Print

Musings

Posted in Blog

Was that really your decision? - Libet's Half Second

Benjamin Libet made a name for himself by poking into other people's heads. Really. He had a friend neuro-surgeon who would remove parts of people's brains to try to cure them from seizures. The operations were done with the subjects fully conscious. Libet was trying to find something in brains that could explain consciousness and free will.

So, while the patient was lying there, fully conscious, with his skull wide open, Libet would ask them to have a particular thought and then measure the brain activity in specific areas. Or he would stimulate the brain electrically and ask what the patient perceived. Was this ethically kosher? I don't know, apparently the patients gave their consent, but at any rate it was an experimenters' dream come true.

What Libet found was unsettling, to say the least. He found that the neural activity to execute an action started a full half second before the person 'took the decision'. In other words, at a certain instant you decide to lift your finger, but the neuronal commands to the muscles that must do the lifting started already half a second before you decided. So who DID decide, then??

Who is this 'ME' anyway?

We all have a pretty good idea who 'we' are, don't we? But how realistic is that? For starters, read this. Then we can talk...

I read my first book by Douglas Hofstadter more than 10 years ago: Gödel, Escher, Bach. A book exploring individuality (Who is this 'me') as well as (self) consciousness and above all Creativity (which is of course what each of the named persons have in common). Not an easy casual read, but very challenging and thought-provoking. As a follow-up I could suggest a collection of short essays Hofstadter compiled with Daniel Dennett, The Mind's I (a title that can be interpreted in more than one way.

Hearing is not the same as listening

Did you hear what I heard? You'll never know. Our experience of the music we listen to is shaped by extensive processing of the raw vibrations that enter our ears. That processing, by the auditive and cognitive centers of our brain, is itself strongly shaped by a long trail of experiences, expectations and culture. Plus another dozen or more factors.

Most people are not so much interested in the mechanisms (both physically and mentally) behind listening. But listening is really where it all comes together. The enjoyment of music, the interpretation of performances, the judgment of audio reproduction quality is not done with our ears. It is done within our brain. The ears are the sensors that provide our brains with just a physical sample of the air vibrations that represent the sound. What those vibration mean, what they signify, and their ‘quality’ is determined by the brain.

In his excellent book "I am a strange loop", Douglas Hofstadter says it as follows:

"The passage leading from vast numbers of received signals to a handful of triggered symbols is a kind of funneling process in which initial input signals are manipulated or "massaged", the results of which selectively trigger further (i.e., more "internal") signals, and so forth. This baton-passing by squads of signals traces out an ever-narrowing pathway in the brain, which winds up triggering a small set of symbols whose identities are of course a subtle function of the original input signals.[...] In the interest of clarity, I have painted too simple a picture of the process of perception, for in reality, there is a great deal of two-way flow. Signals don't propagate solely from the outside inwards, towards symbols; expectations from past experiences simultaneously give rise to signals propagating outwards from certain symbols. There takes place a kind of negotiation between inward-bound and outward-bound signals, and the result is the locking-in of a pathway connecting raw input to symbolic interpretation."

The brain does NOT take the ears at face value

And in case you are wondering, the brain does NOT take the ears’ input at face value. It is as if the brain says: OK, ears, I get that, but let me look at a couple of other inputs as well. What mood am I in really? How does that equipment actually look? Color, size, cost? Did I build it, or did I lay out hard-earned money to buy it? Or is it from a manufacturer I heard bad things about? Etcetera, etcetera.

How DO you become aware of what you hear? I mean, it's not as if you 'feel' those vibrating hairs in your inner ear and think, aha, that's a piano! No, somehow, the brain makes you 'aware' that you hear a piano. Pretty mysterious, that whole process. But scientific research has come a long way to unravel at least some of it...

A landscape of sound.

Imagine that the brain has many areas that react to a certain input. There is an area that mainly acts on sound, one that mainly acts on colors, one that mainly acts on how you feel (what Antonio Damasio calls 'the body state')

The important word here is 'mainly'. Because, there is extensive interconnection between those area's, there is an exchange of information to built your perception. Call it a landscape of neuronal activity, all over your brain, that couples and integrates all those inputs (external and the internal body state) and which leads to a particular state of 'perceiving' the world around you, sound, sights, emotional state, etc. A nice example, related to the total integration of sensory inputs to the perception of audio, is described by Floyd O'Toole, VP of Acoustical Engineering at Harman, in an article called Audio science in the service of Art. The article is quite long to download, but this excerpt makes this particular point.

