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© Chris D. Frith, 2007
All Rights Reserved. Authorized translation from the English language edition published by Blackwell Publishing Limited. Responsibility for the accuracy of the translation rests solely with The Dynasty Foundation and is not the responsibility of John Blackwell Publishing Limited. No part of this book may be reproduced in any form without the written permission of the original copyright holder, Blackwell Publishing Limited.
© Dmitry Zimin Dynasty Foundation, Russian edition, 2010
© P. Petrov, translation into Russian, 2010
© Astrel Publishing LLC, 2010
CORPUS® Publishing
All rights reserved. No part electronic version This book may not be reproduced in any form or by any means, including posting on the Internet and corporate networks, for private and public use, without the written permission of the copyright owner.
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Dedicated to Uta
List of abbreviations
ACT - axial computed tomography
MRI - magnetic resonance imaging
PET - positron emission tomography
fMRI - functional magnetic resonance imaging
EEG - electroencephalogram
BOLD (blood oxygenation level dependent)
Foreword
I have an amazing labor-saving device in my head. My brain - better than a dishwasher or a calculator - frees me from the boring, repetitive work of recognizing things around me and even saves me from having to think about how to control the movements of my body. This gives me the opportunity to focus on what really matters to me: friendship and the exchange of ideas. But, of course, my brain not only saves me from a tedious daily work. It is he who forms me who lives in the company of other people. In addition, it is my brain that allows me to share with my friends the fruits of my inner world. So the brain makes us capable of something more than what each of us is capable of individually. This book is about how the brain performs these miracles.
Thanks
My work on the mind and brain was made possible by funding from the Medical Research Council and the Wellcome Trust. The Medical Research Council gave me the opportunity to work in the neurophysiology of schizophrenia through financial support from the Tim Crow Psychiatric Unit at the Northwick Park Hospital Clinical Research Center in London, Harrow, Middlesex. At that time, we could judge the relationship between the psyche and the brain only on the basis of indirect data, but everything changed in the eighties, when tomographs were invented to scan the working brain. The Wellcome Trust enabled Richard Frackowiak to set up the Functional Imaging Laboratory and financially supported my work in this laboratory on the neurophysiological basis of consciousness and social interactions. The study of the mind and brain is at the intersection of many traditional disciplines, from anatomy and computational neuroscience to philosophy and anthropology. I have been very fortunate to have always worked in interdisciplinary – and multinational – research groups.
I have benefited a lot from my colleagues and friends at University College London, especially Ray Dolan, Dick Passingham, Daniel Wolpert, Tim Shallis, John Driver, Paul Burgess and Patrick Haggard. In the early stages of writing this book, I was aided by many fruitful discussions about the brain and psyche with my friends in Aarhus, Jakob Howu and Andreas Röpstorff, and in Salzburg with Josef Perner and Heinz Wimmer. Martin Frith and John Law have, for as long as I can remember, argued with me about everything in question in this book. Eva Johnstone and Sean Spence generously shared with me their professional knowledge about psychiatric phenomena and their implications for brain science.
Perhaps the most important impetus for writing this book came from my weekly conversations with past and present breakfast parties. Sarah-Jane Blakemore, Davina Bristow Thierry Chaminade, Jenny Kull, Andrew Duggins, Chloe Farrer, Helen Gallagher, Tony Jack, James Kilner, Haguan Lau, Emiliano Macaluso, Eleanor Maguire, Pierre Macke, Jen Marchant, Dean Mobbs, Matthias Pessilone, Chiara Portas, Geraint Rees, Johannes Schultz, Suchy Shergill, and Tanya Singer helped shape this book. I am deeply grateful to all of them.
To Karl Friston and Richard Gregory, who have read portions of this book, I am grateful for their invaluable help and valuable advice. I am also grateful to Paul Fletcher for supporting the idea of introducing Professor in English and other characters who argue with the narrator.
Philip Carpenter selflessly contributed to the improvement of this book with his critical remarks.
I am especially grateful to those who read all the chapters and commented in detail on my manuscript. Sean Gallagher and two anonymous readers have made many valuable suggestions for improving the text of this book. Rosalind Ridley made me think carefully about my statements and be careful with terminology. Alex Frith helped me get rid of professional jargon and lack of coherence.
Uta Frith actively participated in this project at all its stages. If she had not set an example and guided me, this book would never have seen the light of day.
Prologue: Real Scientists Don't Study Consciousness
Why psychologists are afraid of parties
Like any other tribe, scientists have their own hierarchy. The place of psychologists in this hierarchy is at the very bottom. I discovered this in my freshman year at university where I was studying science. We were told that college students would, for the first time, have the opportunity to study psychology in the first part of the science course. Encouraged by this news, I went to our group leader to ask him what he knew about this new opportunity. “Yes,” he replied. “But it never crossed my mind that one of my students would be so dumb as to want to study psychology.” He himself was a physicist.
Because, probably, that I was not quite sure what "stupid" meant, this remark did not stop me. I left physics and took up psychology. From then until now, I have continued to study psychology, but I have not forgotten my place in the scientific hierarchy. At parties where scientists gather, from time to time the question inevitably pops up: “What do you do?” - and I tend to think twice before answering, "I'm a psychologist."
Of course, much has changed in psychology in the last 30 years. We borrowed a lot of methods and concepts from other disciplines. We study not only behavior, but also the brain. We use computers to analyze our data and model mental processes. My university badge doesn't say "psychologist" but "cognitive neuroscientist."
