The Libet experiments and what they mean for how the brain initiates actions

[Graeme M]

I think this comes under the subject cognitive science but I guess it falls into neuroscience and philosophy as well...

 

As I understand it, the Libet experiments seemed to show that people begin to do things before they have decided to do them.

These experiments and others since have been debated hotly in terms of what they mean for free will. In essence, evidence for the brain initiating a voluntary movement of the hand before the conscious decision to do so rests with neurological tests that show that preparation for the movement ('Readiness Potential') is registered several tenths of a second before the conscious decision is made.

Libet himself claimed that the data indicated that the brain signals the intention to undertake a motor act before any conscious decision to do so, which indicates that a conscious decision to act is in fact a post hoc mental state deriving from the brain's directive state.

From what I've read (which admittedly is not that much), it's not quite clear whether all possible conditions have been properly tested - for example, it seems to me that on being told what to do, the subjects have entered a readiness state. They are expecting to have to move their hand. I would want to see evidence that a completely spontaneous act shows the same outcome. That might be by instructing the subjects in one case, but spring on them a different unexpected case. I'm not sure if this has been tested.

Anyway, here is a good and recent summary of the current state of this debate:

http://www.bethinking.org/human-life/the-libet-experiment-and-its-implications-for-conscious-will

And here is a recent(ish) article that offers a different take on what has happened.

https://www.newscientist.com/article/dn22144-brain-might-not-stand-in-the-way-of-free-will/

Here Aaron Schurger claims that the accumulation of random neural noise looks like a readiness potential as it approaches a threshold. Although the article is a bit brief and it's probably not clear enough to make any reasonable assessment of Schurger's claims, it seems that he is suggesting that the subjects in whom the noise is closest to the threshold will be the quickest to react to the stimulus, while those with little accumulation will be much slower to react.

Presumably this means that those who reacted quickest will combine the neural noise with the actual signals to move and the resulting EEG trace will look like the RP arose before the decision to act (ie, similar to the traces in Libet's experiments).

I sort of follow that, but the obvious question must be that while this would look the case for those with neural noise approaching the threshold, it would not for those whose noise levels are low. That would suggest (for Schurger to propose this hypothesis) that in Libet's experiments there must have been cases where the RP arose before the decision to act, some at the same time, and some even later (in fact on average they should be later unless neural noise in most people is quite close to threshold generally). In other words, Libet's data must have shown a reasonably wide spread of RP onset.

In what I have read of Libet, I got the sense while in some cases there were variations, on average the RP was high prior to decision making. This seems to have been confirmed in later experiments by both Libet and others.

I wonder if anyone knows the current state of the science in terms of the Libet findings? Has it been definitively determined that Schurger's hypothesis explains the strange data, or is it still open to contention? In other words, do we generally accept that motor cortex readiness potential arises before conscious decision making?

[Strange]

As I understand it, the Libet experiments seemed to show that people begin to do things before they have decided to do them.

 

Or, more plausibly, they have made the decision before being aware they have made the decision.

 

And I don't see how this is relevant to free will (although perhaps it depends which of the multitude of meanings is intended). It is still the person making the decision, even if they are not consciously aware of it.

[Graeme M]

Well, I suppose you could interpret it that way. I think the argument at the heart of it is that if the brain simply responds to its environment and directs the body to act and the idea of a conscious decision arises from that process (after the action), then there is no actual choice involved by a 'conscious' subject. In other words, the sense of decision making is illusory. We only ever do what our brain directs us to do, and it only does that in response to environmental stimuli.

[studiot]

Since I had not heard of Libet until you brought it up I know considerably less than you do about it.

 

So I am only commenting on your conclusions in which you seem to be implying, if not explicitly stating, that the brain is incapable of thought or creation that is independent of external stimulus.

 

I am not arguing that external input does not stimulate brain processes, merely observing that some of the output of the brain seems to me to bear no relation to external input.

 

For instance how do you explain the conception of a work of art eg a novel or a symphony?

How about explaining a hallucination?

Edited August 10, 2015 by studiot

[Strange]

Well, I suppose you could interpret it that way. I think the argument at the heart of it is that if the brain simply responds to its environment and directs the body to act and the idea of a conscious decision arises from that process (after the action), then there is no actual choice involved by a 'conscious' subject.

