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The Biology of Mind - Origins and Structures of Mind, Brain, and Consciousness

M. Deric Bownds.

Table of Contents

Preface 2

Chapter 1: Thinking About Thinking 5

How Do We Define Mind and Consciousness?

Awareness

Introspection and Reflection

How Does Consciousness Emerge from a Brain/Body?

Defining the Problem

Assembling an Explanation

Organism and Environment

Where Is the "I"?

Part I - Evolving Mind

Chapter 2: Origins of Mind 13

Origins of Sensing and Acting

Simple Forms of Behavior

Communication Between Cells

Reflexes and Interneurons

Evolution of the Nervous System

Adaptations and Increasing Complexity

Biological Diversity

Origins of Minds, Perceptions, and Affect

The Simplest Form of Mind

Consciousness and the Evolution of Sensory Organs

Perceptions and New Behaviors

Chapter 3: Structures of Mind 28

Origins and Structures of the Vertebrate Nervous System

Layers of the Brain

The Cerebral Cortex

Modern Studies of Brain Function

Association of Functions with Different Brain Regions

Specializations of the Cerebral Hemispheres

Imaging the Activity of the Brain

Chapter 4: Primate Mind 41

The Question of Animal Consciousness

Transitions from Monkeys to Hominids

Upright Posture

Larger Brains

Stages in Hominid Emergence

Origins of Human Intelligence

Episodic Intelligence

The Great Apes: Selves and Others

Socialization and Other Skills Among the Chimps

Developing a Concept of Self

Awareness of the 'Mental States of Others

Chapter 5: Hominid Mind 53

The Mimetic Intelligence of Early Hominids

Kinesic Communication

Social Cohesion and Body Languages

Origins of Language

Internal Narrative

Language as an Adaptation

Evolution of Brain Structures Supporting Language

Language and the Evolutionary Tree

The Emergence of Modern Humans

Evidence for the Out-of-Africa Hypotheses

Co-evolution of Humans and Their Tools

The Origins of Mythic Intelligence

What Caused the Transition to Upper Paleolithic Culture?

Evolutionary Psychology---The Search for a Universal Mind

Genetic Arguments for an Evolved Psychology

Evolution of Cooperation

Evidence from Cross-Cultural Studies

Listing and Evaluating Human Universals

The Evolution of Ideas and Customs

The Concept of Memes

Evolution of Memes

Part II - Developing Mind

Chapter 6: Plastic Mind 70

An Outline of Brain Development

Origins of Plasticity

A Hierarchy of Developmental Circuits from Innate to Learned

The Wiring of Developing Brains

Pathways to the Cerebral Cortex

Plasticity in Forming the Visual Cortex

Experience Guides the Formation of Successful Connections

Adult Brains Can Change Their Nerve Connections

Expansion and Contraction of Cortical Areas

Cortical Plasticity and the Phantom Limb Phenomenon

Social Experience Can Alter Brain Structure

Limits of Brain Plasticity

Memory Is a Form of Brain Plasticity

Long-Term Memory

Models of Recognition and Memory

Procedural Memory

Olfactory Memories

The Sexual Brain---Plasticity Induced by Hormones

Hormonal Influences on Behavior

Hormonal Influences on Visuospatial Skills

Chapter 7: Minds and Selves 90

Stages in the Development of Human Selves

Effects of Rich Versus Impoverished Environments

The Role of Language

The Cerebral Hemispheres as Selves

Self Boundaries

Selves Are Modular Constructions

The Example of Musical Intelligence

How Many Selves to a Customer?