So, we are unknowingly building, revising, redoing that perception landscape while we go about our business. But the actual vibrations of those hairs in your inner ears are only ONE input of many others. That particular vibration information gets integrated in the total picture. But unavoidably, in that process, much of it is thrown away. The brain uses this, discards that.

Now, if you are trying to listen attentively to a particular sound, the 'gain' of the sound area is turned up and that of the other areas is turned down. You can be so immersed in listening that you hardly know what's going on around you. You can tune the attention of your brain. In fact, that gain can be turned up so high that you think your hear a sound that isn't there. You can create a certain landscape in your brain that is totally imaginary.

Just making it up

Lets taken an example from vision because vision experiences are much easier to discuss. Focus your attention on your mother's face. Got that? OK. Now, I assume your mother is not right there with you (if so, try your father's face). Do you realize what is going on? You 'see' something that isn't there, that is constructed by your brain from memories. A figment of your imagination if there ever was one. Now, very likely you also have a particular emotional feeling, connected to your mother. You may remember a nice meal she cooked, or you remember her serious illness last year, or you feel guilty because you haven't called her lately. All constructs from your brain, created without any physical sensory inputs.

It's even worse. If indeed you remember that nice meal, you probably 'see' how she smiled at that occasion when you complimented her. Or, if you remember the sickness, you probably 'see' her as a sick person. If it was a serious sickness, chances are that you actually 'feel' bad. Not only does the brain create a perception all by itself, it also selectively 'shapes' that creation depending on which memory you happen to access and it influences your 'body state' to match the perception. When you imagine a bad situation, your body also starts to 'feel bad'.

Closing the circle (sort of)

Negotiating the 'I' - I have been reading about these 'consciousness' issues a lot. And there are many books that give the impression that the genesis of a self-awareness can be understood, yet I never did! Until I read "The crucible of consciousness - an integrated theory of mind and brain" by Zoltan Torey. Right there in the first few pages it clicked in my brain.

Most investigators agree that the development of language was crucial to the development of self-awareness. Why is that? Well language provided two capabilities: firstly, it made it possible to refer to one self. "I feel that this is wrong." 'I' and 'wrong' are all symbols; language made it possible to talk in symbols. "Food", "he", danger", all symbols for something. Secondly, while you think about the symbols, and construct language to refer to them or to discuss them, there is a rapidly oscillation-like attention-shift in your higher brain center between the symbols that we perceive, and the verbal constructs that refer to them. We are conscious of this oscillatory attention-shifting, and it is this awareness that makes us aware that there is 'something' inside us that is 'us'.

This processing is not going on on-line, so to say. It's like an independent 'think tank', if you will, which can run on itself, and then we are absorbed in thought, but still using symbols that we also use if we would put our musings on-line and spoke them. It is telling that when you think, you think in 'language', i.e. in symbols that are words or word-percept combinations.

I find this highly interesting and I can start to understand at least how 'self-awareness' could arise. Whether it is correct is to be seen, but a somewhat sensible theory is better than none; at least you have made a start...

Want to build one of my designs?

I am flattered but would also like us to agree on a few rules.

My designs are the best I can make them, including reliability and safety. A lot of effort, time and money goes into them, and I enjoy doing it.

Nevertheless, I have obviously no control over how, where or when somebody would use a design of me. Therefore, I cannot guarantee that it will do as advertised in all cases and circumstances. I also have to decline any and all responsibility for any damages, direct or consequential, resulting from the use of my designs. Sorry about that, but that's how my lawyer wants it...

If you want to build one for your own use, go ahead. It would be nice if you would let me know how it all works out.

If you like to use one of my designs for a commercial product, we can discuss the terms of such use. If you plan to make money out of them, I would like to have some compensation for my work and effort as well. Or, if you are in need of a design consultant for a project, let me know. I’m sure we can work something out to mutual benefit.