Monthly Archives: April 2010

Libet’s experiment

For the last few days we have been trying to understand the concept of free will from different points
of view and in relation to different fields of science and philosophy. Today we will discuss a very important
and fundamental experiment in neuroscience that may tell us a lot about the relationship between
conscious thought and action- the very question regarding the presence of free will.
 
Benjamin Libet did a series of experiments to determine if there is electrical activity in the brain before
a bodily action. In a set of experiments done in 1980s he was able to show that there was an electrical
signal build-up in the brain about half a second before a physical movement is done. So half a second before
I move my finger, there is an electrical build up in some neurons of the brain. This electrical build up
was given the name “readiness potential” by Libet. That was interesting but that does not tell us about the
relationship between physical movement, “free will” and conscious thought. That was the next experiment that
Libet did in the 1990s.

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In the more advanced experiment Libet put electrodes on the heads of his subjects and asked them to observe
a very fast moving clock. he then asked them to move their wrists whenever they wanted to but note the time
at which the “desire to move the wrist” came into their minds. So there were three time measurements for each
subject:
 
1) The time of the build up of the electrical signals in the brain ( this is the readiness potential)
2) The time when the conscious wish to act occurs in the brain ( this is now called Libet’s W time)
3) The actual time of the physical movement or action.
 
Now we have see that in the experiments conducted in 1980s, Libet had found that the readiness potential happens
upto .5 second or 500 ms before the actual action. Libet found that the conscious will to act occurred about 300 ms after
the readiness potential and about 200 ms before the physical act. So the brain has already initiated an activity
300 ms before you know about it consciously! The conscious desire to move has been caused by electrical signals build up
300 ms prior to it! So the decision to move has been triggered in the brain 300 ms before “you” got to know about it.
This suggests something simple: there seems to be no conscious free will.
 
The experiment was done very carefully and it was adjusted for errors in measurement.
 
It would be interesting to correlate this experiment with the reaction times available in “high speed” ball games like
cricket.
 
regards
Kanwar
 
      
 
========================================================================
Go wondrous creature, mount where science guides
go measure earth, weigh air, state the tides,
instruct the planets in what orbs to run
correct old time, regulate the sun
======================================================================

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Veritas by Kanwarpreet Grewal is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 United States License.

Free Will Theorem

In today’s VERITAS we will study Conway and Kochen’s Free Will Theorem which attempts to connect Quantum Mechanics and the concept of Free will. Before I explain this in detail, let me state the theorem. The Free Will theorem states that if we have free will then the elementary particles also have a degree of free will.

 
Now, let me state another theorem on which the Free Will Theorem is based: The Kochen Specker Theorem. The Kochen Specker Theorem states that the values of quantum mechanical variables is not decided before the experiment is done to measure them. So the theorem states that quantum mechanical variables acquire values only when observed. ( Note: This is not the precise definition. This is a simplistic and inaccurate definition).
 
The Free will theorem is based on three assumptions which have been established by a huge number of experiments:
 
1) Fin: There is a maximum speed for the propagation of signals from one place to another- this follows from the special theory of relativity.
 
2) Spin: If you measure the squared spin of a particle along three orthogonal directions you will always get 2 1s and a 0. So you may get (1,1,0) when you measure the spin along x, y and z direction or get (0, 1, 1) or (1,0 1) etc. But you will always get two 1s and a 0.
 
3) Twin: This assumption states that it is possible to quantum mechanically entangle two particles so that if you measure a certain value of spin in one particle in a direction then you will get the same value of spin when you measure the second particle along the same direction. The two particles can even be light years away and they will still show the same spin value. Such particles are said to be entangled.
 
The Fin assumption is based on Special Relativity. The Spin and Twin assumptions are based on Quantum Mechanics.
 
The Free Will Theorem states that if the experimenter is free to choose which experiment to perform( ie measure spin along which direction), then the results of the experiment is equally free. Now let me state what is meant by free here. By free we mean independent of any previous history. So if an experimenter’s choice is independent of any previous history then the results of the measurement of the particle’s spin is also independent of any previous history.
 