Rice. item 1.General form and a slice of the human brain
Human brain, side view (top). The arrow marks the place where the cut shown in Fig. bottom photo. The outer layer of the brain (cortex) is composed of gray matter and forms many folds to fit a large surface area into a small volume. The cortex contains about 10 billion nerve cells.
And they ask me: “What do you do?” It seems to be the new head of the physics department. Unfortunately, my response “I am a cognitive neuroscientist” only delays the denouement. After my attempts to explain what, in fact, my work consists, she says: “Ah, so you are a psychologist!” - with that characteristic facial expression in which I read: “If only you could do real science!”.
A professor of English joins the conversation and raises the topic of psychoanalysis. She has a new student who "doesn't agree with Freud in many ways." In order not to spoil my evening, I refrain from saying that Freud was an inventor, and his reasoning about human psyche have little to do with the case.
A few years ago, the editor of the British Psychiatric Journal ( British Journal of Psychiatry), apparently by mistake, asked me to write a review of a Freudian paper. I was immediately struck by one subtle difference from the articles I usually review. As in any scientific article, there were many references to the literature. Basically, these are links to works on the same topic, published earlier. We refer to them partly in order to pay tribute to the achievements of their predecessors, but mainly in order to support certain statements that are contained in our own work. “You don't have to take my word for it. You can read a detailed rationale for the methods I used in Box and Cox (Box and Cox, 1964).” But the authors of this Freudian article did not at all try to back up the cited facts with references. References to the literature were not about facts, but about ideas. Using references, it was possible to trace the development of these ideas in the writings of various followers of Freud up to the original words of the teacher himself. At the same time, no facts were cited by which it would be possible to judge whether his ideas were fair.
“Freud may have had a great influence on literary criticism,” I tell the professor of English, “but he was not a real scientist. He was not interested in facts. I study psychology by scientific methods.”
“So,” she replies, “you are using a monster of machine intelligence to kill the human in us.”
On both sides of the abyss that separates our views, I hear the same thing: "Science cannot investigate consciousness." Why can't?
Exact and inexact sciences
In the system of scientific hierarchy, "exact" sciences occupy a high position, and "inexact" - low. The subjects studied by the exact sciences are like a cut diamond, which has a strictly defined shape, and all parameters can be measured with high accuracy. "Inexact" sciences study objects that look like an ice cream ball, the shape of which is far from being so definite, and the parameters can change from measurement to measurement. The exact sciences, such as physics and chemistry, study tangible objects that can be measured very accurately. For example, the speed of light (in a vacuum) is exactly 299,792,458 meters per second. A phosphorus atom weighs 31 times more than a hydrogen atom. These are very important numbers. Based on the atomic weight of various elements, one can compose periodic table, which once made it possible to draw the first conclusions about the structure of matter at the subatomic level.
Once biology was not such an exact science as physics and chemistry. This state of affairs changed dramatically after scientists discovered that genes consist of strictly defined sequences of nucleotides in DNA molecules. For example, the sheep prion gene consists of 960 nucleotides and begins like this:
I must admit that in the face of such precision and rigor, psychology looks like a very imprecise science. The most famous number in psychology is 7, the number of things that can be held in working memory at the same time. But even this figure needs to be clarified. An article by George Miller about this discovery, published in 1956, was titled “ magic number seven plus or minus two. Therefore, the best measurement result obtained by psychologists can vary in one direction or another by almost 30%. The number of items we can hold in working memory varies from time to time and from person to person. In a state of fatigue or anxiety, I will remember fewer numbers. I speak English and therefore can remember more numbers than those who speak Welsh. “What did you expect? says the professor of English. “The human soul cannot be straightened out like a butterfly in a shop window. Each of us is unique.”
This remark is not entirely appropriate. Of course, each of us is unique. But we all have general properties psyche. It is these fundamental properties that psychologists are looking for. Chemists had exactly the same problem with the substances they investigated before the discovery. chemical elements in the 18th century. Each substance is unique. Psychology, compared to the "exact" sciences, had little time to find what to measure and figure out how to measure. Psychology as scientific discipline only existed for a little over 100 years. I am sure that in time psychologists will find what to measure and develop devices that will help us make these measurements very accurate.
Exact sciences are objective, inexact sciences are subjective
These optimistic words are based on my belief in the unstoppable progress of science. But, unfortunately, in the case of psychology, there are no solid grounds for such optimism. What we are trying to measure is qualitatively different from what is measured in the exact sciences.
In the exact sciences, the results of measurements are objective. They can be checked. “Don't believe that the speed of light is 299,792,458 meters per second? Here's your equipment. Measure yourself!” When we use this measurement equipment, the results will appear on dials, printouts and computer screens where anyone can read them. And psychologists use themselves or their voluntary assistants as measuring instruments. The results of such measurements are subjective. You can't check them.
Here is a simple psychological experiment. I run a program on my computer that shows a field of black dots continuously moving down from the top of the screen to the bottom. I stare at the screen for a minute or two. Then I press "Escape" and the dots stop moving. Objectively, they no longer move. If I put the tip of a pencil on one of them, I can make sure that this point is definitely not moving. But I still have a very strong subjective feeling that the dots are slowly moving up. If at that moment you were to enter my room, you would see fixed points on the screen. I would tell you that it seems to me that the dots are moving up, but how do you check this? After all, their movement occurs only in my head.
A real scientist wants to independently and independently verify the results of measurements reported by others. “Nullius in verba” is the motto of the Royal Society of London: “Do not believe what others tell you, no matter how high their authority may be.” If I followed this principle, I would have to agree that a scientific investigation of your inner world is impossible for me, because for this I have to rely on what you tell me about your inner experience.
