30/03/2009 by admin.

Alva Noe has recently published, Out of Our Heads: Why You Are Not Your Brain, and Other Lessons From the Biology of Consciousness. “The central idea of (this book) is that consciousness is not something that happens inside us — not in our brains, or anywhere else; it is something we do.” It is not his central idea I want to discuss but what he is asking science to do.

In an interview with Gordy Slack (here), Noe said:

A:….Francis Crick did us a major service by taking seriously and publicizing the problem of consciousness. But in the journal Nature he wrote, “Scientists need no longer stand by listening to the tedious arguments of philosophers perpetually disagreeing with each other. The problem of consciousness is now a scientific problem.”

I say, “Bravo!” Consciousness is a scientific problem! But Crick framed the problem in terms of an unquestioned set of philosophical dogmas; namely that the key to consciousness will be found in the brain, that that’s literally where experience and thought take place. My book is not anti-science; it’s a challenge to science to get serious. It’s deluded to think we’re free of philosophy.

Q: Is your battle a turf war between philosophy and neuroscience?

A: Not at all. I think these are scientific questions. I want to help science take them over. But I think science is in philosophically troubled waters here and it’s just not ready yet to go it alone.

Q: You’re arguing that all we’ll learn about by studying the brain is the brain. We’ll never learn from the brain what love is? Or what religion is? Or consciousness?

A: Right. And that the radically reductionist view is not only unfounded, but it’s also ugly. And dangerous.

Q: Dangerous, how?

There are practical dangers, like raising expectations too high for specific scientific programs. The motivation for proceeding along some line, or justification for funding it, may be based on the assumption that it will find the place where consciousness is happening.

Second, the question of consciousness is a problem for all of us — not just for science. We all want to know how to understand humans and think about ourselves. And claiming that neuroscience is going to explain us to ourselves is false advertising. It’s important that we not believe it.

But the view that the self and consciousness can be explained in terms of the brain, that the real us is found inside our skulls, isn’t just misleading and wrong, it’s ugly. In that view, each of us is trapped in the caverns of his own skull and the world is just a sort of shared figment. Everything is made interior, private, rational and computational. That may not pose a practical danger, but it presents a kind of spiritual danger.

In that view, each of us is an island of intellect, alone. When you think of us as just interior neurological mechanisms, you see us as alienated from the world around us. The world shows up for us as bits of information that we decipher, like linguistic relics of an ancient culture that we have to interpret. Like when Mr. Spock says, “What is this strange kissing custom?” The danger is alienation, plain and simple. We’re strangers in a strange land.

I find this a very sad and ugly picture of our circumstance. Now contrast that view with a sense of ourselves as engaged in the flow, responsive to the things going on around us, part of the world. It’s a very different picture.”

I must admit that I find it very difficult, even impossible, to understand what he is proposing for the meaning of brain, consciousness, or self. It looks like, but may not be, just an engaging word game. But I do think I understand what he is saying about science and I disagree.

1) Science does not choose what it studies. It studies what scientists have the tools to study, and find interesting/important questions and have support/funds to study. All three must exist in most cases. As the public and most scientists find the question of consciousness interesting and important, what is done in this field comes down to tools. Neuroscientist look at what they have the tools to look at. The tools to date are very rough and limited. The study of the brain and consciousness is just at its beginning.

2) Science is always as reductionist as it has to be and as holistic as it can be. Scientists are not afraid of reduction or of holism. By and large, a complex system has to be understood by understanding the parts and then the sub-assemblies and then the whole. Of course there are levels of hierarchy. The heart can be studied on the level of an organ without a great deal of knowledge about muscle proteins or the quarks they are composed of. Still at every level there is usually a reductionist to holistic progression.

3) Ugliness has nothing to do with understanding. The point of science is understanding not beauty. By the time a theory becomes an accepted consensus, it takes on beauty. Personally, the satisfaction of understanding makes the theory beautiful not the other way around.

4) Philosophy has a great deal to offer in areas where science does not yet have the tools to delve. And it has a great deal to offer an established theory in clarifying what it means in a large context. But in the stage of investigation that has not come near strong theories yet (let alone accepted ones), philosophy is not particularly helpful and can hinder clarity.

5) The idea that understanding our consciousness as a function of our brains is going to alienate us from the world seems completely unfounded.

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27/03/2009 by admin.

A paper published a year and a half ago is similar to the Gaillard paper that has been discussed in the last two posts. The older paper is titled Brain Dynamics Underlying the Nonlinear Threshold for Access to Consciousness and its lead author is Antoine Del Cul  (here). The methods used have less resolution in some ways then the Gaillard group but have the advantage of varying the masking in small steps between unconscious and conscious events. In the transition region between ‘seen’ and ‘not seen’ it is very informative.