 

What is "choice" other than the brain responding to external stimuli (and using memories, learning and instinct)?

 

You seem to imply that there is something other than the brain that could be making the choice.

[Graeme M]

I don't know that much about Libet's work, I only came across it the other day and wondered what had been learned in recent times about this particular matter. I don't have any particular view about the findings. There are some pretty serious philosophical implications arising from any sense that the brain is not directed by the 'conscious' mind and as I gather from some of the articles I read it's led to considerable debate from those who argue for free will and those who argue against that. Libet is referenced in the book Consciousness Explained by Daniel Dennett - I'm currently reading it and went off to find out more about the reference.

 

My own personal view is that the brain's operations are all there is and "I" am simply the manifestation of a communications process - that is I'd probably think Libet's findings do point to an underlying phenomenon. But I stress that's just my own take on things and not backed by anything more than some thinking and reading. As far as hallucinations and such like, I suspect these arise from improper processing by the communications process. I can imagine a case in which the brain provides some kind of abstracted representation of underlying processing from which to draw in communicating internal states.

 

I'm not sure why symphonies and art etc would point to the brain doing anything more than processing external input combined with internal representations - for example some forms of internal feedback loops might lead to novel neural arrangements.

 

But that's just some casual uninformed thoughts. As I said, I'm really just asking after how current science views Libet's experimental findings.

[studiot]

That's all very well and thank you for the reply, but it didn't address my comment about your conclusion.

 

Namely I was offering situations where the brain produces what seem to me to be spontaneous independent thoughts.

 

Lot's of musicians report that the tune 'just popped into my head' or words to that effect.

 

Another example occurred to me subsequently,

 

The golf swing, whereby golfers rehearse their shot several (many?) times before the actual event.

 

This is an example of the brain attempting control over external conditions, not just response to them.

[Graeme M]

I didn't say I'd reached a conclusion, I was observing what Libet's experiments suggested. In that vein, there is a new idea emerging in the cognitive sciences around the idea of enactivism, which posits that cognition is not just the simple response to external stimuli and thence instruction to the body, but a more interactive two way process in which the motor actions actually contribute to the process of cognition. Without understanding this idea in detail, it seems that the brain both directs the body to interact with its environment as well as responds to that interaction.

 

http://www.acadiau.ca/~dreid/enactivism/EnactivismDef.html

 

Your example of something popping into mind would be a fine example of the brain processing under the surface so to speak and then passing the result to the conscious mind.

[studiot]

 

I think the argument at the heart of it is that if the brain simply responds to its environment and directs the body to act and the idea of a conscious decision arises from that process (after the action), then there is no actual choice involved by a 'conscious' subject. In other words, the sense of decision making is illusory. We only ever do what our brain directs us to do, and it only does that in response to environmental stimuli.

 

I can only take this as your conclusion drawn from from the material you presented.

 

If that is not your conclusion, please say so and tell us what is.

 

However I don't believe the important matter is whose conclusion this is.

What I am saying is that in my opinion there is truth in the mechanism, but it falls a long way short of the whole story and that the brain not only responds, but also initiates, observes, measures, recalibrates, and sometimes modifys.

The fact that I can so readily produce examples supports this.

[Graeme M]

I wouldn't argue, as I said I was merely interested in where Libet's observations have gone. I would say I have no specific conclusion regarding what that data illustrates, what I wrote was my take on what I read.

When I said that the brain responds to external stimuli, I didn't mean in the sense that it is a mechanical automaton that simply 'goes through the motions'. I would imagine that the brain does much of what you describe, however the question is the extent to which 'you' are consciously choosing to direct matters or whether that is an illusion. Libet's data, and some of the interpretations of that, suggest the idea that the brain does do all of these things but that it does that rather independently of what you consciously experience (although that then raises the problem of what I mean by conscious experience).

Given you seem keen to uncover my own private ideas about this, I'll offer some rough thoughts about what I think consciousness is. I stress these are just my own rough thoughts. I still wanna know more about Libet's findings!!