Here is my personal opinion on the theorem: the theorem tries to equate free will with randomness. But can random behavior, even if it is at the most fundamental level, be called free will? Free will has to be a conscious decision and not a random one. If you equate randomness with free will then it is in no way better than determinism as far as fixing moral responsibility is concerned. Does it matter if a murderer says ” I killed because I had no control over my decision- it came from the past states of my neurons”( determinism answer) or says ” I killed because I had no control
over my decision- it came from a random change in my neurons”( free will theorem kind of answer)? The fundamental question still remains: is the person who I call “me” have a “conscious choice” in what to do and what not to do?
 
regards
Kanwar
 
 

 
========================================================================
Go wondrous creature, mount where science guides
go measure earth, weigh air, state the tides,
instruct the planets in what orbs to run
correct old time, regulate the sun
======================================================================
 

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Veritas by Kanwarpreet Grewal is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 United States License.

Free Will and Philosophy

Philosophers have always been interested in the question of free will. There have been philosophers who have
believed in free will and some who have not and some who have believed that both free will and determinism
can exist at the same time. We will understand these different points of view and the arguments for these
diverse points of view in this VERITAS article.
 
The philosophy that believes that determinism exists but free will does not is known as hard determinism.
The philosophy that believes that determinism is false and free will exists is known as metaphysical libertarianism.
 
So hard determinism and metaphysical libertarianism are completely opposite views. Let’s study them in some
more detail:
 
Hard Determinism: Determinism is the idea that the future is caused by the past and present events in accordance
with the laws of nature. This view is best illustrated by a thought experiment called Laplace’s demon. Laplace
was a hard determinist who made a thought experiment: imagine a demon that knows the position and every possible
variable about every atom in the universe. And this demon knows the laws of Physics completely. Then would this demon
not be able to compute the future with certainty? Laplace answers in the affirmative.
                            Now there are different kinds of deterministic philosophies based on the root of the deterministic
laws: The determinism may be based on logic- if x was true earlier so y should be true later. This is called
logical determinism. Or there may be theological determinism: God decides what will happen at all times so there
is determinism caused by the all powerful, all knowing God.
 
Metaphysical Libertarianism: Now lets’ look at the completely opposite view : determinism is false and free will
exists. These theories are also of various kinds. Take for example, the dualistic viewpoint that there is a soul
and there is a body. The body is  ruled by laws of physics externally but the decisions and thought take place
in the soul which is not subject to the laws of Physics. So the dualists are metaphysical libertarinimists who
believe that the soul is the root of free will. This is one viewpoint under Metaphysical Libertarianism. How about
if I were to show that Laws of Physics themselves are not completely deterministic. Then would we not have shown
that there is free will and not even need a soul to justify it. We will study this theory on Monday( day III of the free
will week).
 
Both the above positions, Metaphysical Libertarianism and Hard Determinism, say that if determinism is true
then free will is not and vice versa. So both these above positions consider free will and determinism as
incompatible with each other. Therefore they are both considered as incompatibilism philosophies.
 
There are philosophies that consider free will and determinism as compatible with each other- both can exist
at the same time. These philosophies are known as compatibilism philosophies.         
 
A compatabilist focuses on a slightly different definition of free will. For them free will is defined whether you were
forced by some other person to make a choice or if you did it on your own. So you decide to go and see a movie
and for a compatibilist, that is enough to say that “free will exists” because you did not choose to see the movie
under force from someone else. So a compatibilist will ask you, “could you have chosen differently if you were in a
different mood?”. And if the answer is yes, then he would say that you have a free will. The compatibilist does not
deny that your mood may be from a chain of past events but if they are your own chain of events then your mind
has decided for you and that is free will. This definition of free will is closest to the moral sense that we all have.
We punish people who do something immoral or illegal and we reward the people who are virtuous because most
( if not all) of us believe that the person made the choice himself.
 
So, as you can see, there are a lot of different philosophical opinions on the fundamental question of free will.
On Monday we will talk about the free will theorem. To end the VERITAS I will quote the philosopher, Arthur
Schopenhauer in his essay, “On the freedom of will” :
 
“You can do what you will, but in any given moment of your life you can will only one definite thing and
absolutely nothing other than that one thing”
 
regards
Kanwar
 
                        
 
========================================================================
Go wondrous creature, mount where science guides
go measure earth, weigh air, state the tides,
instruct the planets in what orbs to run
correct old time, regulate the sun
======================================================================

Creative Commons License
Veritas by Kanwarpreet Grewal is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 United States License.