Selves, Genes, and Environments

Framing the Issue of Nature and Nurture

Physical Environments and Selves

Cultural Influences on Self

The Relativity of Thought Systems

Part III - Society of Mind

Chapter 8: Perceiving Mind 102

Ecology of Sensing and Acting

Perception Focuses on Change

Perception Is Filtered and Directed by Many Factors

Distinguishing Between Sensation and Perception

Perception of Spatial Relationships

Visual Systems

Self-Experiment: A Look at Vision and Its Muscular Correlates

Our Visual Brain

Visual Information Is Processed in Parallel Streams

Form, Motion, and Color

The "What" and "Where" Systems

Visual Pathways Outside the Cortex

Ensembles of Cells Encode Faces and Other Icons

Information Streams Flow Forward, Backward, and Sideways

A Binding Process Underlies Visual Perception

Neural Correlates of Visual Consciousness

Chapter 9: Acting Mind 120

Action---The Interface of Mind and Environment

A Movement-Oriented View of Mind and Consciousness

Kinesthetic Intelligence

Action Repertoires

Parallel Actions

Movement Exercises That Reveal Underlying Mechanisms

Neuronal Pathways Underlying Action

Movement Generation by Darwin Machines

Chapter 10: Emotional Mind 130

Defining Emotions

Emotions Are Evolutionary Adaptations

Emotions and the Physical Environment

Emotions and Social Exchange

Subcortical Systems Underlying Emotions

The Autonomic Background of Emotions

Brainstem Modulation of Attention and Appetite

Other Correlations of Chemistry and Emotional Behavior

Higher Levels of Emotional Mind

Emotional Mind as a Foundation of Rational Mind

Lateral Organization of Emotions

Emotional Responses Can Be More Rapid Than Reasoned Ones

Central Role of the Amygdala

Perception of Emotional and Cognitive Pathways

Facial Musculature and the Communication of Emotions

Misapplication of Ancestral Emotions---The Chronic Stress Response

Chapter 11: Linguistic Mind 149

The Language Instinct

Universal Language

The Case of Language as an Evolutionary Adaptation

The Learning of Language

Genetic Determinants of Language Ability

Language Development and Brain Structure

Language Development as Invention

Brain Mechanisms of Language

Multiple Language Areas in the Cortex

Language as Accessory to Other Fundamental Brain Mechanisms

Metaphor and the Construction of Language

Part IV - Modern Mind

Chapter 12: Conscious Mind 159

The Mind/Body Problem

Can the Problem of Consciousness Be Solved?

The Machinery of Awareness

The Brain's Time and Space: The Disappearance of "I"

Plastic Representations of Time and Space

The Futility of Asking "Where Does It All Come Together?"

Sleep and Other Altered States of Consciousness

Stages of Sleep and Dreaming

Mystical Experiences

Humor and Laughter

Neural Correlates and Models of Consciousness

Brain Structures Required for Conscious Awareness

Generating an Apparent "I"

Introspection and the Self System

Computer Metaphors

Chapter 13: Theoretic Mind 174

Emergence of the Modern Mind

Graphic Invention

Early Theoretic Societies

Merging of Individual Minds and External Memory Stores

Parallel Expression of Ancient and Modern Minds

Conflict of Paleolithic and Modern Minds

Paleolithic Adaptations

Mythic Components of Modern Intelligence

Addressing Pluralism

Ancient and Modern Minds in an Electronic Age

Future Mind

Teleological Schemes

The Theme of Encapsulation

The Evolution of Evolution

Bibliography 185

Preface

 

Until recently the study of mind, consciousness, and feelings has been a subject for philosophy and religion, outside the province of hard science. This has changed in just the past few years, as advances in anthropology, animal behavior, evolutionary theory, linguistics, molecular neurobiology, psychology, and cognitive neuroscience have brought us to the threshold of resolving questions that have occupied philosophers for millennia:

 

 

"How does the human brain generate a "self"?

"What is the nature of the narrative "I" that we experience in our heads?

"What is the relationship between reason and emotion?

"How do genetic and environmental factors interact to determine the structure of our brains?

 

 

Interdisciplinary approaches to these questions are making it possible to construct models of mind and emotion that are amenable to experimental tests. The message of this book is that each of us is a society of minds that emerge from our evolutionary history and from the way our brains form as we grow up in a particular natural ecology and cultural setting. Each chapter contributes a few perspectives on the society of mind that forms, describing a subset of its elements. From our evolutionary history we derive the genetic instructions with which we begin life, and the particular mind and brain that each of us then grows are shaped and patterned by our surroundings. There are many roads to understanding our minds, many different windows through which we must peer. We approach the target from different directions when we take up the perspectives provided by neurobiology, cognitive psychology, animal behavior, linguistics, and evolutionary biology. We need to consider successive glimpses of different aspects of "mind." There are many ways to model ourselves, multiple versions of "this is I." We can utilize information on how our nervous systems evolved over millions of years, as well as high-technology gadgets designed to peer inside our brains as they work. This book tries to mix these two approaches---to assemble a description of our minds as a vast collective of agents that interact to construct an unconscious background out of which a narrative "I" emerges. You may well discover that the new ideas we suggest change your everyday perceptions and actions.