I think the brain uses both external input as well as internal states/representations to direct behaviours. I think the inner voice that most of us think of as "I" is a process that facilitates communication. Communication is an advantageous feature and is an obvious adaptation to improve individual and group fitness. But it can not add anything to the mix. That is, if we look at it evolutionarily, the earliest organisms simply reacted to their environment and evolution has only that to build upon, layers of complexity around responding to the environment. I can't see how it might add some other disembodied entity such as a soul or a mind.

When I look at consciousess, I am not entirely sure what I am looking at, but if I suggest it is, at the most general level, the act of sensing or awareness then it is something I share with other organisms. I think in general this accords with Thomas Nagel's sense of 'what it is to be a bat'.

On the other hand, if I think more specifically of consciousness as the act of speaking about things internally, I consider this in terms of the origins of language processing. Language functions to facilitate communication. A communications process allows me to codify underlying neural states into a shareable form. Clearly it is very useful, and highly advantageous, to be able to share information about an environment.

For humans, this means we can generate a public perception space - knowledge - that is accessible by all members of the group. Groups can use language - our communications processor - to share knowledge, to learn. As a communicating group, we are more fit than we would be without language.

Equally, it seems to me that evolution will make use of functional modules in more than one way, so it would make sense for the communications process to enhance several functional capacities.

I suggest these are

1. Two way communication and hence knowledge sharing.

2. Directives - one person can direct another person. But equally a person can direct himself.

3. Action oriented perception.

4. Development of 'mind'.

I suggest that without language a creature is aware or conscious in the Nagelian sense, however substantially limited in terms of action. Here I mean action to mean something more akin to goal oriented behaviour, whether that be as simple as movements with a purpose or something like planning or conseptualising. The comms process permits us to express information about our underlying neural states in abstract form hence the ability to produce art or music or stories. Each of these are simply acts of communication - public sharing of information as part of that public knowledge space.

So my view is that the brain does the work with the goal of behavioural direction. "I" am a process that reflects those internal states, primarily for the purpose of knowledge building (public sharing). "I" arise after the fact in externally directed behaviour but equally "I" can feed back information to the underlying processes for internally directed behaviour. The critical point though is that none of this is as a result of some separate mindful entity - a homunculus observing affairs in the Cartesian Theatre. "I" am still simply an organism reacting to environmental pressures.

Edited August 10, 2015 by Graeme M

[studiot]

Surely there is more to this.

 

Even at the level of a virus there is an attempt to 'direct and control' its environment, as well as react to it.

 

That is what altering DNA/RNA is all about (I'm not sure of the biochemical details).

 

 

But it can not add anything to the mix.

 

 

I don't see why not.

Edited August 10, 2015 by studiot

[MonDie]

Graeme M, you can give subjects a choice, and the RP tells which choice they're about to make before the time they reportedly made it. I think this "choice" represents the "spontaneous act" you're looking for.

 

Wolpe & Rowe 2014 have a different criticism. The reported time of decision might not be accurate, and they may need to develop more objective measures of the timing of the impulse to move. So... is our sense of free will erroneous, or is it our sense of timing of mental events that's wrong? http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4064703/

 

The rest of this post is personal speculation, and a researcher in the field may be able to refute it. Anway, IMO, it's a problem that the brain wasn't wired for Libet tasks, but for tasks more like the following.

A pellet will be shot at exactly 300 seconds, and I want to block it. However, it takes x milliseconds for the photoreceptor signals to reach my occipital lobe and for my brain to process them, and y milliseconds for the impulse to move to reach my arm. Might some built-in offsets be adaptive? Maybe there's a forward offset for movement impulses, causing me to judge the movement impulses as occurring late, and to thus send these impulses sooner. Thus an internal offset regarding the timing of mental events corrects for the external offset that is due to neural transit times.

Maybe such an internal offset not only exists, but incidentally affects other judgements as well, like judging when a decision was made. They won't know until they have the more objective measures that Wolpe and Rowe speak of.

Edited August 10, 2015 by MonDie

[Graeme M]

MonDie, yes I agree re the timing thing, what I read suggests a pretty uncertain approach to timing. I'll read your link though I suspect it's the work referred to in the original article I posted. That's why I was interested to see if any further investigation has uncovered more to this (as the Aaron Schurger item suggests). I agree too re the speculation - that's just my own ideas there. I don't wish to spend time on those, my interest is purely with the Libet data and what it suggests.

