Consciousness: A Very Short Introduction PDF

# Consciousness: A Very Short Introduction ## Susan Blackmore ### Second Edition #### Contents - List of Illustrations - 1 Why the Mystery? - 2 The Human Brain - 3 Time and Space - 4 A Grand Illusion - 5 The Self - 6 Conscious Will - 7 Altered States of Consciousness - 8 The Evolution of Conscious...

# Consciousness: A Very Short Introduction ## Susan Blackmore ### Second Edition #### Contents - List of Illustrations - 1 Why the Mystery? - 2 The Human Brain - 3 Time and Space - 4 A Grand Illusion - 5 The Self - 6 Conscious Will - 7 Altered States of Consciousness - 8 The Evolution of Consciousness - Further Reading - Index #### List of Illustrations - The Great Chasm - Descartes' Theory of Reflexes - The Philosopher's Zombie - The Cartesian Theatre - A Necker Cube - Hemifield Neglect - Two Visual Streams - Blindsight - The Cutaneous Rabbit - The Spotlight of Attention - Global Workspace Theory - A Visual Illusion - Finding the Blind Spot - Change Blindness - Split Brain Experiment - The Teletransporter - Brain Areas Involved in Volition - Libet's Experiment on Deliberate Action - The Illusion of Conscious Will - The Old Hag - The Right Temporo-Parietal Junction - Mapping States of Consciousness - What is it Like to be a Bat? - Chimp and Mirror - Looking in the Fridge #### Chapter 1: Why the Mystery? **The 'Hard Problem'** What is consciousness? This may sound like a simple question, but it is not. Consciousness is at once the most obvious and the most difficult thing we can investigate. We seem either to have to use consciousness to investigate itself, which is a slightly weird idea, or to have to extricate ourselves from the very thing we want to study. No wonder philosophers have struggled for millennia with the concept; and for long periods scientists refused even to study it. The good news is that, in the 21st century, 'consciousness studies' is thriving. Psychology, biology, and neuroscience have reached the point where they are ready to confront some tricky questions: What does consciousness do? Could we have evolved without it? Is consciousness an illusion? What do we mean by consciousness, anyway? This does not mean that the mystery has gone away. Indeed, it is as deep as ever. The difference now is that we know enough about the brain to confront the problem head on. How on earth can the electrical firing of millions of tiny brain cells produce this - my private, subjective, conscious experience? **Defining Consciousness** There is no generally agreed definition of consciousness, but the following are ways often used to talk about it. - **'What it's like to be...':** If there is something it is like to be for an animal (or computer; or baby) then that animal (or computer; or baby) is conscious. Otherwise it is not. - **Subjectivity or Phenomenality:** Consciousness means subjective experience or phenomenal experience. This is the way things seem to me, as opposed to how they are objectively. - **Qualia:** (singular: quale, pronounced qua-lay): The ineffable subjective qualities of experience, such as the redness of red or the indescribable smell of turpentine. Some philosophers claim that qualia do not exist. - **The Hard Problem:** How do subjective experiences arise from objective brains? **The Theatre of the Mind** The most natural way to think about consciousness is probably something like this. The mind is like a private theatre inside my head, where I sit looking out through my eyes. But this is a multi-sensational theatre with touches, smells, sounds, and emotions. And I can use my imagination to conjure up sights and sounds as though seen on a mental screen or heard by my inner ear. All these thoughts and impressions are the 'contents of my consciousness' and 'I' am the audience of one who experiences them. This theatre imagery fits happily with another common image of consciousness - that it flows like a river or stream. In the 19th century, the 'father of modern psychology', William James, coined the phrase 'the stream of consciousness' and it seems apt enough. Our conscious life really does feel like a flowing stream of sights, sounds, smells, touches, thoughts, emotions, worries, and joys - all of which happen, one after another, to me. This way of conceiving of our own minds is so easy, so natural, that it hardly seems worth questioning. Yet when we get into an intellectual muddle, as we have with the problem of consciousness, it may be worth challenging some basic assumptions - in this case, these apparently innocent analogies. The strongest challenge comes from Dennett who argues that while most people are happy to reject Cartesian dualism, they still retain dualist thinking in imagining what he calls the Cartesian theatre. This is not just the analogy of the mind with a theatre, but the notion that somewhere in the mind or brain there must be a place and time at which everything comes together and 'consciousness happens'; or a finishing line in the brain's activities, after which things mysteriously become conscious or 'enter consciousness'. This has to be false, claims Dennett, because the brain is a parallel, distributed processing system with no central headquarters and no place in which 'I' could sit, making decisions and watching the show as things pass through my consciousness. Instead, the many different parts and processes of the brain just get on with their own jobs, communicating with each other when necessary, and with no central control. What, then, could correspond to the theatre of consciousness? Somehow we have to understand how this feeling of being a conscious self who is having a stream of experiences comes about in a brain that really has no inner theatre, no show, and no audience. #### Chapter 2: The Human Brain **A Big Brain** Said to be the most complex object in the known universe, a human brain, at nearly 1.5 kg or 3 lbs, is about three times larger than it should be by comparison with our closest relatives, the other great apes. It contains about 100 billion neurons (i.e. nerve cells) connected by trillions of synapses, as well as billions of supporting glial cells and blood vessels. The brain and spinal cord together make up the central nervous system, the spinal cord being connected to the brain stem and then midbrain which is responsible, among other things, for controlling the sleep-wake cycle. Behind this lies the cerebellum, or 'little brain', mostly concerned with fine movement control, and above it is the latest part of the brain to evolve, the cerebral cortex (i.e. the outer layer of the brain). This is the part that shows the greatest differences from other species and is divided into four lobes, occipital at the back, temporal above the ears, parietal at the top, and frontal, of course, at the front.