Using scalp electrode they recorded ERPs (event related potentials) during testing. A target was shown briefly (16ms) and was followed by a mask. The time between the target and the mask was varied and this SOA (stimulus onset asynchrony) crossed a threshold from subliminal to conscious perception. The transition was documented in two ways: a forced choice and a subjective report.

The effect that occurred with the same threshold curve as consciousness was called the P3 wave. It was not a local potential but spread across both hemispheres and from the front to the back of the cortex. It occurred about 400 ms after the target. Up until the P3 wave there were only smaller differences between the data for subliminal and conscious processing and these differences did not show a threshold effect but varied in a linear way.

This gives some information to settle a question in my mind. Which of the following is closer to what happens?

1.      Subliminal and conscious perception are entirely different processes – ruled out.

2.      Subliminal and conscious perception start out the same but then differ progressively – seems indicated.

3.      Subliminal and conscious perception are the same process and consciousness occurs (or not) after perception is complete – not ruled out or indicated.

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24/03/2009 by admin.

There is a good description of the global workspace model of consciousness quoted below. It comes from the paper mentioned in the last post, Gaillard’s Converging Intracranial Makers of Conscious Access (here).

“This model, in part inspired from Bernard Baars’ theory, proposes that at any given time, many modular cerebral networks are active in parallel and process information in an unconscious manner. Incoming visual information becomes conscious, however, if and only if the three following conditions are met: Condition 1: information must be explicitly represented by the neuronal firing of perceptual networks located in (sensory) areas coding for the specific features of the conscious percept. Condition 2: this neuronal representation must reach a minimal threshold of duration and intensity necessary for access to a second stage of processing, associated with a distributed cortical network involved in particular parietal and prefrontal cortices. Condition 3: through joint bottom-up propagation and top-down attentional amplification, the ensuing brain-scale neural assembly must “ignite” into a self-sustained reverberant state of coherent activity that involves many neurons distributed throughout the brain.

Why would this ignited state correspond to a conscious state? The key idea behind the workspace model is that because of its massive interconnectivity, the active coherent assembly of workspace neurons can distribute its contents to a great variety of other brain processors, thus making this information globally available. The global workspace model postulates that this global availability of information is what we subjectively experience as a conscious state. Neurophysiological, anatomical, and brain-imaging data strongly argue for a major role of prefrontal cortex, anterior cingulate, and the associative areas that connect to them, in creating the postulated brain-scale workspace.”

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21/03/2009 by admin.

A very important investigation has been reported. The original paper is here; it is reviewed in ScienceDaily here, The New Scientist  here, and Neurophilosophy here. The research was done by a French team led by R. Gaillard.

In the course of treating 10 epileptic patients, electrodes were placed in their brains to identify the focuses of their attacks. The patients agreed to take part in some research while the electrodes were in place. The data from electrodes placed inside the brain has resolution (both in timing and location) that neither brain scans nor EEGs have. On the other hand the researchers used only a few electrodes (176) and they are placed where they were needed for clinical reasons not for research reasons. The patients were shown words under conditions where some reached consciousness and some did not. The differences between the electrode signals in these two conditions were collected to give a picture of the difference between processing of sensory input that ends in consciousness and that which doesn’t. This is an attempt at the ‘holy grail’ of the NCC, neural correlates of consciousness.

The results were:

1.      No specific seat of consciousness was found but rather there was an involvement across most the cortex.

2.      The early stages (less the 200ms) of conscious and unconscious processing were very similar.

3.      “Conscious word processing was associated with the following four markers: (1) sustained iERPs within a late time window (>300 ms after stimulus presentation); (2) sustained and late spectral power changes, combining a high-gamma increase, beta suppression, and alpha blockage; (3) sustained and late increases in long-range phase coherence in the beta range; and (4) sustained and late increases in long-range causal relations.” In other words, when the word became conscious (1) activity relating to the word continued past 300 msec (2) the late activity lasted some time and involved an increase in high frequency, decrease in medium frequency and blocking of low frequency waves (3) the medium frequency waves became synchronized between distant parts of the cortex (4) changes in one part of the cortex caused changes in distant parts.

4.      The results were consistent with B. Baar’s Global Workspace model of conscious access. I believe it might be consistent with a number of other models as well.

5.      Activity started in the back of the brain, moved progressively forward and reached the frontal cortex in those events reaching consciousness. It then feed back to re-activate the areas in the back of the brain again.