 

It's a very complex thing but I suppose a lot depends on what one defines as consciousness. I think here they are talking about conscious decisions to act (ie a voluntary act). In the case of Libet and your example, the subject is aware of the likely event and of the need to act. However the difference is that in Libet's case the subject chooses when to act. In your pellet case, although the subject knows he has to react, he still has to await an external stimulus before reacting. What happens from there is a reaction time event - detect the movement of the pellet (or the time) and react to it.

 

Studiot, I don't think anyone. least of all Libet, is claiming that there is no action to control and direct. What is suggested by the data (and what I personally think) is that there is no conscious "I" directing things. Here I mean "conscious I" to mean a sort of disembodied entity separate from the brain. As far as I know from my limited reading, neuroscience (and many modern philosophers) agree with that idea. But it's still something of an open question I think as to whether subjects have the freedom to make conscious, or voluntary, choices. An organism might make 'choices' but is that a voluntary act the way that we like to imagine it, or is simply that when a range of possible actions can be taken, the option represented by the highest potential in a neural state is the one that fires the action.

 

One could argue that the highest potential is caused by the "I" weighing up the options, or that it is simply a largely mechanical process which the brain undertakes. It's wired to generate multiple possible scenarios which are in effect just multiple states arising from the processing of internal and external data. It doesn't decide according to some higher directive, it just acts when one state crosses a threshold.

 

Update: MonDie, that article you linked to is from 2014 which is very recent. Thanks for that, I'll definitely read it today.

Edited August 10, 2015 by Graeme M

[Acme]

... I think the inner voice that most of us think of as "I" is a process that facilitates communication. ...

See I Am A Strange Loop

I Am a Strange Loop is a 2007 book by Douglas Hofstadter, examining in depth the concept of a strange loop to explain the sense of "I". The concept of a strange loop was originally developed in his 1979 book Gödel, Escher, Bach.

 

“ In the end, we are self-perceiving, self-inventing, locked-in mirages that are little miracles of self-reference. ”

 

— Douglas Hofstadter, I Am a Strange Loop p.363

...

No need to respond here as no synopsis satisfies the need to read it. Anyway, I'm sure I have introduced Hofstadter's ideas on the concept of strange loops & consciousness a half dozen times or more here in different threads over the years and all to little or no acclaim. If your interested in the "I" then you may find Hofstadter well reasoned, contemporary, and informative.

[studiot]

 

Studiot, I don't think anyone. least of all Libet, is claiming that there is no action to control and direct. What is suggested by the data (and what I personally think) is that there is no conscious "I" directing things.

 

I don't think any evidence to support this has been offered so far.

[Graeme M]

Acme, yes, you have recommended 'Strange Loops' to me before, and I've had a brief look. That book is on my list to read, but I've got a few others to plough through first so I don't have any thoughts on Hofstadter's ideas at this stage. Do you know how his idea is seen by those studying/researching neurobiology and the philosophy of mind?

 

Studiot, I think when I say "suggested by the data", I am not claiming that the data necessarily evidences that conclusion. It's just an interesting piece in a larger puzzle, a piece I am curious to know more about. My personal view is clearly at odds with your own but that's neither here nor there. I also make no claim to having in-depth knowledge on the subject.

[Acme]

Acme, yes, you have recommended 'Strange Loops' to me before, and I've had a brief look. That book is on my list to read, but I've got a few others to plough through first so I don't have any thoughts on Hofstadter's ideas at this stage. Do you know how his idea is seen by those studying/researching neurobiology and the philosophy of mind?

 

...

Acknowledged. No, I do not know about others' views of Hofstadter, but I'll have a look around. As to reading Hofstadter, kudos for expressing the intention to do so. I would of course recommend bumping him to the front, as he does address why the neurobiology -while interesting- is insufficient to the task at hand.

 

P.S. Here is a 2007 review of Hofstadter's strange loops from Scientific American; it touches on the insufficiency I just mentioned.

A New Journey into Hofstadter's Mind:The eternal golden braid emerges as a strange loop

[david345]

Since I had not heard of Libet until you brought it up I know considerably less than you do about it.