For a while, psychologists pretended to be real scientists by only studying behavior—taking objective measurements of things like movements, button presses, reaction times. But behavioral research is by no means enough. Such studies leave out all the most interesting in our personal experience. We all know that our inner world no less real than our life in the material world. Unrequited love brings no less suffering than a burn from touching a hot stove. The work of consciousness can influence the results of physical actions that can be objectively measured. For example, if you imagine that you are playing the piano, the quality of your performance may improve. So why shouldn't I take your word for it that you imagined playing the piano? Now we psychologists have returned to the study of subjective experience: sensations, memories, intentions. But the problem has not gone away: the mental phenomena that we study have a completely different status than the material phenomena that other scientists study. Only from your words can I learn about what is going on in your mind. You press a button to let me know you've seen a red light. Can you tell me what shade that red was. But there is no way I can get into your mind and check for myself how red was the light that you saw.
For my friend Rosalind, each number has a specific position in space, and each day of the week has its own color (see Fig. CV1 in the color inset). But maybe these are just metaphors? I have never experienced anything like it. Why should I believe her when she says that these are her immediate, uncontrollable sensations? Her sensations relate to the phenomena of the inner world, which I can not verify in any way.
Will big science help inexact science?
Exact science becomes "big science" when it starts using very expensive measuring instruments. The science of the brain went big when CT scanners were developed to scan the brain in the last quarter of the 20th century. One such scanner usually costs more than a million pounds. Through sheer luck, being in right time in the right place, I got the opportunity to use these devices when they first appeared, in the mid-eighties. The first such devices were based on the long-established principle of fluoroscopy. An x-ray machine can show bones inside your body because bones are much harder (dense) than skin and soft tissues. Similar density differences are observed in the brain. The skull surrounding the brain has a very high density, while the density of the tissues of the brain itself is much less. In the depths of the brain are cavities (ventricles) filled with fluid, they have the lowest density. A breakthrough in this field came with the development of axial computed tomography (ACT) technology and the construction of the ACT scanner. This apparatus uses X-rays to measure density and then decides huge number equations (which requires a powerful computer) and builds a three-dimensional image of the brain (or any other part of the body), reflecting differences in density. Such a device for the first time made it possible to see the internal structure of the brain of a living person - a voluntary participant in the experiment.
A few years later, another method was developed, even better than the previous one - magnetic resonance imaging (MRI). MRI does not use X-rays, but radio waves and a very strong magnetic field. Unlike fluoroscopy, this procedure is not at all dangerous to health. An MRI scanner is much more sensitive to density differences than an ACT scanner. On images of the brain of a living person, obtained with its help, different types of tissues are distinguishable. The quality of such images is not lower than the quality of photographs of the brain, after death, removed from the skull, preserved with chemicals and cut into thin layers.
Rice. item 2. An example of an MRI structural image of the brain and a section of the brain removed from a corpse
Above is a photograph of one of the sections of the brain, removed from the skull after death and cut into thin layers. Below is an image of one of the layers of the brain of a living person, obtained by magnetic resonance imaging (MRI).
Structural tomography of the brain has played a huge role in the development of medicine. Brain injuries resulting from traffic accidents, strokes, or tumor growth can have a profound effect on behavior. They can lead to severe memory loss or serious personality changes. Before the advent of CT scanners, the only way to find out exactly where an injury occurred was to remove the skull cap and look. Usually this was done after death, but sometimes in a living patient - when a neurosurgical operation was required. Now tomographs allow you to accurately determine the location of the injury. All that is required of the patient is to lie motionless inside the tomograph for 15 minutes.
Rice. item 3. An example of an MRI scan showing brain damage
This patient suffered two strokes in a row, as a result of which the auditory cortex of the right and left hemispheres was destroyed. The injury is clearly visible on the MRI image.
Structural tomography of the brain is both an exact and a big science. Measurements of the structural parameters of the brain, carried out using these methods, can be very accurate and objective. But what do these measurements have to do with the problem of psychology as an "inexact" science?
Although I must admit that there are some retrogrades who generally deny that the study of the brain or computers can tell us anything about our psyche. - Note. ed.
Believe it or not, this is a reference to a genuine work that substantiates an important statistical method. Bibliographic data of this work can be found in the bibliography at the end of the book. - Note. ed.
She is a specialist in the work of Australian writer Elizabeth Costello. - Note. ed. (Australian writer Elizabeth Costello is a fictional character in the book of the same name by South African writer John Maxwell Coetzee. - Note trans.)
Sheep prion is a protein, the modified configuration of the molecules of which causes the development of a disease in sheep, similar to the disease of a mad cow. - Note. transl.
Working memory is a type of active short term memory. This is the memory that we use when we try to remember a phone number without writing it down. Psychologists and neuroscientists are actively researching working memory, but have yet to agree on exactly what they are researching. - Note. ed.
. “Nullius addictus jurare in verba magistri” - “Without swearing allegiance to the words of any teacher” (Horace, “Messages”). - Note. ed.These were followers of behaviorism, a trend whose most famous representatives were John Watson and Burres Frederick Skinner. The zeal with which they promoted their approach indirectly indicates that all is not well with him. One of the professors I studied with in college was a passionate behaviorist who later became a psychoanalyst. - Note. ed.
Moreover, judging by the results of tomographic studies, the same part of the brain is involved in the reactions of physical pain and suffering of a rejected person. - Note. ed.
. “Big science” is expensive scientific research involving large scientific teams (a colloquial term in modern English). - Note. transl.