 

This writing began for the purpose of supporting a course for both science and non-science majors at the University of Wisconsin in Madison. It has proved useful in offering a continuous background, overview, and storyline that supports presentation of current work in each of the areas covered. Each chapter provides the core material for 1 to 3 of the approximately 45 lectures in a standard semester. This present book is an effort to share with a wider audience some of the fascination and excitement that have permeated both public and university lectures on the subjects it addresses. It falls somewhere in between a traditional academic text and a popular account. You will have an easier time with the book if you have had an introductory high school or college biology course. Sidebars are used at intervals to emphasize main points or self-exercises. At the end of each chapter is a summary, followed by thought questions and suggestions for further reading. Key words are italicized and defined in a glossary at the end of the book. If you would like more information on a particular subject that interests you, the references provided for each chapter should enable you to pursue the matter further. Detailed citations that support many of the factual statements made in the text can be found in a draft of this book on the World Wide Web at http://mind.bocklabs.wisc.edu.

 

In parts of this book, topics have been grouped in a way that corresponds to our subjective living experience, things we do every day---hence the chapters on perceiving mind, acting mind, emotional mind, and linguistic mind. The ideas can become more real and interesting if we use our subjective experience to engage them, and occasionally simple exercises are suggested to illustrate some of the mechanisms we consider. Such exercises can be instructive and fun if we don't lose sight of two points. First, what we think and feel is just the tip of the iceberg, compared with what is really going on in our brains. What we are aware of is something like the display on a computer screen as distinguished from the inner working of the computer. Second, our subjective experience can be very biased and distorted by factors of which we are unaware. Numerous psychological experiments have documented that our perceptions are not necessarily naive, reporting actual events outside or inside our bodies. Rather, they can be influenced by what we or someone else expects us to perceive. This is why traditional scientific inquiry insists on eventually putting our subjective insights into a form that can be tested impersonally by independent observers. Each of us can imagine that a particular process is going on inside our head, but it will remain thoroughly hidden there until its presence can be inferred from a third-person experimental demonstration.

 

This book encourages you to weave, through its ideas about how our minds work, a fabric of your own personal experience, feeling the richness deepen as these ideas inform your introspection about the mechanisms of your thinking, feeling, and acting. Our brains can rearrange space, time, thoughts, and emotions. Some of these processes can be made accessible to our awareness through simple mental exercises. It is not too difficult to sense motor programs of which we are usually unaware, to separate thoughts from emotions, and to note some of the ways in which we generate selves. Being aware of the mind's activities in the fractions of a second after new situations arise can have the practical consequence of offering some new options for our behavior. Questioning our common-sense perceptions of reality can also create a feeling of strangeness. Brain mechanisms are not guaranteed to feel familiar, warm, and cuddly. The objective reality we assume to be outside ourselves depends on our particular processes of perceiving it.

 

We begin with some background information in Chapter 1, Thinking About Thinking, which defines some terms and considers how a biological explanation of mind and consciousness might be approached. It is a necessary background for the four main parts of the book. Part I, Evolving Mind, is a description of our evolutionary history, starting with the Big Bang that created the universe and culminated in minds that can write and read a page like this one. Chapter 2, Origins of Mind, is an overview of the path from the appearance of the first simple behaviors of bacteria to the complex routines of our own brains, discussing the possible origins of such phenomena as sensations, perceptions, and emotions. It also offers a simple description of some of the basic processes that underlie organic evolution. Chapter 3, Structures of Mind, describes how our modern human minds encapsulate a series of more primitive minds and brains that arose during vertebrate evolution. It provides an introduction to brain structures and some modern techniques used to study the brain. Chapter 4, Primate Mind, begins with a brief general discussion of the minds of animals and then focuses on the primate line from which we are derived, examining similarities and differences between our minds and those of monkeys and apes. Chapter 5, Hominid Mind, discusses stages in the evolution of intelligence in early hominids, the origins of language, and the emergence of modern humans. We consider some of the arguments that there is a universal evolved human psychology: that in many of our reproductive and social behaviors, we appear to express unconscious psychological mechanisms that evolved to meet conditions of a vanished time hundreds of thousands of years ago, long before the invention of agriculture and cities, when humans existed as bands of hunter-gatherers.