 

So I am only commenting on your conclusions in which you seem to be implying, if not explicitly stating, that the brain is incapable of thought or creation that is independent of external stimulus.

 

I am not arguing that external input does not stimulate brain processes, merely observing that some of the output of the brain seems to me to bear no relation to external input.

 

For instance how do you explain the conception of a work of art eg a novel or a symphony?

How about explaining a hallucination?

It took the human species thousands of years before it could write, sing, or draw art work. Humans devoleped these tools very slowly over many years. This isn't stuff which just pops in your head. Consider a child abandoned in the woods at birth. This child would not have access to the outside influences we have. This child wouldn't sing any songs or draw any pictures. If the child was truly a genius it might use a stick as a tool. This stuff just doesn't pop in your head.

[Acme]

Addendum: I had a look at the paper you linked to Graeme, i.e. The Libet Experiment and its Implications for Conscious Will by Peter G.H. Clarke and in light of its date of publication and references I have to conclude Clarke is unaware of Hofstadter's work. Well, either that or he doesn't accept Dougie's analysis. :shrug:

 

I also searched for 'criticism of strange loops' and 'sassing strange loops' and found only positive reviews; YRMV.

It took the human species thousands of years before it could write, sing, or draw art work. Humans devoleped these tools very slowly over many years. This isn't stuff which just pops in your head. Consider a child abandoned in the woods at birth. This child would not have access to the outside influences we have. This child wouldn't sing any songs or draw any pictures. If the child was truly a genius it might use a stick as a tool. This stuff just doesn't pop in your head.

But you couldn't possibly know about how a child abandoned behaves with no contact because if you did the child -and more to the point you- would have contact. Neither were you present to see/hear the first song, art, or any other first human behavior so your proclamations are nothing more than suppositions.

[david345]

Addendum: I had a look at the paper you linked to Graeme, i.e. The Libet Experiment and its Implications for Conscious Will by Peter G.H. Clarke and in light of its date of publication and references I have to conclude Clarke is unaware of Hofstadter's work. Well, either that or he doesn't accept Dougie's analysis. :shrug:I also searched for 'criticism of strange loops' and 'sassing strange loops' and found only positive reviews; YRMV.But you couldn't possibly know about how a child abandoned behaves with no contact because if you did the child -and more to the point you- would have contact. Neither were you present to see/hear the first song, art, or any other first human behavior so your proclamations are nothing more than suppositions.

This is a poor argument. One could watch him with cameras without disturbing him. Historians have a pretty good idea when certain human behaviors developed. Your argument sounds more like a far reaching conspiracy theory.

[Acme]

Addendum: I had a look at the paper you linked to Graeme, i.e. The Libet Experiment and its Implications for Conscious Will by Peter G.H. Clarke and in light of its date of publication and references I have to conclude Clarke is unaware of Hofstadter's work. Well, either that or he doesn't accept Dougie's analysis. :shrug:

...

On that note, I also see this with the paper:

About the Author

Dr. Peter Clarke was an associate professor at

the University of Lausanne, Switzerland, until

2012. He taught anatomy and neuroscience and

did research on the mechanisms of neuronal

death. His main focus is now on the

philosophical implications of neuroscience. He

is an associate editor of Science and Christian

Belief and is a member of The Faraday Institute

Advisory Board. He is the author of Dieu,

l’homme et le cerveau (Croire Pocket, 2012).

Wiki says of the group running the publication:

Christians in Science (CiS) is a British organisation of scientists, philosophers, theologians, ministers, teachers, and science students, predominantly evangelical Christians,[1] concerned with the dialogue between Christianity and science.

I'm good with the neuroscience, but that Christian belief and evangelizing business is a red flag for me. I do hope that's not where all this is headed.

... And here is a recent(ish) article that offers a different take on what has happened.

https://www.newscientist.com/article/dn22144-brain-might-not-stand-in-the-way-of-free-will/

 

Here Aaron Schurger claims that the accumulation of random neural noise looks like a readiness potential as it approaches a threshold. Although the article is a bit brief and it's probably not clear enough to make any reasonable assessment of Schurger's claims, it seems that he is suggesting that the subjects in whom the noise is closest to the threshold will be the quickest to react to the stimulus, while those with little accumulation will be much slower to react. ...

