Paul P. Mealing

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Saturday, 3 April 2010

Consciousness explained (well, almost, sort of)

As anyone knows, who has followed this blog for any length of time, I’ve touched on this subject a number of times. It deals with so many issues, including the possibilities inherent in AI and the subject of free will (the latter being one of my earliest posts).

Just to clarify one point: I haven’t read Daniel C. Dennett’s book of the same name. Paul Davies once gave him the very generous accolade by referencing it as 1 of the 4 most influential books he’s read (in company with Douglas Hofstadter’s Godel, Escher, Bach). He said: “[It] may not live up to its claim… it definitely set the agenda for how we should think about thinking.” Then, in parenthesis, he quipped: “Some people say Dennett explained consciousness away.”

In an interview in Philosophy Now (early last year) Dennett echoed David Chalmers’ famous quote that “a thermostat thinks: it thinks it’s too hot, or it thinks it’s too cold, or it thinks the temperature is just right.” And I don’t think Dennett was talking metaphorically. This, by itself, doesn’t imbue a thermostat with consciousness, if one argues that most of our ‘thinking’ happens subconsciously.

I recently had a discussion with Larry Niven on his blog, on this very topic, where we to-and-fro’d over the merits of John Searle’s book, Mind. Needless to say, Larry and I have different, though mutually respectful, views on this subject.

In reference to Mind, Searle addresses that very quote by Chalmers by saying: “Consciousness is not spread out like jam on a piece of bread…” However, if one believes that consciousness is an ‘emergent’ property, it may very well be ‘spread out like jam on a piece of bread’, and evidence suggests, in fact, that this may well be the case.

This brings me to the reason for writing this post:New Scientist, 20 March 2010, pp.39-41; an article entitled Brain Chat by Anil Ananthaswarmy (consulting editor). The article refers to a theory proposed originally by Bernard Baars of The Neuroscience Institute in San Diego, California. In essence, Baars differentiated between ‘local’ brain activity and ‘global’ brain activity, since dubbed the ‘global workspace’ theory of consciousness.

According to the article, this has now been demonstrated by experiment, the details of which, I won’t go into. Essentially, it has been demonstrated that when a person thinks of something subconsciously, it is local in the brain, but when it becomes conscious it becomes more global: ‘…signals are broadcast to an assembly of neurons distributed across many different regions of the brain.’

One of the benefits, of this mechanism, is that if effectively filters out anything that’s irrelevant. What becomes conscious is what the brain considers important. What criterion the brain uses to determine this is not discussed. So this is not the explanation that people really want – it’s merely postulating a neuronal mechanism that correlates with consciousness as we experience it. Another benefit of this theory is that it explains why we can’t consider 2 conflicting images at once. Everyone has seen the duck/rabbit combination and there are numerous other examples. Try listening to a Bach contrapuntal fugue so that you listen to both melodies at once – you can’t. The brain mechanism (as proposed above) says that only one of these can go global, not both. It doesn’t explain, of course, how we manage to consciously ‘switch’ from one to the other.

However, both the experimental evidence and the theory, are consistent with something that we’ve known for a long time: a lot of our thinking happens subconsciously. Everyone has come across a puzzle that they can’t solve, then they walk away from it, or sleep on it overnight, and the next time they look at it, the solution just jumps out at them. Professor Robert Winston, demonstrated this once on TV, with himself as the guinea pig. He was trying to solve a visual puzzle (find an animal in a camouflaged background) and when he had that ‘Ah-ha’ experience, it showed up as a spike on his brain waves. Possibly the very signal of it going global, although I’m only speculating based on my new-found knowledge.

Mathematicians have this experience a lot, but so do artists. No artist knows where their art comes from. Writing a story, for me, is a lot like trying to solve a puzzle. Quite often, I have no better idea what’s going to happen than the reader does. As Woody Allen once said, it’s like you get to read it first. (Actually, he said it’s like you hear the joke first.) But his point is that all artists feel the creative act is like receiving something rather than creating it. So we all know that something is happening in the subconscious – a lot of our thinking happens where we’re unaware of it.

As I alluded to in my introduction, there are 2 issues that are closely related to consciousness, which are AI and free will. I’ve said enough about AI in previous posts, so I won’t digress, except to restate my position that I think AI will never exhibit consciousness. I also concede that one day someone may prove me wrong. It’s one aspect of consciousness that I believe will be resolved one day, one way or the other.