€ 4,20 )The famous British neurophysiologist Chris Frith is well known for his ability to talk simply about very difficult problems psychology such as mental activity, social behavior, autism and schizophrenia. It is in this area, along with the study of how we perceive the world, we act, we make choices, we remember and we feel, today there is a scientific revolution associated with the introduction of neuroimaging methods.
Chris Frith. Brain and Soul: How nervous activity shapes our inner world. - M.: Astrel: CORPUS, 2010. - 336 p.
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Prologue: Real Scientists Don't Study Consciousness
Whether we are awake or asleep, the 15 billion nerve cells (neurons) in our brain are constantly sending signals to each other. This consumes a lot of energy. Our brain consumes about 20% of the energy of the entire body, despite the fact that its mass is only about 2% of body weight. The entire brain is permeated with a network of blood vessels, through which energy is transferred in the form of oxygen contained in the blood. The distribution of energy in the brain is very finely tuned, so that more of it flows into those parts of the brain that are most active at the moment. Functional tomographs allow you to record the energy consumption of brain tissues.
This solves the problem of psychology as an "inexact" science. Now we have no need to worry about the inaccuracy, the subjectivity of our information about mental phenomena. Instead, we can make accurate, objective measurements of brain activity. Probably, now I will not be ashamed to admit that I am a psychologist. However, no such device will allow us to see what is happening in the inner world of another person. The objects of the inner world do not really exist.
In this book, I am going to show that there really is no difference between the inner world of man and the material world. The difference between them is an illusion created by our brain. Everything that we know, both about the material world and about the inner world of other people, we know thanks to the brain. But the connection of our brain with the material world of physical bodies is just as indirect as its connection with the non-material world of ideas. Hiding from us all the unconscious conclusions to which it comes, our brain creates in us the illusion of direct contact with the material world. At the same time, it gives us the illusion that our inner world is separate and belongs only to us. These two illusions give us the feeling that in the world we live in, we are acting as independent agents. At the same time, we can share our experience of perceiving the world around us with other people. Over the millennia, this ability to share experiences has created human culture, which in turn can influence how our brains work. By overcoming these illusions created by the brain, we can lay the foundation for a science that will explain to us how the brain shapes our consciousness.
Rice. 1. General view and section of the human brain. Human brain, side view (top). The arrow marks the place where the cut shown in the bottom photo passed. The outer layer of the brain (cortex) is composed of gray matter and forms many folds to fit large area surfaces on a small scale. The cortex contains about 10 billion nerve cells.
PART ONE. What is behind the illusions of our brain
Chapter l. What can a damaged brain tell us?
Everything that happens in the inner world ( mental activity) is caused by, or at least dependent on, brain activity. Brain damage makes it difficult to transmit information about the world that is collected by the senses. The nature of the impact of these damages on our ability to cognize the world around us is determined by the stage of information transfer at which the damage affects.
Observations of people with brain damage suggest that our brain may know something about the world around us that our consciousness does not. Mel Goodale and David Milner studied the woman known by the initials D.F. The experimenter held a stick in his hand and asked D.F. how the stick was positioned. She couldn't tell if the wand was horizontal or vertical or at some angle. It seemed that she did not see the wand at all and was just trying to guess its location. The experimenter then asked her to reach out and take hold of the stick with her hand. It worked out fine for her. At the same time, she turned her hand in advance so that it was more convenient to take the wand. At whatever angle the wand was placed, she could grab it with her hand without any problems. This observation shows that the brain of D.F. “knows” at what angle the wand is located, and can use this information by controlling the movements of her hand. But D.F. cannot use this information to recognize where the wand is located. Her brain knows something about the world around her that her consciousness does not know.
Chapter 2. What a healthy brain tells us about the world
It may seem to us that we directly perceive the world around us, but this is an illusion created by our brain.
Hermann Helmholtz in 1852 put forward the idea that our perception of the world around us is not directly, but depends on "unconscious inferences." In other words, before we perceive any object, the brain must conclude what it might be for the object, based on the information coming from the senses.
Psychologists' favorite tricks are visual illusions (optical illusions). They demonstrate that we do not always see what is actually there (Fig. 2).
Rice. 2. Illusion of Goering. Even if we know that the two horizontal lines are actually straight, they appear to us to be arcuately curved. Ewald Göring, 1861
Examples of such a distorted perception can be found not only in the pages of psychology textbooks. They are also found in the objects of the material world. The most famous example is the Parthenon in Athens. The beauty of this building lies in the ideal proportions and symmetry of the straight and parallel lines of its outlines. But in reality, these lines are neither straight nor parallel. The architects introduced bends and distortions into the proportions of the Parthenon, calculated so that the building looked straight and strictly symmetrical (Fig. 3).
Rice. 3. The perfection of the appearance of the Parthenon is the result of an optical illusion. Schemes based on the findings of John Pennethorne (1844); deviations are greatly exaggerated.
In the 1950s, Eugene Aserinsky and Nathaniel Kleitman discovered special phase sleep during which rapid eye movement occurs. During this phase, our brain activity on the EEG looks exactly the same as during wakefulness. But at the same time, all our muscles are, in fact, paralyzed, and we cannot move. The only exception is the muscles of the eyes. During this phase of sleep, the eyes move rapidly from side to side, despite the fact that the eyelids remain closed (Fig. 4).