 

Part II, Developing Mind, describes how the templates set by our evolutionary history engage an ongoing interaction with the actual physical and cultural environment we face to generate the structures and modules of our modern minds and selves. Chapter 6, Plastic Mind, gives a brief outline of the development of our brains and discusses the plasticity in this process that evolved to permit us to adapt to novel or unpredictable environments. This plasticity is maintained to some extent in our adult brains, and it underlies both the learning of new skills and facts and the ability to recover from brain injuries. Our brains can actually rewire themselves when we learn new manual skills or learn to discriminate some sensory input in a more detailed way. Far from being locked in, as was thought until only a few years ago, many nerve connections in our brains are constantly shuffling about, testing what works best. Chapter 7, Minds and Selves, discusses the development and construction of our human selves. This process requires elaborate feats of learning and memory and draws on mechanisms that are a continuation of those that were active during the early development of the brain. We look at stages in human development and then consider interesting clues to the nature of a self that are obtained from studies on genetics, abnormal development, and patients with brain lesions. Nothing escapes the nudging of our genes. They set the limits on our repertoires of development and behavior. This is not to say we are their prisoners, but rather that we should appreciate how our options have been shaped by them.

 

Part III of the book, ""Society of Mind, takes a plunge into thinking about the many mind, brain, and body modules that underlie our perceptions and actions in the world---modules that form as a consequence of our evolutionary and individual developmental histories. Chapter 8, Perceiving Mind, offers a brief description of how our brains automatically filter and select, through processes of which we are largely unconscious, what fraction of the mass of incoming sensory information impinging on us is relevant for awareness. We frequently see in the external world what our previous experience leads us to expect to see, not what is really there. This is contrary to our common-sense notion that we see a world out there as it is, objectively. After a brief review of some characteristics of our sensing and perceiving, we shift our focus to visual competence. Studies on the visual brains of cats, monkeys, and humans have yielded fascinating insights into what visual consciousness is and where it resides. Chapter 9, Acting Mind, emphasizes the perspective that the most fundamental role of a biological mind is to move a biological body, and to do so quickly if danger is nearby. Mind and brain need to be defined in a way that considers the whole body and its ongoing reciprocal interactions with its world. This chapter offers a brief description of some of the brain structures involved in movement control and also considers models for movement control.

 

In Chapter 10 of Part III, Emotional Mind, we continue a discussion, begun in Chapter 2, of emotions as evolutionary adaptations, and then we review modern experiments that suggest that our emotional minds are the foundation of our rational minds. The cathedrals of our intellect are infused by the inborn emotional wiring of our reptilian brainstem. It is much better to be informed of the ways in which our reason can be distorted as well as enhanced by our emotions than to imagine that we can always face the problems of the world in an objective way. Brain pathways that process emotional responses are more rapid than those that underlie reasoned ones, and some simple exercises will permit you to experience this distinction for yourself. The chapter ends with a topic of contemporary significance for most of us: how emotions that evolved as adaptations to our ancestral conditions can easily be misapplied to our modern circumstances, leading to debilitating stress and disease. Chapter 11, Linguistic Mind, continues discussions begun in Chapter 5, on the evolutionary origins of language, and in Chapter 7, on the development of language, to review evidence that underlying brain mechanisms support the language competence that we have evolved. This leads to the formation of localized modules in the brain that specialize in different aspects of language comprehension and generation. The location of some of these modules is revealed by brain lesions and also by imaging the activity of the brain during language performance.

 

Part IV of the book, Modern Mind, draws together a number of threads that run through the book to summarize our current understanding of the selves generated by our brains---selves generated just as automatically as a bird builds a nest or a beaver builds a dam. Chapter 12,Conscious Mind, looks from several different angles at the consciousness we construct. Ingenious experiments of cognitive psychology reveal agents of our minds that reorder time and space, and suggest that our perceptions and actions can be modeled as the result of an ongoing competition between alternative outcomes. This chapter makes the point that there is no central place in the brain where "it all comes together" and mentions some classical debates on whether the problem of consciousness can be solved. There isn't any "I" inside our heads, at least in the way we commonly suppose. Societies of neuronal agents carry out chores in a way that is more analogous to the performance of a chamber music group than to an orchestra with a central conductor. Further insight into the nature of our consciousness comes from studies on its altered states, as during sleep. We are left with the clear message that our conscious awareness is a very, very small fraction of what is going on in our brains---that most of the activity in our heads is being carried out by another "creature" largely inaccessible to our introspection, as alien to us as occupation by an extraterrestrial interloper.

 

Chapter 13, Theoretic Mind, brings the evolutionary story to the present by first considering the emergence of the human mind that is the basis of the explosion of human activity and culture in the past 4000 years. This is the mind that has generated external forms of symbol storage, such paraphernalia of our modern lives as the books and electronic media that account for much of what is in our heads. We all have modern minds coexisting with emotional and psychological machinery that evolved to meet the conditions of the Paleolithic era, and such machinery frequently is poorly suited to the conditions of modern industrial societies. The modern rational and individualistic self that many of us take for granted is a relatively recent phenomenon. Over most of human history, a more collective identity prevailed. But now, more than ever before, we are not just an unconscious part of organic evolution, but consciously and actively direct it. Does our knowledge of the mind and the past give us a crystal ball for predicting the future evolution of mind? The answer is no, but what we have learned does suggest some appropriate mental tools and attitudes for approaching an understanding of the evolution of evolution, or how change changes itself.