Following a link chain from that article I located the full text of Schurger et al's study. Read it here: An accumulator model for spontaneous neural activity prior to self-initiated movement

Edited August 11, 2015 by Acme

[Graeme M]

Thanks Acme, I am reading through the Wolpe and Rowe paper, very interesting and exactly what I was after. I'll tackle the Schurger study after that. I did note that religious undertone to the Clarke article but I felt it was still a somewhat useful overview even though I felt his conclusions seemed a little strong for the background evidence. Given though the increasingly monistic view of modern theology, I don't think identifying underlying physical causes for conscious experience (or 'agency' as I think it's termed in this field) is a no-go area for people like Clarke, but they are for sure going to react against any suggestion there is no 'free will'. I think Clarke suggests it's OK that immediate reactions are entirely without conscious direction, but that more deliberative decisions (eg moral or ethical choices) still need some kind of voluntary directiveness. I guess that rescues us from the bleak prospect of meaningless materialism.

David345, I posed a question a while back that tackled aspects of the question of how the complexity of mind has developed over time.

 

http://www.scienceforums.net/topic/88968-development-of-mind/

 

That's not quite what you were touching on, but there is relevant discussion I think.

[Graeme M]

I've read those papers Acme, and I like Schurger's argument. Briefly, he argues that random fluctuations in neural activity will tend to approach a threshold over time; once the threshold is exceeded a motor action is decided. This is in respect to voluntary, non temporally constrained decisions to move.

 

In other words, the Libet experiment suggests that for voluntary actions the brain prepares for action BEFORE the conscious decision to act. Hence the urge to act is a post facto addition to experience. Schurger suggests that typical neuronal activity buzzes away and it is not until a threshold point is reached that the decision to act occurs (and the act itself).

 

That is, when we are thinking of doing a voluntary act, the choice of when to act is precipitated by the neural activity exceeding the threshold. The RP curve typical of the Libet experiment simply describes normal activity with the actual motor response grafted on (because a motor response occurred).

 

I think this still suggests that the motor act occurs without conscious direction as such, it serves merely to bring decision point and motor response closer together temporally. But it does show that the decision to act and the act are not separated as such, rather they both arise from the same underlying neural activity.

 

But I also may be misreading the paper. It may be that when the activity reaches close to the threshold it's already primed by an expectation to act at some time, and thus at that point it tips over the edge and causes the conscious decision from which the act arises.

 

Even then though I do not think it rescues us from the sense that the 'voluntary, conscious' act arises unconsciously from a potential.

 

I'd be interested in anyone else's take on this paper and its findings.

[Acme]

I've read those papers Acme, and I like Schurger's argument.

Roger that. I barely skimmed them for the record.

 

Briefly, he argues that random fluctuations in neural activity will tend to approach a threshold over time; once the threshold is exceeded a motor action is decided. This is in respect to voluntary, non temporally constrained decisions to move.

 

In other words, the Libet experiment suggests that for voluntary actions the brain prepares for action BEFORE the conscious decision to act. Hence the urge to act is a post facto addition to experience. Schurger suggests that typical neuronal activity buzzes away and it is not until a threshold point is reached that the decision to act occurs (and the act itself).

 

That is, when we are thinking of doing a voluntary act, the choice of when to act is precipitated by the neural activity exceeding the threshold. The RP curve typical of the Libet experiment simply describes normal activity with the actual motor response grafted on (because a motor response occurred).

Which all suggests to me brain pathways that have been built up over time by experience, i.e. feedback or -if you will- strange loops.

 

I think this still suggests that the motor act occurs without conscious direction as such, it serves merely to bring decision point and motor response closer together temporally. But it does show that the decision to act and the act are not separated as such, rather they both arise from the same underlying neural activity.

I'm no fan of the banal arguments/debates of 'free will', if that is the crux of your statement here. I acts, therefore I is.

[Graeme M]

Gotta get back to those strange loops! You've about convinced me, I'll see if I can chase up a copy over the weekend.

 

As far as the free will thing, I'm not that's directly my interest, though I suppose it hangs off it. No, I'm more curious about the extent to which we are conscious of our thinking and decision making. Or if you like, does the conscious decision as expressed in my mind result in the behaviour.