more complicated than "is red"; he says
"being red is logically prior, is a logically simpler notion,
than looking red" (Sellars 1963, 142). To illustrate the
point Sellars tells a story about a necktie shop, whose owner
John has never used electric lighting, and has never reported
the colour of anything except under "standard conditions" of
northern daylight. John has no locutions for reporting
appearances or how colours look; he just reports what the
colour is. Then at last one day John installs electric lighting
and turns it on for the first time. Under the new lights a blue
necktie (as we would say) looks green. His friend Jim
demonstrates how the apparent colour of the necktie changes
depending on the illumination. Initially John is befuddled,
since he doesn't want to say that the blue necktie is green
when inside the shop, or that the lighting changes its colour.
But Sellars tutors him, when inside the lit shop, to stifle
his otherwise natural report that the necktie is green. He is
taught to say first "It is as though I were seeing the necktie
to be green" (Sellars 1963, 143). Finally he acquires a new
locution: the necktie looks green."
SH: There is an experiment which apparently confirms Sellers position.
For Short Presentation Times, Two Stimuli Blend into One
"In one of Efron's experiments, a small red disk, shown for 10 msec on a
monitor, was immediately followed by a green disk at the same location,
also for 10 msec. Instead of seeing a red light turn into a green one, subjects
saw a single yellow flash. Similarly, if a 20 msec blue light was followed by a
20 msec yellow light, a white flash was perceived, but never a sequence of
two lights whose color changed."
SH: To me, this substantiates the view that there can be a difference
between seeing a color as it is and seeing what the color appears to be,
even though we may see the same shade of the color.
"Sellars notes that the experiences that would lead one to
report "it looks green" or "it is green" might as experiences
be indistinguishable from one another. "Two experiences may
be identical as experiences, and yet one be properly referred
to as a seeing that something is green, and the other merely
as a case of something's looking green" (Sellars 1963, 145).
The only difference is epistemic: in one the content of the
experience is endorsed, and in the other it is not.
"It looks green" might also be phrased "Visually it is just
as if I were seeing something green, but I do not endorse the
claim that it is green". I am visually representing something
to be green, but I do not endorse that representation.
The interesting implication is that reports in the epistemic
sense of "that looks green" are themselves reports of a higher
order thought. Unlike reports of the form "that is green", a
report "that looks green" expresses a thought about one's own
mental state. Suppose it means "I am in the sensory state that
would normally lead me to judge that thing to be green, but
something is amiss, and I wish to withhold judgement". It
follows that to be in a state in which something looks green
to me, I must be in a state whose content is "I am in a sensory
state that would normally lead me to judge that thing to be
green, but something is amiss, and I wish to withhold
judgement." This content includes a higher-order comment about
one's own visual state: that it is of a kind that would
normally lead me to judge the thing in question to be green.
Or: that I am in the same kind of visual state that I would
be in if the thing causing it were green."
SH: This "higher-order comment" would appear to dispute Ned Block's
claim that qualia included thought. I notice that Rosenberg distances
[edit: I mean this sounds more like a-consciousness than p-consciousness.]
himself from Block's position in chapter 3. I am not so sure this impacts
Gregg's argument; more like 'what is it like to see red' is not well-defined.
|Feb1-05, 03:06 PM||#54|
APFC.pdf Rosenberg, page 77
"While Liberal Naturalism might feel liberating, we have too much
freedom. To find a place for consciousness, we need tests for the
minimal adequacy of proposed explanations, and also a class of
problems able to provide clues that help us triangulate to the
point of fundamental incompleteness in our knowledge. As a
beginning for the effort, I wish to step back to examine
assumptions and to try to identify the deepest problems and clues
in the vicinity. ...
For example, the links between conscious experience, voluntary
action and functional awareness lead to very interesting puzzles
when considering multiple personality cases (Braude1991), or
commissurotomy patients (Marks 1981) or blindsight patients
(Weiskrantz, 1986; 1988). These puzzle cases can be very seductive,
philosophically, but if Liberal Naturalism is correct they are
likely more intriguing than they are fundamental. Were we to focus
exclusively on overtly cognitive features of consciousness like
these, we would run the danger of confusing the inessential with
the essential, and overlooking promising paths in our search."