 

There is, in our efforts to understand how our human minds work, an urgency that derives from more than just our natural curiosity, for on its present course the human mind may be driving itself to extinction. In the last 50 years, the human population has increased more rapidly, and we have learned more about biology, than in all of previous human history. The rate of extinction inflicted on animal and plant species by humans is so great that our grandchildren may know only half the plant and animal species we see today. It is as though we all shared a secret, unspoken plan to go on consuming the world until there is no more left. If more people took to heart the material we will be considering---which illustrates the relativity of our mental processes and cultural styles, how intimately we are bound to our environment, and how many of our behaviors are adaptations to a long vanished past---perhaps we might be less intrusive on each other and on the environment. If we hope to shape our future in an intelligent way, we must understand both the evolutionary past that shaped our current behavioral repertoire and the details of how that repertoire is played out in the present.

 

Acknowledgments

 

I would like to acknowledge the early encouragement given to this book project by Owen Flanagan, Daniel Dennett, and Stephen Kosslyn. Marlin, Helen, Jonathan, and Sarah Bownds, and my partner Len Walker, have provided crucial family support. Several reviewers have provided invaluable comments, and I am indebted in particular to my colleague A.O.W Stretton for his close and critical reading of the manuscript. Several students, Cosma Shalizi, Deana Sasaki and Jean Hetzel, have provided crucial assistance with editing, and glossary and manuscript preparation. Finally, I have thoroughly enjoyed interactions with publisher Patrick Fitzgerald, developmental editor Amy Marks, and production editor Susan Graham..

Chapter 1: Thinking About Thinking

 

This is a book about the biology of mind, and it is very tempting just to get on with the evolutionary story outlined in the first section of the book. However, before we can do this, it is necessary both to discuss some definitions of mind and consciousness and to ask how we might approach a scientific understanding of them. Before we can study whether or how the operations going on in our brain might explain consciousness, we have to begin to attempt a description of what it is that we are trying to explain. We must do some "thinking about thinking."

 

How Do We Define Mind and Consciousness?

 

One of the problems we face is that sometimes there seem to be as many definitions of words such as "mind" and "consciousness" as there are people using them. Each of these words refers not to a single entity, but rather to an array of phenomena. Webster's dictionary gives more than five definitions of the word "mind." These definitions are offered mainly with reference to humans. We need to consider also that other animal species besides ourselves have their own distinctive versions of mind.

 

Let's begin by thinking about experiences that we all share. You probably can remember moments of daydreaming or being lost in thought while driving a car and then noting with a start that you have been completely unaware of traveling the past several blocks. During all of this time, your brain was still processing all the relevant information, directing steering, watching the road. An unexpected occurrence, like a child running into the road, would have immediately snapped your attention back to your driving. As another example, you can probably recall an occasion when you have focused on the verbal content of a discussion with someone and have realized only after some time that you have become annoyed, an emotional reaction that grew out of your awareness as your body reacted to signals sent by the other person's posture and tone of voice. Such simple experiences tell us that much more is usually going on than we choose to be aware of.

 

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DESIGN NOTE: IMPORTANT POINT

Our consciousness can include much more than we are aware of at a given moment.

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Awareness

 

What we are aware of does not necessarily depend on its importance to us. We can be aware of trivial things and unaware of very important things. Reading these words might be most important to you right now, but you might also be partially aware of many things not relevant to this task---perhaps the sound of machinery in the next room, or your leg rubbing against the side of your chair. By the same token, you might be able to remember an occasion when you were walking down the street taking in random sights and smells and were unaware, until after the fact, of something very important: that you quickly dodged to the side after a shadow suddenly appeared in your path that might have been caused by a falling object.

