Chapter 4 Chapter 2 The Nature of Consciousness

"Find the most amazing thing in any field, and study it." - Wheeler (John Archibald Wheeler) To study the question of consciousness, we must first know what needs to be explained.Of course, we all know in general what consciousness is.But sadly, that alone is not enough.Psychologists have often shown us that common sense about mental activity can lead us astray, and the obvious first step is to clarify what psychologists have believed to be the essential characteristics of consciousness for many years.Of course, their views may not be entirely correct, but at least some of their thoughts on this issue will provide us with a starting point.

Since the question of consciousness is so important and mysterious, one would naturally expect that psychologists and neuroscientists should devote their major efforts to the study of consciousness.But the truth is far from it.Most modern psychologists shy away from addressing this issue, even though much of their research involves consciousness.Most modern neuroscientists ignore this question entirely. This wasn't always the case either.Around the end of the nineteenth century, when psychology began to be an experimental science, there were many people who were very interested in the question of consciousness.Although the exact meaning of the word was not known at the time.The main method of studying consciousness at that time was detailed and systematic introspection, especially in Germany.It is hoped that psychology will become more scientific through its careful refinement before introspection becomes a reliable technique.

The problem of consciousness was discussed at some length by the American psychologist William James (brother of the novelist Henry James), who described what he called the Five characteristics of "thought".Every thought, he wrote, is part of the individual consciousness.Thoughts are always in flux, feel continuous, and seem to deal with issues that have nothing to do with themselves.Also thought can focus on certain objects and move away from others.In other words, it involves attention.Concerning attention, he wrote oft-quoted: "Everyone knows what attention is, the use of intention to select, in a clear and distinct manner, one of several simultaneously possible objects or trains of thoughts. One ... which means leaving some things in order to deal with others more efficiently."

In the 19th century, we can also find the idea that consciousness is closely connected with memory; James once quoted the Frenchman Charles Richet (Charles Richet) in 1884: "The pain of a moment is so small that for me I would rather suffer Pain, even if it is severe, as long as it lasts for a short time, and, after the pain has passed, never reappears and disappears from memory forever." Not all operations of the brain are conscious.Many psychologists believe that there are some subconscious or subconscious processes.For example, the nineteenth-century German physicist and physiologist Hermann von Helmholtz frequently used the term "unconscious inference" when referring to perception, in order to show that, in the logical structure In essence, perception is similar to what is usually expressed by inference, but it is basically unconscious.

In the early 20th century, the concepts of the preconscious and the unconscious became very popular, especially in literature.This is mainly because Freud, Jung, and their collaborators gave literature a certain sexual flavor.According to modern standards, Freud can not be regarded as a scientist, but should be regarded as a doctor with many new ideas and many excellent books.Because of this, he became the founder of the psychoanalytic school. As early as a hundred years ago, three basic views had prevailed: 1.Not all operations of the brain are associated with consciousness. 2.Consciousness involves some form of memory, possibly short-term memory.

3.Consciousness is closely related to attention. Unfortunately, however, there has been a movement in psychological research to deny the practical value of consciousness as a purely psychological concept, partly because experiments involving introspection are no longer the mainstream of research. , on the other hand, people hope that by studying behavior, especially the behavior of animals, the study of psychology will be more scientific.For, to the experimenter, behavioral experiments have definite observations.This is the behaviorist movement, which shies away from talking about psychic events.All behavior must be explained in terms of stimuli and responses.

john.The behaviorist movement initiated by John B. Watson and others before the First World War became popular in the United States, and due to the influence of many famous advocates represented by BFSkinner, the movement peaked in the 1930s and 1940s.Psychologists, at least in the United States, never talked about mental events until cognitive psychology became a scientifically respected discipline in the late 1950s and 1960s, although there was still a school of psychology represented by Gestalt in Europe .After this, it was possible to study visual imagery and to propose psychological models of various mental processes on the basis of concepts originally used to describe the behavior of digital computers.Even so, consciousness is rarely discussed, and few attempts are made to distinguish between conscious and unconscious activity in the brain.