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18/03/2009 by admin.

Let us do a little thought experiment.

I am walking down a street that I do not know and a come to a T where I must go either left or right. I look both ways and see no particular difference in the streets: the same types of buildings, same width of street, same density of traffic and pedestrians. Which way to go?

I decide that this is a good time to examine free will. I will decide which way to go with just an act of will without deliberation – there being nothing I can see to deliberate about. I go left.

A little way down the leftward street, there is a fault in the sidewalk pavement and I trip, fall and hurt myself. What immediately goes through my mind? Why did I turn left? I am no longer interested in the freedom of my decision. I want to know the reasons for choosing left over right so that I may be able to avoid dangerous situations in the future. I now will regret my game of mentally flipping a coin if I can see any way I might have foreseen an advantage to right or a disadvantage to left.

When a decision becomes important rather than trivial, then we suddenly are more interested in finding the appropriate answer rather than the free one. Then cause and effect becomes very important.

When I made that choice to go left, I could also have thought to myself (once the decision was made) that it was not a choice at all but predestined. I was bound to make that decision. But when I fall, I forget my ruminations on my lack of choice. I want knowledge of why I make that decision so that I can do better at the next T in my life.

Neither the idea of predestination or of free will is very useful to us. What we want is to understand, nurture and use our decision making processes so that we make good choices. We actually don’t care whether our actions are pre-determined because we cannot use that idea to bypass actually making the decision to act in some way. We actually have to make the decision in order to know what choice it was that was unavoidable.

We want our decisions to be in our short and long term self-interest plus legal and moral. Where those criteria conflict, we want to best compromise in keeping with our situation and our values. When it matters, we judge ourselves on the quality of our decisions – they give us pride and self-satisfaction or guilt and shame. Even if there is complete pre-destination and no free will, we feel responsibility for our actions and this feeling is not illogical.

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15/03/2009 by admin.

An item in Science Daily, Echoes Discovered in Early Visual Brain Areas Play Role in Working Memory, talks about how we keep things in mind when they are no longer in sight (here).  

Vanderbilt University researchers have discovered that early visual areas, long believed to play no role in higher cognitive functions such as memory, retain information previously hidden from brain studies… The results were published Feb. 18 online by Nature.

“We discovered that early visual areas play an important role in visual working memory,” Frank Tong… said. “How do people maintain an active representation of what they have just seen moments ago? This has long been a conundrum in the literature.

“Before, we knew that early visual areas of the cerebral cortex that are the first to receive visual information were exquisitely tuned to process incoming visual signals from the eye, but not to store this information,” Tong said. “We also knew that the higher-order brain areas responsible for memory lack the visual sensitivity of early brain areas, but somehow people are able to remember a visual pattern with remarkable precision for many seconds, actually, for as long as they keep thinking about that pattern. Our question was, where is this precise information being stored in the brain?

“Using a new technique to analyze fMRI data, we’ve found that the fine-scale activity patterns in early visual areas reveal a trace or something like an echo of the stimulus that the person is actively retaining, even though the overall activity in these areas is really weak after the stimulus is removed,” Tong continued.

“Visual cortex has always been thought to be more stimulus driven and has not been implicated in cognitive processes such as memory or active maintenance of information,” Stephenie Harrison, lead author of the research … said. “By using a neural decoding technique, we were able to read out what people were holding in their visual memory. We believe this sustained visual information could be useful when people must perform complex visual tasks in everyday life.”

Research subjects were shown two examples of simple striped patterns at different orientations. They were then told to hold either one or the other of the orientations in their mind while being scanned using fMRI. … By analyzing responses over several trials, we were able to accurately read out which of the two orientation patterns a subject was holding in his or her mind over 80 percent of the time.”

The researchers found that these predictions held true even when the overall level of activity in these visual areas was very weak, no different than looking at a blank screen. This suggests that the act of remembering an image leaves some sort of faint echo or trace in these brain areas. These activity traces are weak but are quite detailed and rich in information.

“By doing these pattern analyses, we were able to find information that was hidden before. We do not know for sure, but it’s possible that a lot of information in the brain might be hidden in such activity patterns,” Tong said. “Using this decoding technique and others, neuroscientists might get a better understanding of how the brain represents specific cognitive states involving memory, reminiscing, or other visual experiences that do not obviously lead to a huge amount of activity in the visual areas.”

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12/03/2009 by admin.