 

In such cases we can, if we choose, switch the focus of our attention to what we have not been aware of. Underlying what we can be aware of, however, are many unconscious or implicit operations that may not be accessible to our introspection. These can occur, for example, in the fraction of a second just after we encounter new sensory stimuli. Current inputs are matched with past experiences of similar events to generate our perceptions. These unconscious processes can sometimes make mistakes that fool us. This happens in a well-known experiment in which subjects are shown a brief view of an impossible playing card such as a red ace of spades. Many report seeing what their experience leads them to expect, either a black ace of spades or a red ace of hearts. The brain has edited the actual stimulus and reported something else. You may also have experienced another kind of biasing when, on meeting someone, you immediately liked or disliked that person, for no obvious reason. Perhaps the individual resembled someone from your past, who was loved or feared? Emotional memories can act as filters to give a slight positive or negative "spin" to encounters in the present.

 

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DESIGN NOTE: IMPORTANT POINT

We can be oblivious to unconscious or implicit mechanisms that bias our conscious awareness.

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Thus our current focus of awareness is just a part of our consciousness, which in turn is a small fraction of the vast number of implicit or unconscious operations going on in our brains. Our minds are something larger than our consciousness, and they involve operations that extend beyond our brains. These brains are constantly involved in an array of interactions with other parts of our nervous systems: the spinal cord and autonomic nervous system, as well as muscular, endocrine, and immune systems. This whole ensemble is what carries out actions upon and within the physical and social environment to which we humans have adapted. We can change this environment, and this environment can change our minds. The fact that our minds exist in the context of such complex interactions makes it difficult to offer a precise definition of their boundaries. 1 Probing these relationships is one of the goals of this book.

 

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DESIGN NOTE: IMPORTANT POINT

The nature and the bounds of our minds are quite fuzzy. A neat boundary between the thinker and the thinker's world doesn't exist.

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Think of your stream of conscious awareness from moment to moment. Does it always feel the same? Although our awareness seems smooth and continuous, you will probably agree that it can be of several different kinds, and also built in stages of increasing complexity. To start at the more simple ends of things, you probably have experienced some quiet moments during which your mind felt quite empty, or blank. The simplest notion of awareness is one that is devoid of the content of specific sensing and acting---the state of "just being" that is described by mystical traditions and meditators. At a next level, we all are familiar with various phenomenal states of awareness, such as what it is like to taste an orange or what it is like to feel pain when your forearm is pinched. This is what we mean by having sensations: a simple, direct, and unreflective experience. Behavior experiments raise the possibility that animals and human babies might have such phenomenally conscious states without any concept of a self.

 

Introspection and Reflection

 

A next stage is being "conscious of" our feelings and thoughts, having introspective or reflective access to them. At this point we become selves, the "I" observing ourselves, and can do things like think about how it feels to taste an orange. A further twist is that our conscious awareness can be intentional: related to an object, action, or goal in the outside world. These latter forms of consciousness are clearly observed in higher primates as well as humans. However, talking to ourselves in our heads and talking to others---the narrative self consciousness based on grammatical language---seems to be unique to our human species.

 

The stages listed here are crudely drawn, and professional philosophers and psychologists would wish to make further functional distinctions. Their efforts to define the functional correlates of these and other phenomenal states of consciousness are very important, because we can't hope to address effectively the nerve activities in the brain that correlate with consciousness unless we have described what they are supposed to be doing.

 

How Does Consciousness Emerge from a Brain/Body

 

How do we set about explaining our conscious experience? How do we connect our two different worlds, the inner one of our subjective experience---how we feel, our emotions, what it is like to be somebody---and the objective world "out there" of objects that obey lawful relationships? The book you are holding is "out there"; your experience of it is "what is happening to me." Any complete description of mind or consciousness has to unify these into one whole and describe how they depend on one another. We don't yet know how to relate our subjective experiences to what our brains and bodies are doing, even though most practicing neuroscientists take it as an article of faith that we someday will. This current lack of understanding is generally called the explanatory gap, and it is the subject of intense debate and speculation among philosophers and scientists.

 

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DESIGN NOTE: SELF-EXPERIMENT

The issue of an explanatory gap can be posed with a simple exercise: Take a moment to pinch your forearm gently. Take time to notice how it feels. Now increase the pressure until you just begin to feel pain. At a distinct time and place, you have just had a subjective feeling of mild pain that goes with a particular emotional tone. Now suppose that during this experiment, some super-neuroscientist with access to the interior of your head had measured and accounted for all the nerve messages that occurred during your experience. How much would this explain?

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Defining the Problem

 

Some in the field of consciousness studies insist on making a distinction between the "easy" problem and the "hard" problem of consciousness. The easy problem is said to be explaining the neural basis of things like attention, memory, and sensory motor coordination. These people say that no matter how much neuroscientists discover about these things, it won't crack the hard problem: They still won't be able to tell us why we experience the color and smell of a rose as we do. Third-person science will never get us to first-person experiences. There has to be something else, some really radical solution beyond the province of conventional psychology and neuroscience.