The same is true when neuroscientists study the brains of experimental animals. Neuroanatomy almost always studies animals after death (including humans), while neurophysiologists mostly only study animals that are unconscious after anesthesia. Have any painful sensations anymore.This is especially the case after the epoch-making discoveries made by David Huber1 and Torsten Wiesel in the late 1950s.They had discovered that nerve cells in the visual cortex of an anesthetized cat's brain exhibited a series of interesting response properties to the light patterns that a person shone into their eyes.Although the brain waves showed that the cat was sleeping rather than awake at this time.For this discovery and subsequent work, they were awarded the 1981 Nobel Prize.

It is even more difficult to study the characteristics of the brain response of animals in the awake state (in this case, not only the head movement needs to be restrained, but the eye movement must also be prohibited or recorded in detail).Therefore, few people have done experiments comparing the response characteristics of the same brain cells to the same visual signal in both waking and sleeping states. Traditional neuroscientists avoid the problem of consciousness not only because of experimental difficulties, but also because They thought the question was too philosophical to observe experimentally.Funding is difficult for a neuroscientist who wants to study consciousness specifically.

Physiologists have hitherto been less concerned with the question of consciousness, but in recent years some psychologists have begun to do so, and I will briefly describe the views of three of them.What they all have in common is their neglect or lack of interest in nerve cells.Instead, they primarily want to contribute to the understanding of consciousness using standard psychological methods.They view the brain as an opaque "black box" of which we only know the outputs (the behaviors it produces) from its various inputs (such as sensory inputs).They build models based on commonsense knowledge of the mind and certain general concepts.The model uses engineering and computing terms to express the spirit.The above three authors might label themselves cognitive scientists.