Rice. 4. Phases of sleep. (i) wakefulness: fast, asynchronous neural activity; muscle activity; eye movement; (ii) non-REM sleep: slow, synchronous neural activity; some muscle activity; no eye movement; few dreams; (iii) REM sleep: fast, non-synchronous neural activity; paralysis, no muscle activity; rapid eye movement many dreams
- What our brain tells us about our body
In 1983, Benjamin Libet conducted an experiment. All that was required of the subjects was to raise one finger whenever they "would like to do it." In the meantime, the electrical activity of the brain was measured using an EEG machine. The main discovery was that the change in brain activity occurred about 500 milliseconds before a person lifted a finger, and the desire to lift a finger occurs about 200 milliseconds before a person lifts a finger. Thus, brain activity indicated that the subject was about to raise his finger 300 milliseconds before the subject reported that he was going to raise his finger.
This result generated such interest outside the psychological community because it seemed to show that even our simplest conscious actions are actually predetermined. We think we are making a choice, when in fact our brain has already made that choice. But this does not mean that this choice was not made freely. It simply means that we are not aware that we are making a choice at this earlier point in time (Sam Harris in his book concluded differently, believing that the experiment showed the absence of free will).
Rice. 5. Mental events that determine our movements do not occur simultaneously with physical events. The brain activity associated with a particular movement begins before we are aware of our intention to make this movement, but the movement "starts" after we realize that we are starting it.
As we will see after reading the sixth chapter, our perception of the time of performing certain actions is not strictly tied to what is happening in the material world.
Imagine that you are sitting in the dark. I'm showing you a glimpse of a black spot within the frame. Immediately after that, I again briefly show you a black spot within the frame. The spot does not change its position, but the frame is shifted to the right (Fig. 6). If I ask you to describe what you see, you will say: "The spot has moved to the left." This is a typical visual illusion due to the fact that the visual areas of the brain mistakenly decided that the frame remained in place, which means that the spot should have moved. But if I ask you to touch the place where the spot was at the beginning, then you will touch the correct place on the screen - no movement of the frame will prevent you from correctly indicating this place. Your hand "knows" that the stain hasn't moved, even though you think it has.
Rice. 6. Illusion Roelofs. If the frame is shifted to the right, the observer appears to have moved the black spot to the left, despite the fact that it remained in place. But if the observer stretches out his hand to touch the position of the spot imprinted in memory, he does not make such a mistake.
These observations demonstrate that our body can perfectly interact with the outside world even when we ourselves do not know what it is doing, and even when our ideas about the world around us are not true. It may be that our brain is directly connected to our body, but the information supplied by the brain about the state of our body seems to be of the same indirect nature as the information supplied to us about the world around us.
Until the 1980s, neurophysiologists were taught that after we reach the age of about sixteen, the brain matures and growth ceases completely. If the fibers connecting some neurons are destroyed, these neurons will forever remain disconnected. If you lose a neuron, it will never recover. Now we know that this is not the case. Our brains are very plastic, especially when we are young, and remain so throughout our lives. Connections between neurons are constantly being made and broken in response to changes in the environment.
PART TWO. How does our brain do it?
Chapter 4
This is how Bayes' theorem is stated:
Take some phenomenon (A) that we want to know about, and an observation (X) that gives us some information about A. Bayes' theorem tells us how much our knowledge of A will increase in light of new information X. This equation gives us exactly that mathematical formula the belief we were looking for. Belief in this case corresponds to the mathematical concept of probability. Probability measures how much I believe in something.
Bayes' theorem shows exactly how much my belief about A will change in the light of new information X. In the equation above, p(A) is my initial or a priori belief about A before the new information X, p(X|A) is the probability of obtaining information X in case A actually takes place, and p(A|X) is my subsequent, or a posteriori, belief about A given the new information X.
The ideal Bayesian observer. The importance of Bayes' theorem is that it enables us to measure very accurately the extent to which new information should change our understanding of the world. Bayes' theorem gives us a criterion for judging whether we are adequately using new knowledge. This is the basis of the concept of the ideal Bayesian observer - an imaginary being who always uses the information received in the best possible way.
But there is another aspect of Bayes' theorem that is even more important for understanding how our brains work. There are two key elements in Bayes' formula: p(A|X) and p(X|A). The p(A|X) value tells us how much we should change our understanding of the world (A) after receiving new information (X). p(X|A) tells us what information (X) we should expect based on our belief (A). We can look at these elements as tools that allow our brains to make predictions and track errors in them. Guided by our ideas about the world around us, our brain can predict the nature of events that our eyes, ears and other senses will follow: p(X|A). What happens when such a prediction turns out to be wrong? Tracking errors in such predictions is especially important because our brains can use them to refine and improve our understanding of the world around us: p(A|X). After making such a refinement, the brain gets a new idea of the world and can repeat the same procedure again, making a new prediction about the nature of the events tracked by the senses. With each repetition of this cycle, the error in the predictions decreases. When the error is small enough, our brain “knows” what is going on around us. And all this happens so fast that we are not even aware of the entire complex procedure. It may seem to us that ideas about what is happening around us come easily, but they require the brain to relentlessly repeat these cycles of predictions and clarifications.
Our perceptions depend on a priori beliefs. It is not a linear process, like the ones that produce images in a photograph or on a TV screen. For our brain, perception is a cycle. If our perception were linear, energy in the form of light or sound waves would reach the senses, these messages from the outside world would be translated into the language of nerve signals, and the brain would interpret them as objects occupying a certain position in space. It was this approach that made perceptual modeling on first-generation computers such a challenge.
A predictive brain does almost the exact opposite. Our perception actually starts from within - with an a priori belief, which is a model of the world where objects occupy a certain position in space. Using this model, our brain can predict what signals should go to our eyes and ears. These predictions are compared with real signals, and in doing so, of course, errors are found. But our brain only welcomes them. These mistakes teach him perception. The presence of such errors tells him that his model of the world around him is not good enough. The nature of the errors tells him how to make a model that will be better than the previous one. As a result, the cycle repeats again and again, until the errors become negligible. This usually takes only a few such cycles, for which the brain may need only 100 milliseconds.