 

One response to this position, however, is to argue that the objective and the subjective refer to different ways of knowing rather than different bodies of knowledge. Why should translating between them be required for theories of consciousness? If we are materialists who take mind to be based on matter, any theories of consciousness must blend with neurobiological and psychological theories and descriptions. 2 The hard problem, then, is being addressed by current experiments that are revealing neural correlates of conscious subjective experiences such as vision, attention, and memory. The really hard problem is to find a unified or integrated description of all of these. (Approaches to this problem are the subject of Chapter 12.) Once we have assembled enough of the pieces, the supposedly hard problem of consciousness may evaporate, just as the concept of phlogiston disappeared when the true nature of fire was illuminated, the mystery of light yielded to the discovery of electromagnetic waves, and the mystery of life (how each organism replicates itself) was clarified by the discovery of DNA.

 

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DESIGN NOTE: IMPORTANT POINT

The debate over the "easy" versus the "hard" problems of consciousness remains to be resolved.

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This argument takes the view that there are no questions concerning the physical basis of consciousness that differ in principle from other ordinary problems about the physical and functional basis of genes, inheritance, or solidity and liquidity. However, it is also possible that at this point, we could be in the position of a person ignorant of relativity theory who is informed that matter is a form of energy but does not understand the physical concepts that link quantum phenomena to matter and energy alike. Future theory might provide the scientific concepts we need to close the explanatory gap.

 

Problems with Words

Note: this section was not included in published book

 

As we get into the thicket of thinking about minds, consciousness, and brains, we bump into some major quandaries in dealing with our language. I frequently find myself thinking: "I know what I mean, or feel, but I just can't put it into words." As an example, the French translation of the title of an article "What is it like to be a bat." must be rendered as "What effect (or impression) does it make to be a bat." 3 French speakers surely have the concept of "what it is like to be...." but no clear, concise expression for it. Different cultures develop different systems of description. An opposite problem occurs when a word or phrase seems to represent something but in fact does not. A well known example is " phlogiston", coined in the eighteenth century to refer to the hypothetical material with negative mass that was supposed to be released from burning bodies. Other examples are "elan vital", "animal magnetism" and "telepathy". So, there can be a double jeopardy, words playing hard to get or easy to get and meaning nothing. Language also is made ambiguous by the existence of multiple belief systems that use the same words in different ways, so that language and thought have to be studied the same way that ecologists study multi-species communities. 4

Imposing words are used in talking about mind: concept, attribution, intention, affect, representation, strategy, consciousness, cognition, phenomenology. The traditions of ethology, psychology, philosophy and cognitive science differ over how to use these mental terms. I am going to proceed as simply as possible, adopting an evolutionary and ecological perspective, noting what animals and humans do in their natural habitats, and then asking what sorts of underlying mental operations might account for this behavior. One mental operation that can bias our insights, frequently outside our awareness, is the use of metaphors (words for one object or idea being used for another to suggest a similarity between them, but without an explicit comparison). In our common sense, or folk, psychology we often describe our mental states and processes using metaphors. Someone saying to you "I don't want to put ideas in your head" is taking mind to be a container. If you say "Part of me doesn't want to do that" you are using the metaphor of mind parts as persons. "John saw that Jim could not be trusted" is making believing like seeing. This sort of process is pervasive in our lives. As another example, consider how the fundamental physical verticality schema of up and down - relevant to any animal moving against gravity - is usually metaphorically projected to a whole array of oppositions: happy is up, sad is down; health is up, sickness is down, rational is up, emotional is down. 5

 

Assembling an Explanation

 

How, then, do we set about assembling an explanation for anything as complicated as our consciousness? We might start with some design principles that we know something about. We know that our bodies are hierarchical systems built up from smaller subunits and components, as shown in Figure 1-1. The ultimate particles of atomic physics make up our atoms and molecules. Our molecules then organize themselves into cells. Systems of nerve cells form our nervous systems and brains. The entities at each level are building blocks of those at the next level. The description can be expanded beyond our individual selves, as our minds become components of the larger entities of societies and cultures. Each level of this hierarchy has its own laws and theories, which armies of academic specialists study. 6

 

 

 

Figure 1-1

A hierarchy diagram depicting how complicated structures are built up from simpler ones.