Philip Johnson-Laird, now Professor of Psychology at Princeton University, is a distinguished British cognitive psychologist.His main interest is the study of language, especially the meaning of words, sentences and paragraphs.This is a human-only problem, and it's not surprising that Laird paid little attention to the brain.Because our main information about the primate brain comes from monkeys, which have no real language, his two books, Mental Models and The Computer and the Mind, ) focuses on the problem of how to describe the mind (the activity of the brain) and the relationship of modern computers to this description.He emphasized that the brain is highly parallel (that is, tens of thousands of processes can be carried out simultaneously), but it does most of the work we are not aware of. ① Johnson-Laird was convinced that any computer, especially a highly parallel computer, must have an operating system that controls, if not completely controls, the rest of the work. There is a close connection between the consciousness of the higher parts. Rav Jackendoff, professor of linguistics and cognition at Brandeis University, is a well-known American cognitive scientist.He has a special interest in language and music.Like most cognitive scientists, he argues that the brain is best viewed as an information-processing system.But unlike most scientists, he regards "how consciousness arises" as one of the most basic problems of psychology. His Intermediate-Level Theory of Consciousness believes that consciousness comes neither from raw perception units nor from high-level thoughts, but from the lowest peripheral (similar to sensation) and A level of expression between the highest centers (similar to ideas).He rightly highlights this very novel point of view. Like Johnson-Laird, Jackendorf was largely influenced by the analogy between the brain and modern computers.He pointed out that this analogy can lead to some immediate benefits, such as computers storing a lot of information, but only a small part of the information is active at any one time.The same is true in the brain, However, not all activity of the brain is conscious.Thus, he makes a strict distinction not only between the brain and the mind, but also between the brain (computational thinking) and the so-called "phenomenological mind" (roughly referring to what we are aware of).He agrees with Laird that we are aware of the results of calculations, not the calculations themselves. ① He also believed that there was a strong connection between consciousness and short-term memory.His statement that "consciousness needs the content of short-term memory to support" expresses such a point of view.But it should also be added that short-term memory involves fast processes, whereas slow-changing processes have no direct phenomenological effects. When talking about attention, he believes that the calculation effect of attention is to make the material under attention undergo more in-depth and meticulous processing.This, he thinks, explains why attentional capacity is so limited. Both Jackendorf and Johnson-Laird were functionalists.Just as one does not need to know the actual wiring of a computer to program a computer, functionalists study the brain's information processing and the computations it performs on that information without taking into account the neurobiological realization of these processes.Such considerations, they argue, are irrelevant, at least for now, premature. ① However, this attitude does little good when trying to uncover the workings of an extremely complex device like the brain.Why not open the black box and observe the behavior of each unit in it?It is unwise to tie one hand behind your back when dealing with a complex problem.Once we understand certain details of how the brain works, the high-level descriptions that functionalists care about become a useful way to think about the behavior of the brain as a whole.The validity of this idea can be precisely tested with detailed data obtained at low levels of cells and molecules.High-level tentative descriptions should be seen as initial guides to help us unravel the complex operations of the brain. Professor Bernard J. Baars of the Wright Institute in Berkeley, California, wrote "A Cognitive Theory of Consciousness." Although Baars is also a cognitive scientist, he is not the same as Jackendorf or Johnson-Laird cared more about the human brain than he did. He called his basic idea the Global Workspace (Global Workspace).He believes that the information that exists in this workspace at any moment is the content of consciousness.As a working space for central information exchange, it is connected to many unconscious receiving processors.These specialized processors are efficient only within their domain.In addition, they can also obtain work space through collaboration and competition.Bales improved this model in several ways.For example, receiving processors can interact to reduce uncertainty until they conform to a uniquely valid interpretation. (l) Broadly speaking, he argued that consciousness is hyperactive and that attentional control mechanisms are accessible to consciousness.We are aware of some items of short-term memory but not all. These three cognitive theorists generally agree on three things about the properties of consciousness.They all agree that not all activity of the brain is directly related to consciousness, and that consciousness is an active process; they all agree that attention and some form of short-term memory are involved in the conscious process; Access to long-term episodic memory also provides access to the higher planning levels of the motor system to control voluntary movement.In addition, there are differences of one kind or another in their thinking. Let's keep these three ideas in mind and combine them with our growing knowledge of the structure and activity of nerve cells in the brain to see what such an approach can yield. Most of my own ideas were formed in collaborative research with my younger colleague, Christof Koch, associate professor of computing and neural systems at Caltech.Koch and I met in the early 80s when he was a graduate student of Tomaso Poggio in Tubingen (German city).Our explorations are scientific in nature. ②We believe that general philosophical debates are not helpful to resolve the problem of consciousness.What is really needed are new experimental approaches that promise to address these issues.In order to do this, we also need a tentative body of thought that is continually refined and discarded as our work progresses.A scientific method should be characterized by not attempting to build an all-encompassing theory that explains all aspects of the problem of consciousness at once.Nor can the research focus on language, because only humans have language.Instead, we should choose the system that seems most beneficial to the study of consciousness at the time, and study it from as many aspects as possible, just as in war, it is usually not to take an all-out attack, but to find the weakest point and concentrate its forces To break through. We made two basic assumptions.The first is that we need a scientific explanation for something.Although it may be debated which processes are conscious, there is