Free Will Week

Friends,

Media_httpmymindonboo_fjsxo

This is the first article in a series of articles that will be posted during the next one week. The theme
topic for the week is Free Will. Here are the topics that will be covered:

1) Thu, 22nd, week kickoff + resending a VERITAS mail on free will that I sent a long time back( 20 Jan, 2004)
2) Friday, 23 April: Review of different philosophical theories and notions on free will
3) Monday, 26th April: Free Will and Physics- the free will theorem
4) Tuesday: 27th April: Free Will and Morals- includes an experiment in psychology
5) Wednesday: 28th April: Free Will and brain signal activation measurement- Libet’s experiment
6) Thursday, 29th April: have not thought about anything yet. Will think about something soon.

So Today I will just resend the VERITAS that I had posted a long time in VERITAS regarding free will
and determinism. This will help you understand the fundamental question before we start going into the
topic deeper from tomorrow.

Your comments and questions are welcome and some of them will be posted each day during the
week.

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Go wondrous creature, mount where science guides
go measure earth, weigh air, state the tides,
instruct the planets in what orbs to run
correct old time, regulate the sun
======================================================================

Mysteries of the Brain – Visual Consciousness

I got several questions and comments on this VERITAS. Posting a few of them:

Apurva Kalia wrote:

“How have these numbers been calculated in some manner?
Is there a way to determine the CPU speed of the visual cortex?
How does one define the no. of bits needed to form conscious awareness?”

My answer:
These are excellent questions and I tried to find the answers. Could manage to find some stuff but not a lot. Scientists took a guinea pig retina and placed it in a dish. They showed it different movies. They connected 7 different types of ganglion cells in the retina to electrodes. The different ganglion cells present different pictures to the brain which then creates the overall pictures. The response time of each cell was measured by the number of electrical spikes per second in the electrodes when seeing the movie.
For more details see:

and

There is an article by Zimmerman called “the nervous system in the context of information theory” in the book “Human physiology” by R. F. Schmidt & G. Thews. We need access to this article to answer Apurva’s questions in detail. I do not have it yet. I will try to get it.

Rakesh Malik wrote:

” FYI — sum total of all the sensory inputs is ~ 11 Mbps. ( this is a number from a journalist and have not been able to corroborate it with published numbers in peer reviewed journals)

Erik Panu wrote:
Hence, why the whole area of metaphysics is popular… and why this movie was interesting to see; see the “Academic Reaction” part of this link in particular:

http://en.wikipedia.org/wiki/What_the_Bleep_Do_We_Know!%3F

Mysteries of the brain – Part 21 : Visual Consciousness

Friends,

Media_httpculturemaki_dhkzs

            This is going to be a very short VERITAS mail. There is something incredibly interesting that I read yesterday and I really wanted to share that with people.

            There is a huge amount of external stimulus that reaches our senses every second. It is estimated that about 10 billion bits(10,000,000,000) of visual information reaches our eyes every second. But the eye has its limits. The optic nerve at the back of the retina can transport only 6 million(6,000,000) bits per second to the brain. The visual cortex in the brain processes only about 10,000 bits per second.
And the no of bits that go to form the conscious awareness of what is being seen is only 100 bits per second.

So though we are able to see 10 billion bits every second through our eyes, our perception of what is being seen is formed by only about 100 bits per second: an insignificant amount of information! So the perception of reality is only triggered by the external stimulus: most of it is formed within the brain. We see a little and we make up a huge amount. This is related to  what Aakanksha told us in :
“VERITAS: Mysteries of the Brain Part 20: Hypnosis”

This applies to all senses. We take very little from the outside word- we make up most of our perceived reality. 
John Milton said ” The mind is its own place, and in itself, can make heaven of Hell, and a hell of Heaven.”

Regards
Kanwar

|======================================================|
Go, wondrous creature! mount where Science guides:
Go, measure earth, weigh air, and state the tides:
Instruct the planets in what orbs to run,
Correct old time and regulate the Sun;
|======================================================|

Creative Commons License
Veritas by Kanwarpreet Grewal is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 United States License.