In the New Scientist there is an article, How to spot a hidden religious agenda, which is about spotting what appear to be scientific articles but are not. (here) Among other ideas, Gefter warns against the “invocation of Cartesian dualism- where the brain and mind are viewed as two distinct entities, one material and the other immaterial.”

Also Mind Hacks has pointed to a letter in Science (here)

“Today’s issue of Science has a letter from neuroscientist Martha Farah and theologian Nancey Murphy warning against ‘non-materialist neuroscience’ becoming the new front-line in the religion wars.

Most religions endorse the idea of a soul (or spirit) that is distinct from the physical body. Yet as neuroscience advances, it increasingly seems that all aspects of a person can be explained by the functioning of a material system. … models of perceptual and motor capacities such as color vision and gait do not directly threaten the idea of the soul. You can still believe in what Gilbert Ryle called “the ghost in the machine” and simply conclude that color vision and gait are features of the machine rather than the ghost.

However, as neuroscience begins to reveal the mechanisms underlying personality, love, morality, and spirituality, the idea of a ghost in the machine becomes strained. Brain imaging … pharmacologic influences … the effects of localized stimulation or damage, demonstrate that the brain processes in question are not mere correlates but are the physical bases of these central aspects of our personhood. If these aspects of the person are all features of the machine, why have a ghost at all?

By raising questions like this, it seems likely that neuroscience will pose a far more fundamental challenge than evolutionary biology to many religions. Predictably, then, some theologians and even neuroscientists are resisting the implications of modern cognitive and affective neuroscience. “Nonmaterialist neuroscience” has joined “intelligent design” as an alternative interpretation of scientific data. This work is counterproductive, however, in that it ignores what most scholars of the Hebrew and Christian scriptures now understand about biblical views of human nature. These views were physicalist, and body-soul dualism entered Christian thought around a century after Jesus’ day.

As I’ve noted before, I remain sceptical that this will pose much of a threat, largely due to the fact that non-materialist neuroscience is not particularly new - many famous neuroscientists (including the Nobel prize-winning John Eccles) have been explicitly non-materialist with few contemporary ripples.

Unlike evolution, which bluntly contradicts what many religious texts claim, very few holy books describe any concepts of the soul that can be directly contradicted by neuroscience.

However, there is certainly some interest in the neuroscience bashing among Christian fundamentalists, who recently held their first conference on the issue. We shall have to see how successfully they manage to enthuse their flock.”

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09/03/2009 by admin.

A fairly old (1997) paper by Suddendorf and Fletcher-Flinn, Theory of Mind and the Origins of Divergent Thinking (here) has an interesting study showing that TOM is related to creativity. Here is the abstract:

The development of a `theory of mind’ may not only be important for understanding the minds of others but also for using one’s own mind. To investigate this supposition, forty children between the ages of three and four were given false-belief and creativity tasks. The numbers of appropriate and of original responses in the creativity test were found to correlate positively with performance on false-belief tasks. This association was robust, as it continued to be strong and significant even when age and verbal intelligence were partialled out. The results support the hypothesis that the meta-representational skills involved in theory of mind also affect the way children can access and scan their own mental repertoire beyond the areas of currently activated content (i.e. divergent thinking). With the advent of theory of mind a basic cognitive shift takes place in human development, and possibly took place in cognitive evolution.

They point out that TOM is important for social understanding and also for understanding and utilizing one’s own mind. The key seems to be the capacity to represent in the mind various presentations.

Because the creativity tasks did not involve any obvious kind of mental attribution, 

this finding points to another factor underlying both measures. The prime candidates, 

since the relationship holds even when intelligence and age are partialled out, is 

improved metarepresentational capacity and the ability to disengage from the 

immediate present. Understanding false beliefs in others requires the individual to 

dissociate from the immediate situation and to form a representation of the other’s 

representation. Similarly, one may argue that the creativity task requires the 

children to dissociate from the immediate situation and to represent one’s own 

knowledge, scanning it for items with a particular feature. This theoretical argument

 is consistent with the informal observation that during the testing procedure 

younger children tended to look for answers in their immediate environment, while 

older children gazed at the ceiling, apparently looking “inside” for appropriate 

responses. The data support the hypothesis that a general, rather than a 

specifically social, representational improvement takes place between age 3 and 4.   

The ability to juggle two variations of our model of the world at the same time seems to be important 

to our social life and our general intelligence/creativity. I think it would be important to metaphorical 

or analog thinking too. So when I understand electrical current by reference the flow of a liquid, 

for example, I have to hold the wire and the river in my mind at the same time and compare them. 

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06/03/2009 by admin.

