21 June 2013

Thin slicing the brain.

Creates a whole lot of data!  Nature reports on 'Whole human brain mapped in 3D' by Helen Shen, June 20, 2013.  The atlas was created from 7400 slices of a human brain, each thinner than a human hair, and nicknamed 'BigBrain'.  Here's the quick summary:
The brain is comprised of a heterogeneous network of neurons of different sizes and with shapes that vary from triangular to round, packed more or less tightly in different areas. BigBrain reveals variations in neuronal distribution in the layers of the cerebral cortex and across brain regions — differences that are thought to relate to distinct functional units.
Given that we are still working on a model for a simple worm with 302 neurons, there's obviously a long way to go with the full human brain.  But you gotta start somewhere, and I'm sure that having an accurate map will help (now just drawn from one example, but as they do more they will get an idea of the individual differences that are possible - I'll bet they can be pretty significant).

18 June 2013

What's the program in the Chinese Room?

It's really big and complicated!  That's my main takeaway from the Dennett writing on the Searle thought experiment (in Intuition Pumps and other books).

Here's the description of the scenario from Wikipedia:
It supposes that there is a program that gives a computer the ability to carry on an intelligent conversation in written Chinese. If the program is given to someone who speaks only English to execute the instructions of the program by hand, then in theory, the English speaker would also be able to carry on a conversation in written Chinese. However, the English speaker would not be able to understand the conversation. Similarly, Searle concludes, a computer executing the program would not understand the conversation either.
So - what might this program consist of?  Obviously there is no simple algorithm for taking in a string of Chinese characters one by one, and sending out a meaningful response character by character.  It would need all sorts of features, such as memory of the current conversation (to provide context to any given input), ability to distinguish questions from comments from opinions, and so much more.  Of course any such program could never be carried out in a step by step manual way by a person, unless you are willing to wait days if not months or years for responses!

If we simply assume that such a program exists and works as described, then it does seem to me that the outsider interacting with the room would grant a level of understanding to it.  The Watson program that can play Jeopardy seems to be getting relatively close to this level of sophistication, although it was built for the Answer/Question format only.

10 June 2013

What is a zombie?

Perhaps a whole lot more than you thought...  thinking on Dennett and the zombie concept, mostly drawn from Intuition Pumps (2013).

The philosophical concept of the zombie seems to start from a fairly simple definition: "a hypothetical being that is indistinguishable from a normal human being except in that it lacks conscious experience, qualia, or sentience." (drawn from Wikipedia)

Dennett's important point is that given this definition, it must be true that this zombie has very complex functional abilities - it must have functionality to support all sorts of things that normal humans can do - such as visual-auditory-olfactory-touch-taste sensory input, memory (perhaps slightly faulty), color recognition, facial recognition & linking face to name, ability to know that recognition of friends & family should trigger different behavior than recognition, say, of a politician, and so much more.  While by definition it does not have conscious experience, it's hard to say how one could ever confirm that this was the case.

Dennett then goes on to examine what he calls a subset of zombies, those which have "equipment that permits it to monitor its own activities, both internal and external, so it has internal (nonconscious) higher-order informational states that are about its other internal states." (p. 290). He calls these 'zimboes' but it's unclear to me whether such equipment is actually necessary in all zombies in order to produce the definitional behavior of being indistinguishable.  Dennett claims that only a zimbo can "hold its own in everyday interactions" - and that's my sense as well - to be indistinguishable from a normal human.  So I guess I'm unsure of why Dennett creates this new category of zimbo, if the zimbo has equipment that all zombies must have.

At a later point, Dennett examines a couple cases of non-normal human pathologies around facial recognition. Prosopagnosics are people who do not recognize people's faces, and people with Capgras delusion who can recognize people but believe they are 'imposters' - not truly the person they resemble. Research on brain function seems to indicate that there are at least two mechanisms at work in normal facial recognition - there's unconscious visual processing going on that also ties into emotional recognition, and there's conscious recognition of 'knowing who it is'.  If you can show that the unconscious mechanisms are broken (as apparently in the case of Capgras), leading to an altered conscious experience (sense of an imposter), then it appears the qualia is quite tightly tied to the unconscious mechanisms (but by definition qualia is supposed to be the conscious bit).

In other words, it's hard to draw a neat line around qualia when you look closely.  Again pointing out the difficulty of truly imagining the zombie.

I would argue that regardless of the brain mechanisms in use (and I do agree that many modules or mechanisms are used), the subjective experience as a whole is the emergent phenomenon of interest, and the prosopagnosic indeed has a different subjective experience than normal people, as does the Capgras subject. It is a fact that the Capgras subject is deluded about reality, but that fact doesn't alter the subjective experience of seeing people as impostors.

07 June 2013

Dennett and reports on consciousness...

I've been reading some Daniel Dennett lately (both Consciousness Explained and his new Intuition Pumps) and reflecting on many of his concepts.  Dennett argues for what he calls hetero-phenomenology as a method of scientifically researching consciousness, and this is basically taking reports from subjects in as neutral a way as possible (i.e. minimizing assumptions), and then trying to evaluate and explain these reports (i.e. are they right, what causes them, etc.).  In at least some descriptions, he seems to see the goal as simply a binary true/false evaluation - presumably on whether the perception matches what's really evident (as judged by objective observers).

Rather than a simple binary evaluation of right/wrong, I propose there are multiple angles that can and should be examined.
1. If the report includes descriptions of the world outside the subject, how do these compare to reports of 3rd parties? Or to other measures of reality?
2. If the report includes descriptions of internal sensations, how do these compare to what we know about the physical basis for the senses?
3. If the report includes an explanation or reason for the subject's experience, how does that compare to various existing theories and studies of behavior?

So in the case of the blind spot, I think most people will not report any blind spot, unless they follow a specific procedure, by staring at one point while moving another point that is off to the side closer or farther away until it can't be seen.  Physically we know there are no rods and cones at the back of the eye where the optic nerve exits.  So on criteria 1, there is actually a good match with reality because there appears to bear "filling in" of the spot, likely achieved because the eyes are usually shifting around, not starring at one point, and somehow a full visual field is produced (criteria 2).

Many visual illusions indicate that the perception includes features that are not really in the picture.  This seems to indicate that there is construction or filling in of apparent patterns.  In general I suspect this is a useful feature in dealing with the world, in particular for cases where what we are looking at is partially obscured.  

Now consider a case where the subject unknowingly has been given a drug that commonly causes hallucinations.  The subject reports that the furniture appears to be melting.  Here there is an incorrect match with reality.  If the subject reports that he may be "losing his mind", hopefully the observer will let them know that in fact the experience is due to a drug and will end soon.  The subject did not really know the reason for the experience.
While the subject's report about the outside world is clearly wrong, I don't think we can say that the subject's internal experience is wrong or untrue.  In this case we know the drug has the neurochemical properties which has one effect of altering the subject's experience.

In other cases of anomalous internal experiences, like a near death experience or an out-of-body experience, we can say that other observers in the immediate area could not detect any outside (i.e. real world) trace of it, but not that the report is wrong per se.  I think it's worth trying to both explain how such experiences can occur, and whether such experiences are a result of and/or can result in physical changes (such as neuronal rewiring).