Where does our brain get the a priori knowledge necessary for perception? Some of this is innate knowledge, stored in our brains over millions of years of evolution. For example, for many millions of years there was only one main source of light on our planet - the Sun. And sunlight always falls from above. This means that concave objects will be darker at the top and lighter at the bottom, while convex objects will be lighter at the top and darker at the bottom. This simple rule is hard-coded into our brains. With its help, the brain decides whether an object is convex or concave (Fig. 8).
Rice. 8. Illusion with dominoes. Above - a half of a domino with five concave spots and one convex one. Below - a half with two concave and four convex spots. You are actually looking at a flat sheet of paper. The spots look concave or convex due to the nature of their shading. We expect the light to come from above, so a convex spot should have its bottom edge shaded, while a concave spot should have its top edge shaded. If you flip the pattern upside down, the concave spots become convex and the convex ones become concave:
Modern technologies allow us to create many new images, which our brain is not able to correctly interpret. We inevitably perceive such images incorrectly.
What we perceive is not those raw and ambiguous signals coming from the outside world to our eyes, ears and fingers. Our perception is much richer - it combines all these raw signals with the treasures of our experience. Our perception is a prediction of what should be in the world around us. And this prediction is constantly tested by actions.
But any system, when it fails, makes certain characteristic mistakes. What mistakes will a system that works by predictions make? She will have problems in any situation that allows for an ambiguous interpretation. Such problems are usually solved by making one of the possible interpretations much more likely than the other. Many of the visual illusions that psychologists love so much work precisely because they trick our brains in this way (see for an excellent illustration).
The very odd shape of the Ames room is designed to evoke the same visual sensations, as an ordinary rectangular room (Fig. 9). Both models, the oddly shaped room and the regular rectangular room, are equally good at predicting what our eyes see. But in experience we have dealt with rectangular rooms so much more often that we inevitably see the Ames room as rectangular, and it seems to us that people who move from corner to corner in it increase and decrease in an unthinkable way. The a priori probability (expectation) that we are looking at a room of such a strange shape is so small that our Bayesian brain does not take into account unusual information about the possibility of such a room.
Our brain builds models of the world around us and constantly changes these models based on the signals that reach our senses. Therefore, in fact, we do not perceive the world itself, but its models created by our brain. We can say that our sensations are fantasies that coincide with reality. Moreover, in the absence of signals from the senses, our brain finds how to fill in the gaps that arise in the incoming information. There is a blind spot in the retina of our eyes where there are no photoreceptors. It is located where all the nerve fibers that carry signals from the retina to the brain come together to form the optic nerve. There is no place for photoreceptors there. We don't realize that we have this blind spot because our brain always finds something to fill this part of the visual field with. Our brain uses signals from the area of the retina immediately surrounding the blind spot to make up for this lack of information.
Chapter 6
The ability to see the movement of living objects is deeply rooted in our brain. As early as six months of age, infants prefer to look at moving luminous dots that form a human figure, rather than dots that move similarly but are randomly placed (Fig. 10).
We pay special attention to the eyes of other people. When we follow someone's eyes, we catch their slightest movements. This sensitivity to eye movements allows us to take the first step into the inner world of another person. From the position of his eyes, we can tell quite accurately where he is looking. And if we know where a person is looking, we can find out what he is interested in.
We not only unwittingly look at what others look at. Our brain has a tendency to automatically repeat any movement that we see. Giacomo Rizzolatti and his colleagues conducted experiments in Parma on the neurons involved in the grasping movements of monkeys. To the researchers' surprise, some of these neurons didn't just fire when the monkey touched something. They were also activated when the monkey saw one of the experimenters take something with his hand. Such neurons are now called mirror neurons. The same is true for the human brain.
Imitation is like prediction. We have a tendency to imitate others automatically without thinking about it. But imitation also gives us access to the personal inner world of others. We imitate not only the rough movements of the arms and legs. We also automatically imitate the subtle movements of faces. And this imitation of other people's faces affects our feelings. Due to the fact that we can build models of the material world, we are able to share the sensations of the inner world of other people.
Our ability to create models of the inner world entails some problems. Our picture of the material world is a fantasy, limited by the signals coming from the senses. In the same way, our picture of the inner world (our own or other people) is a fantasy, limited by the signals we receive about what we ourselves say and do (or about what others say and do). When these restrictions fail, we have illusions about what we do and see.
PART THREE. Culture and brain
Chapter 7
The most remarkable achievement of our brain is undoubtedly its ability to provide communication between the minds of different people. I have an idea in my head that I would like to share with you. I do this by translating the meaning of this idea into spoken language. You hear my speech and again transform it into an idea in your head. But how do you know that the idea in your head is the same as the one in my head?
The problem of words and meanings is a more complicated version of the problem of movements and intentions. When I see movement, I capture the intention behind it. But the meaning of the movements is ambiguous. Many different goals require the same movements. Engineers would call this search for meaning an inverse problem. Our hand is a simple mechanical device that engineers can understand. It is based on solid rods (bones) connected by joints. We move the arm by applying muscle power to these rods. What happens when we apply a force to this system in a certain way? The search for an answer to this question is called the direct problem. This problem has a unique solution.