A week or so back there was an item in ScienceDaily, How we think before we speak: making sense of sentences. (here) I was reminded of it when I encountered an ‘up the garden path’ remark.

Linguists have a method of diagramming a sentence to make its grammar clear. If the sentence can be successfully diagrammed then it is grammatical and each word is given its function in the sentence. Diagramming works well with written language. But with spoken language or very difficult written language, it is possible to be misled at the beginning of a sentence so that the sentence is parsed in a way that makes no sense by the end of the sentence. It has to be re-parsed to make it understandable. This is a sentence that leads one ‘up the garden path’. With my bias to consider spoken language as real language and written language as somewhat artificial, I think of garden path sentences as ungrammatical even if, when the whole sentence is available, it can be diagrammed successfully. Wikipedia supplied these examples:

“The old man the boat.”

(The elderly are the crew of the boat)

“The man whistling tunes pianos.”

(The man who is whistling also tunes pianos)

“The cotton clothing is made of grows in Mississippi.”

(The cotton that clothing is made of is grown in Mississippi)

Back to the article – it shows how the listener predicts what the speaker is going to say next.

In … Current Directions in Psychological Science Jos J.A. Van Berkum …describes recent experiments using brain waves to understand how we are able to make sense of sentences. (They) examined Event Related Potentials (or ERPs) as people read or heard critical sentences as part of a longer text, or placed in some other type of context. ERPs are changes in brain activity that occur when we hear a certain stimulus, such as a tone or a word. Due to their speed, ERPs are useful for detecting the incredibly fast processes involved in understanding language…listeners only need a fraction of a second to determine that a word is out of place, given what the wider story is about. As soon as listeners hear an unexpected word, their brain generates a specific ERP, the N400 effect (so named because it is a negative deflection peaking around 400 milliseconds). And even more interesting, this ERP will usually occur before the word is even finished being spoken…Van Berkum speculates that “the linguistic brain seems much more ‘messy’ and opportunistic than originally believed, taking any partial cue that seems to bear on interpretation into account as soon as it can.”

But how does the language brain act so fast? Recent findings suggest that, as we read or have a conversation, our brains are continuously trying to predict upcoming information. Van Berkum suggests that this anticipation is a combination of a detailed analysis about what has been said before with taking ‘quick-and-dirty’ shortcuts to figure out what, most likely, the next bit of information will be.

One important element in keeping up with a conversation is knowing what or whom speakers are actually referring to. For example, when we hear the statement, “David praised Linda because. . .,” we expect to find out more about Linda, not David. Van Berkum and colleagues showed that when listeners heard “David praised Linda because he. . .,” there was a very strong ERP effect occurring with the word “he,” of the type that is also elicited by grammatical errors. Although the pronoun is grammatically correct in this statement, the ERP occurred because the brain was just not expecting it. This suggests that the brain will sometimes ignore the rules of grammar when trying to comprehend sentences.

These findings reveal that, as we make sense of an unfolding sentence, our brains very rapidly draw upon a wide range of information, including what was stated previously and who the speaker is, in helping us understand what is being said to us. Sentence understanding is not just about diligently combining stored word meanings. The brain rapidly throws in everything it knows, and it is always looking ahead.

This implies that we experience a prediction from just past information into the near future – so that our ‘present’ is approximately what should be happening ‘now’. This feed forward has been shown in vision by the nature of illusions and is now shown in hearing. It also appears to be true for motor movement.

Posted in timing | 2 Comments »

03/03/2009 by admin.

Here is one way to look at perception.

Think of a glass. I reach for it in order to pick it up and fill it with wine. But instead of a smooth lift, my hand raises it a little too fast and it feels a little warmer than expected. In a flash the glass-glass becomes a plastic-glass and I have a feeling that it is not the right glass for my wine. This change in my perception of the world happens in a split second.

In effect the constraints on my perception of the world have changed and therefore the best fit with the constraints changes. I go from having a glass-glass in my hand to having a plastic-glass. My vision gives a large number of constraints on my world, so does hearing, so do all the senses of touch, etc. My memory of what the world was previously and what I expect it to be now are also large sets of constraints. I was born with a framework world and have added constraints through learning throughout my life. What I perceive must be consistent with all these constraints at the same time.

Many times a second, a new best fit model of the world is put in memory.

If we think of the brain as an analog computer, or a massively parallel computer or an enormous network of processors, it is not difficult to see how this model of the world can be formed so quickly. The signals rattle around for a short time and then stabilize, the model is stored and the process repeats.

The question now is – is consciousness the newly minted memory or the process of making the memory, the stabilized model or some aspect of using the model, or some combination?

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