One rarely sees a discussion on consciousness that includes free will (Searle’s aforementioned book, Mind, is an exception, and he devotes an entire chapter to it). Science seems to have an aversion to free will (refer my post, Sep.07) which is perfectly understandable. Behaviours can only be explained by genes or environment or the interaction of the two – free will is a loose cannon and explains nothing. So for many scientists, and philosophers, free will is seen as a nice-to-have illusion.

Conciousness evolved, but if most of our thinking is subconscious, it begs the question: why? As I expounded on Larry’s blog, I believe that one day we will have AI that will ‘learn’; what Penrose calls ‘bottom-up’ AI. Some people might argue that we require consciousness for learning but insects demonstrate learning capabilities, albeit rudimentary compared to what we achieve. Insects may have consciousness, by the way, but learning can be achieved by reinforcement and punishment – we’ve seen it demonstrated in animals at all levels – they don’t have to be conscious of what they’re doing in order to learn.

So the only evolutionary reason I can see for consciousness is free will, and I’m not confining this to the human species. If, as science likes to claim, we don’t need, or indeed don’t have, free will, then arguably, we don’t need consciousness either.

To demonstrate what I mean, I will relate 2 stories of people reacting in an aggressive manner in a hostile situation, even though they were unconscious.

One case, was in the last 10 years, in Sydney, Australia (from memory) when a female security guard was knocked unconscious and her bag (of money) was taken from her. In front of witnesses, she got up, walked over to the guy (who was now in his car), pulled out her gun and shot him dead. She had no recollection of doing it. Now, you may say that’s a good defence, but I know of at least one other similar incident.

My father was a boxer, and when he first told me this story, I didn’t believe him, until I heard of other cases. He was knocked out, and when he came to, he was standing and the other guy was on the deck. He had to ask his second what happened. He gave up boxing after that, by the way.

The point is that both of those cases illustrate that humans can perform complicated acts of self-defence without being consciously cognisant of it. The question is: why is this the exception and not the norm?

Addendum: Nicholas Humphrey, whom I have possibly incorrectly criticised in the past, has an interesting evolutionary explanation: consciousness allows us to read other’s minds. Previously, I thought he authored an article in SEED magazine (2008) that argued that consciousness is an illusion, but I can only conclude that it must be someone else. Humphrey discovered ‘blindsight’ in a monkey (called Helen) with a surgically-removed visual cortex, which is an example of a subconscious phenomenon (sight) with no conscious correlation. (This specific phenomenon has since been found in humans as well, with damaged visual cortex.)

Addendum 2: I have since written a post called Consciousness unexplained in Dec. 2011 for those interested.


Anonymous said...

Hi, I am from Melbourne.

None of this explains Consciousness.
By contrast please check out these references on Consciousness


Paul P. Mealing said...

Hi Anonymous,

I'm from Melbourne too (you probably know that already).

"None of this explains Consciousness."

The title is deliberately tongue-in-cheek, hence the caveat in paranthesis.

I'm actually one of those who believes that consciousness will never be explained.

The explanation given in New Scientist may well be the closest we will ever get.

You may be interested in this post on subjectivity that I wrote last June.

Thanks for your comment and your interest.

Regards, Paul.

larryniven said...

I wonder if this same thing is true of people who don't have the neural net that connects the right hemisphere to the left. Presumably not, since the signals would have no way of getting from one side to the other, but on the other hand maybe - at the very least it'd be interesting to check.

Has anything like this been observed in other animals? You'd think that there would be similarities because of our shared evolutionary history, but the kind and extent of those similarities would be relevant to e.g. animal rights discussions and so on.

Paul P. Mealing said...

Hi Larry,

Well you know that left and right hemispheres specialise in humans - for example, it's only the right hemisphere that can recognise faces (refer Oliver Sacks's The Man Who Mistook his Wife for a Hat).

We are not the only species with split brains - dolphins can only have one hemisphere sleep at a time.

People who have had their corpus callusum severed feel like they have 2 brains, from what I've read.

Curiously, today I heard an interview with Norman Doidge MD, Research psychiatrist at the Columbia University Psychoanalytic Centre and the University of Toronto, on brain plasticity.

Last week's issue of New Scientist (the issue after the one I linked to) has a feature on the brain. I might write another post that combines the two (the interview and the new New Scientist article). Because they say conflicting things: our free will is subconscious and we can consciously alter our brains.

If you visit their site, watch the video (for April 2010). It's 8 minutes long, but the last couple of minutes is the most interesting, because it's on robotics.

Regards, Paul.