general agreement that people are not conscious of all the processes that take place in the mind.While you are aware of the results of many perceptual and memory processes, you may have limited understanding of the processes that produced that awareness. (For example, "How did I remember my grandfather's name?") In fact, some psychologists have suggested that you have only a limited capacity for introspection about the origins of even higher cognitive processes.At any given moment, there may be some active neural processes associated with consciousness, while others are not.What is the difference between them? Our second hypothesis is tentative: all the different aspects of consciousness, such as pain sensation and visual awareness, use an underlying common mechanism or perhaps several such mechanisms.If we can understand the mechanics of one of these, we can hopefully understand the mechanics of all the others.Paradoxically, consciousness seems so outlandish, and at first glance so impenetrable, that only some rather peculiar explanation is possible.The general nature of consciousness may be easier to discover than some of the more common operations.How the brain processes three-dimensional information can in principle be explained in many different ways.Whether this is true remains to be seen. Christopher and I believe that certain issues can be set aside or simply stated without further discussion.Because, experience tells us, if this were not the case, a lot of precious time would be wasted in endless arguments. 1.Everyone has a rough idea of ​​what consciousness is.Therefore, it is best not to give it a precise definition, because it is dangerous to define it prematurely. Before a deeper understanding of this issue, any formal definition may cause misunderstanding or be too restrictive: ① 2.It is too early to debate in detail what consciousness is, although such a discussion may help to understand its properties.After all, it is strange to think too much about the function of something when our definition of it is vague.It is well known that without awareness you can only process familiar everyday situations, or respond to very limited information in new situations. 3.Certain kinds of animals, especially higher mammals, may have some, but not all, of the important features of consciousness.Therefore, proper experiments with these animals can help to reveal the inner mechanism of consciousness.Thus, language systems (of the type that humans have) are not essential to consciousness, that is, key features of consciousness can still be present without language.Of course, this is not to say that language does not play an important role in enriching consciousness. 4.At this stage, it is useless to debate whether certain lower animals such as octopuses, fruit flies or nematodes are conscious.Because consciousness may be related to the complexity of the nervous system.When we have a clear understanding of human consciousness both in principle and in detail, this is when we consider the question of consciousness in the very lower animals. For the same reason, we do not ask the question whether parts of our own nervous system have their own special, isolated consciousness.If you're going to say, "Of course my spinal cord is conscious, it just doesn't tell me." Well, at this stage, I won't spend time arguing with you about that. 5.Consciousness takes many forms such as those associated with seeing, thinking, emotions, pain, etc.Self-awareness, that is, awareness with respect to oneself, may be a special case of consciousness.According to our point of view, it is better to put it aside for the time being.Certain rather abnormal states, such as hypnosis, daydreams, sleepwalking, etc., have not been considered here, since they have no special features which would be of advantage to the experiment. (1) If this seems like a bluff, you might as well define the word gene for me. Although we have learned a lot about genes, any simple definition is probably not sufficient. We know how difficult it is to define a biological term when we know very little about a problem. How can we study consciousness scientifically?Consciousness takes many forms.As we have already explained, initial scientific inquiries usually focus on the forms that seem easiest to study.The reason Koch and I chose visual awareness over some other form of pain awareness or self-awareness is that humans depend so much on vision.Moreover, visual awareness is particularly vivid and informative.In addition, its input is highly structured and easy to control.It is for these reasons that much experimental work has revolved around it. Vision systems have additional advantages.For ethical reasons, many experiments cannot be performed on humans, but can be performed on animals (this will be fully discussed in Chapter 9). Fortunately, the visual system of higher primates seems to have some similarities with humans. some similarities.Many vision experiments have been done in primates such as rhesus monkeys.If we had chosen language systems to study, we would not have suitable experimental animals. Thanks to our detailed knowledge of the visual system of the primate brain (discussed fully in Chapters 10 and 11), we know how the various visual parts of the brain resolve images of the visual field.But we don't yet understand how the brain puts them together to form the highly organized landscape of the outside world that we see.It appears that the brain has superimposed a certain unity of the whole on the neural activity of the visual parts.In this way, the various attributes of an object (shape, color, motion, position, etc.) can be assembled together so that they are not confused with other objects in the field of view. The mechanism required for this global process is best described by "attention" and also involves some form of short-term memory.It has been suggested that this global unity can be expressed in terms of relative firing of the neurons involved.Roughly speaking, this means that neurons responding to a property of an object tend to fire synchronously, while neurons responding to other objects fire asynchronously with this set of related firings (this will be discussed in the fourteenth, Discussed fully in Chapter 17), in order to explore this question we need to know something about the psychology of vision. ① Johnson-Laird was particularly interested in self-response and self-awareness.For strategic reasons, these issues are set aside. ① Jackendorf expresses this with his own postscript.He calls what I call "results" "information structures". ① Genetics is also concerned with the transmission of information between generations and within individuals.But the real breakthrough came when the structure of DNA made clear the message expressed by the idiom. ① I do not want to dwell on all the complexities of Baars' model.In order to explain various aspects of the problem of consciousness such as self-awareness, self-monitoring, and some other mental activities such as unconscious out-of-context, volition, hypnosis, etc., many complexities were added to his model. ②In what follows I will quote extensively from Koch's and my thinking in an article on this issue published in the journal Seminars in the Neurosciences (SIN) in 1990.