But there is also an inverse problem. What forces do we need to apply if we want our hand to take a certain position? This problem does not have a single solution. We solve exactly the same inverse problem when we listen to human speech. To express many different meanings you can use the same words. How do we choose the best of these meanings? We (more precisely, our brain) make assumptions about what goals this or that person can pursue, and then predict what he will do next. We assume that a person is trying to tell us something, and then we predict what he will say next.
Where do our assumptions begin? Assumptions about people about whom we do not yet know anything can only be based on prejudice. This is nothing but prejudice. Prejudices give us the opportunity to start making assumptions - no matter how accurate our guess turns out to be, as long as we always adjust our next guess according to the error we discover. Prejudice is built into our brains by evolution. We have an innate tendency to prejudice. All our social interactions begin with prejudice. The content of these prejudices is obtained from interactions with friends and acquaintances, as well as from rumors.
Our prejudices start with stereotypes. Our first a priori beliefs about the likely knowledge and behavior of strangers are related to their gender. Even three-year-old children have already developed this prejudice.
Social stereotypes give us a starting point for interactions with strangers. They allow us to make first guesses about the intentions of these people. But we know that these stereotypes are very primitive. The assumptions and predictions we make based on such limited knowledge will not be very good.
Communication in the form of a dialogue, face to face, is not a one-way process, unlike reading a book. When I have a dialogue with you, depending on your reaction to me, my reaction to you changes. This is the cycle of communication.
We understand that people's behavior is driven by beliefs, even if those beliefs are false. And we quickly learn that we can control people's behavior by giving them false information. This is dark side our communication. Without the realization that behavior can be controlled by beliefs, even if those beliefs are false, deliberate deceit and lying would be impossible. At first glance, a person's inability to lie may seem like a nice, pleasant quality. However, often such people are lonely and have no friends. Friendships are actually maintained through many little lies and evasive answers that allow us to sometimes hide our true feelings. At the other extreme, people suffering from paranoia are represented, any message can be a deception or a hidden message that requires interpretation.
True. Our knowledge of the world is no longer limited to the experience of one lifetime - it is passed down from generation to generation. I believe that truth exists. As long as we can be convinced that one model of the material world works better than another, we can strive to create a series of more and more successful models. At the end of this series, although it is infinite in the mathematical sense, is the truth - the truth of how the world really works. The achievement of this truth is the task of science.
That is why the belief of some philosophers in the purity of sensory perception is devoid of practical meaning. There is simply no such thing as "sense perception". Perception is always preceded by theory.
What a pity that we prefer email to dialogue.
Rated the book
Rated the book
A rather simple and unpretentious book "about the brain", quite advanced, but at the same time very lightweight. The author seems to be such a clumsy bum, afraid of his imaginary opponents - the bearer of the humanitarian consciousness of the professor of literature (for sure, that still spectacular little thing) and the aggressive professor of physics, responsible for the attack on the conclusions of all these neuropsychologies from the exact sciences. In principle, this can be understood - this area is really severely interdisciplinary (that is, it is lame on both legs, my inner skeptic tells me), and few people like the results of its activities, since they are very inconvenient. So the author has to literally crawl on the ground on his own, dodging humanitarian howls and caustic attacks (alas, often justified) and trying to lure a not very educated reader into his science. If you have already read something about the brain there or are generally interested in current situation cases in brain science, interesting new discoveries do not shine for you here. But if you are a beginner and your ideas about how hard the body can deceive itself are limited to simple optical illusions, then you are here. Well, a brief summary: our life is just a dream, but 16 hours a day its content is quite close to objective reality.
Rated the book
I knew! I knew, I knew, I knew! I have always known that my brain and I are completely different personalities and often with opposite desires. If you also thought that you and someone inside your skull were different personalities, don't worry. This is not schizophrenia, but a well-proven scientific fact.
Over the course of three hundred pages, the author explains, with references to scientific research, that every person has a "gray cardinal" in the skull. He paints a picture of the world for us, and with great reluctance admits the mistakes he made in the process, he decides what we will do and convinces us that this is what we did, even if this is obviously not the case. The author will give a sufficient number of examples from scientific practice showing that even if we realize the fallacy of the picture of the real world that our “manager” has drawn for us, we will need to spend a lot of time and make certain efforts to prove it to our own brain.
Fritt will quite colorfully prove that everything we know about the reality around us is nothing more than an illusion drawn for us by our brain. And not even always based on signals from the senses. The brain follows the path of the greatest acceleration of the work performed and often finishes the picture simply on the principle of the greatest probability, based on previous experience. So if you suddenly see a flying lilac giraffe outside the window, you will have to argue for a long time with those who are sitting inside the skull and prove that consciousness and vision have not gone crazy. The brain, by the way, will resist and impose its own point of view on these issues. As about the lilac giraffe, and about your own sanity.
Of course, it's not that bad. After all, the brain solves more tasks every second than modern computers could ever dream of. Few people think that absolutely every movement, even the smallest, up to microscopic changes that allow you not to fall when walking, is sanctioned by the brain. Constant flow information is processed, analyzed and transformed into signals for the rest of the body. And only a few percent of this our brain considers it necessary to bring to the attention of our consciousness. If we were to receive this data in full, we would go crazy pretty quickly.
This book is not exactly about psychology, as most people understand it, but rather about neuroscience. The author, although he calls himself a psychologist, is much more interested in the physiology of the brain and the processes that occur in it during any activity, both intellectual and physical. That area of science, which most readers call psychology, the author passes over in silence. Although he does not do without some digressions into the history of psychology and psychiatry, and quite regularly goes to Sigmund Freud and his theory. Obviously, Chris Frith dislikes both Freud's theory and Freud himself with all his followers, up to the modern ones. He goes to great lengths to prove that Freudianism is unscientific, erroneous, based solely on assumptions, and generally has nothing to do with psychology in general and Chris Fritt in particular. Well, everyone can have their own opinion on this issue.