GR: "These puzzle cases can be very seductive, philosophically, but if
Liberal Naturalism is correct they are likely more intriguing than they are
SH: I think this should be argued that these cases are intriguing rather
than fundamental, thus Liberal Naturalism is correct.
I find there is disupte about whether there are instances of P-Consciousness
without A-Consciousness or vice versa, but usually both occur. (Ned Block)
Chalmers claims that a clear conceptual distinction can be made
between access and phenomenal consciousness when one considers the
fact that we can imagine P-Consciousness without A-Consciousness
and A-Consciousness without P-Consciousness, and the fact that
A-Consciousness can be accounted for by cognitivist explanations
while P-Consciousness is resistant to such explanations. Unlike
Block, however, Chalmers believes that A-Consciousness and
P-Consciousness *always* occur together.
Or Block again:
"Although phenomenal-consciousness and access-consciousness differ
conceptually (as do the concepts of water and H_2O), we donít know
yet whether or not they really come to the same thing in the brain."
"Blindsight is a well documented phenomenon that occurs in people
who have suffered damage to certain areas of their visual cortex.
These people have a blind region in their visual field, and though
they are aware of their blind spot, they cannot see anything that
is presented to them in that area of space. The important feature
of blindsight is that although subjects are unaware of stimuli in
their blind spots, they have an uncanny ability to `guess' as to
the location, motion and direction of such stimuli. In these cases
their appears to be some visual awareness without the phenomenal
properties that normally occur with visual awareness. For Block,
cases of blindsight point to instances of absent P-consciousness.
Block cannot say, however, that these people have A-consciousness
of the stimuli in their blind region, because the content of the
blind region is not available for the rational control of action.
Blindsight patients must be prompted by an experimenter before
they will `take a guess'. It is unlikely that a hungry blindsight
patient would spontaneously reach for a chocolate in his blind
region. But, says Block, imagine a super-blindsighter who had
acquired the ability to guess when to guess about the content of
her blind field. Even though she doesn't see the objects in her
blind field, she can spontaneously offer verbal reports about
those objects. Information about her blind field just spring into
her thoughts. A super-blindsighter would be A-conscious but not
P-conscious. Whether there are any super-blindsighters is an
empirical question that has not been answered yet, but this does
not affect Block's point. It is enough for Block that they are
conceptually possible. To emphasize this conceptual possibility,
Block points to evidence that the human visual system is divided
into two separate subsystems - the ventral and dorsal subsystems.
In blindsight there seems to be damage to the ventral system,
which Block claims is closely connected to P-Consciousness.
The ventral system is responsible for object recognition and
classification, while the dorsal system is involved in computing
spatial features such as location and motion. Block believes that
because the visual system is comprised of these two visual
subsystems, it would also be conceptually possible to find cases
of P-Consciousness without A-Consciousness. This might occur if
someone incurred damage to their dorsal system, while their
ventral system remained intact. Of course, if Block's distinction
is accurate, we would probably not know if someone was P-Conscious
of events in their visual field without being A-Conscious of those
events because a lack of A-Consciousness implies that content is
not poised for the control of behavior. This includes behavior
such as making the statement: "I see a red object."
|Apr23-06, 01:13 AM||#55|
I just started reading into this discussion, and have read these first 4 pages regarding the first chapter. I've no own background on this subject, just a very w(a/o)ndering mind.
If this drifts too far from the book discussion, do say so.
1. Regarding blind sight:
I believe Pinker defines two aspects of mind, namely sensation and perception. Is there any difference between p-consciousness and sensation, or a-consciousness and perception?
In any case, I think the plausible explanation of blind sight is that to make a conscious effort, your p-consciousness needs to be triggered, however, it's your a-consciousness that performs the mental functions. Therefore, if your p-consciousness is triggered by alternative means (ie. the experimenter giving a verbal cue), you can still perform the mental function.
2. I fail to see why distinguishing between representational consciousness and non-representational consciousness is a good idea. I'm reading Gombrich's Art and Illusion, and it illustrates that our way of representing experiences is something that we learn, something that is a gradual process. I think it's very misleading to describe this representation as if it's an independent, or an at least in some way isolatable aspect of our consciousness. That is, I don't see how this is a process which needs any kind of special institution. I think it's far more likely that representation is just a different way of catagorising experiental data. But of course, these objections might be solved further on. My apologies if this is the case, I've some serious catching up to do.
|May1-06, 01:46 AM||#56|
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