 

This book takes the tack of sidestepping, or bypassing, the issue of relating our brain operations to our subjective feelings (bridging the explanatory gap mentioned above), and suggests instead, as indicated by the solid arrows to the left of the dashed ones in Figure 1-1, that mind is what brain/body does---in the same sense that digesting our food is what the gut does. We can trace up through the lower levels in the hierarchy to observe that in practice, each level of organization, built up of simpler ones, has its own laws and that its members in turn serve as the building blocks for the next level of organization. We then ask what rules are working at this next level, what new operating environment we are in.

 

We tend to visualize the assembly of our component molecules into cells, of our cells into tissues, and so on as being like working with building blocks or a simple erector set where things come together in an intuitive, linear fashion. 7 This can be a misleading vision, for in fact, all complex entities, whether organisms or thunderstorms, are nonlinear systems. They emerge from their simpler components in a way that cannot be predicted by merely summing their components. Examples of nonlinear processes include schools of fish and flocks of birds, whose grouping is aided by attractive energies arising because the surrounding fluid moves with them, and groups of lipid molecules that organize themselves into a biological membrane by minimizing the repulsive forces between lipid chains and water molecules. 8

 

We might view consciousness as a higher-level or emergent property of the brain in the simple sense that solidity is an emergent property of water molecules when they are in a lattice at low temperatures. In this view, consciousness might be taken as a physical property of the processes of the brain in the same sense in which solidity is a property of the molecules in an oak table or an icicle. The perspective that brain processes cause consciousness, but also that consciousness is a feature of the brain, avoids both the extreme of making mind separate from body and the excessively reductive materialistic view that mind is "nothing but" a group of molecules organized into nerve cells. In our present state of knowledge we can observe, in the brain, neuronal activity that correlates with, but does not explain, consciousness. We eventually hope to have a causal theory that explains why consciousness and neuronal activities are correlated, just as we now have causal theories that explain why the solidity of a substance correlates with its molecular structure, or why thunder and lighting are correlated during a storm.

 

*********

DESIGN NOTE: IMPORTANT POINT

We can think of our "mindstuff" as different from our "nervestuff" without edging back toward a dualism that separates body and mind, because we are talking about the same kind of distinction we make when we say that DNA is different from the elementary particles of atomic physics of which it is ultimately composed.

*********

 

It is important to avoid some potential confusion about explanations. We appreciate that more complex entities can be explained in terms of simpler components. Knowing what we do about nerve cells, we can see how the laws governing a nerve signal follow from the laws of chemistry and electricity, and in this sense we can "reduce" it to them. But this is a very peculiar relationship. Under other conditions, the same laws of chemistry and physics explain liquid crystal displays of wrist watches, clouds forming over the ocean, thunder and lightning, and sugar dissolving in our coffee. Those laws of chemistry and physics in turn follow from the laws of quantum mechanics, which the physicists call fundamental, but only under the conditions where we normally find matter. Quantum mechanics has very different consequences in particle accelerators ("atom smashers") and at the edges of black holes than it does in your kitchen. To propose a genuine explanation, we must be armed with knowledge of both the lower-level laws and the conditions under which they act. Those conditions are so variable that we could never hope to have the higher-level laws just "fall out" (as the physicists say) of the quantum equations. If we were to restart the universe, would everything happen in just the same way? Perhaps there would eventually be clouds and quartz crystals, but what about mushrooms and animals with nerve cells and action potentials---and, in particular, us, puzzling over consciousness? These are not all entities whose appearance anyone could have predicted just from the equations of quantum mechanics: There are simply too many different ways in which things could have been fit together by evolution.

 

Figure 1-1 shows arrows pointing in both the upward and downward directions. The up arrows indicate simpler things coming together to make more complicated things, such as lipid molecules making cell membranes or the organ systems of our bodies constructing a skin or epidermis that encloses us. The downward arrows show that emergent entities can constrain and direct the components that built them up. A cell membrane is a physical compartment, or bag, that contains and exerts some control over all of its smaller components, just as on a larger scale our skins establish the context for what our muscles and other tissues can do. By the same token, if a whole organism constrains and regulates its component tissues, it should not surprise us that an emergent property like our subjective consciousness can organize, monitor, or direct the nerve assemblies of which it is constructed. And as we will see in later chapters, there is good evidence that this really happens. There doesn't have to be anything mystical about it. Our self conscious behavior can affect and shape the nerve and muscle physiology in our bodies. 9 Finally, the consciousness or mind that each of us experiences is not the final step in the causal chain, for it is strongly influenced and organized by the particular human culture in which we grew up.

 

Organism and Environment

 




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