The area of scientific interests of Fritt himself lies in the field of higher nervous activity. The book contains many cross-sectional pictures of the brain, in which the reader is shown exactly where the cells will be activated when performing this or that activity, during reflections, fantasies, and the like. In addition, he gives a large number of examples from practice, showing various consequences brain disorders or damage to various areas of the brain.
This book good way a little better to understand how the organ of our body is arranged and how it functions, which, in fact, makes a person a person. Realize how much work he does non-stop throughout his life. But still, if you see a flying lilac giraffe outside the window, do not rush to call an ambulance, even if the brain has already given the hands the command to grab the phone.
The book was published by the Astrel publishing house in the Elements series of the Dynasty Foundation (this is such an inter-publishing series of scientific literature), a circulation of 5000 copies. Subtitled How Nervous Activity Shapes Our Inner World. (Chris Frith. Making Up the Mind. How the Brain Creates our Mental World.)
In the Dynasty series, I have not yet come across uninteresting books, and then there is also a popular science book on psychology, which is rare (after all, Carnegie and the like have nothing to do with psychology as a science).
I was not disappointed. In a sense, this book rehabilitated psychology for me as a science, and even as a natural science, analogous to physics, chemistry, and biology. And that psychology and Freudianism are different things. (" In order not to spoil my evening, I refrain from suggesting that Freud was an inventor, and that his discourses on the human psyche are of little relevance to the case."). Unfortunately, Freudianism and other “vulgar psychology” have become so ingrained in the public consciousness that the author himself prefers to present himself as a “cognitive neuroscientist.” This book is a story about what they really do.
It turns out that psychologists are actively using the latest tools - various tomographs - to objective research processes taking place in the brain. And now on tomographs you can observe not only photographs of the brain, but also see the process of activation of various parts of the brain in dynamics. And thanks to this, you can, for example, see that if a person imagines a face in his head, then the same parts of the brain are activated, as if he saw this face in reality. However, tomographs are only one of the tools.
It turns out that our brain does not tell us anything about many things. For example, they studied a woman who had carbon monoxide poisoning, as a result of which the part of the brain responsible for the perception of form was damaged. She could dimly see light, color, and shadows, but she couldn't recognize anything. She was given a stick, and asked how she was given a stick - vertically or horizontally. The woman, of course, could not say this, she did not see it. But when she was asked to take a stick, she correctly extended her hand, depending on the horizontal or vertical position. It turns out that the brain saw the stick, but did not want to share this information with consciousness at all.
The book tells about a lot of experiments, including quite simple ones (for some reason, I didn’t know how to detect a blind spot, I was impressed by the loss of a finger). In general, we do not directly receive any information about the world around us. We communicate only with our brain, and it builds representations about the world around us, and it adds a lot, finishes it, very much. great importance have brain attempts to predict the world around them. Hence, by the way, optical illusions, and hallucinations too. But from here comes the feeling of empathy, the ability to understand what another might feel.
Interestingly, the author very carefully avoids the issue of free will, about how much a person can rule over his brain. It seems that this question is still out of science. The key word is "yet". (By the way, in the original English title There is no "soul" in the book!
As a summary: it's a pity that such few books on psychology. And what is the big difference between what psychology really studies and the ordinary idea of psychologists. I even have doubts that we really train psychologists at the psychology departments of universities. More books like this!
Chris Frith (Christopher Donald Frith, born in 1942 in England) is an eminent British neurophysiologist, working primarily in the field of neuroimaging.
Since 2007 - Distinguished Professor at the Center for Neurodiagnostics at University College London (Wellcome Trust Center for Neuroimaging at University College London) and Visiting Professor at the University of Aarhus (Denmark). The main scientific interest is the use of functional neuroimaging in the study of higher human cognitive functions.
Studied natural sciences at the University of Cambridge, in 1969 he defended his thesis in experimental psychology.
Author of over 400 publications, including seminal books in neuroscience such as the classic The Cognitive Neuropsychology of Schizophrenia (1992). The popular science book Making Up the Mind (2007) was longlisted for the Royal Society Science Book Award.
Books (2)
Schizophrenia
Schizophrenia - a common mental illness - spoils the life of one in a hundred people, has a devastating effect on those who suffer from it and on their families.
This book tells what the disease really looks like, how it progresses and how it can be treated. The authors of the book summarized the data of the most recent studies biological basis schizophrenia.
Brain and soul
Brain and soul. How nervous activity shapes our inner world.
The famous British neuroscientist Chris Frith is well known for his ability to talk simply about very complex problems of psychology - such as mental activity, social behavior, autism and schizophrenia.
It is in this area, along with the study of how we perceive the world around us, act, make choices, remember and feel, that today there is a scientific revolution associated with the introduction of neuroimaging methods. In Brain and Soul, Chris Frith talks about all this in the most accessible and entertaining way.
Reader Comments
Gurka Lamov/ 11/10/2016 No matter how large the number of material (brain) correlates of the functioning of consciousness is, none of them explains the cause of these dependencies. For example, to explain the existence of such dependences by the origin of consciousness from the material activity of the brain is only one of the possible hypotheses. Other reasons can be imagined that are just as legitimate.
Alexei/ 06/30/2010 A good popular science book. How is disease defined? The history of the concept of schizophrenia. Causes of occurrence and scientific search for a solution to this problem. The book is small (200 pages) and will be useful and understandable to an unprepared reader.