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The Secrets of Consciousness
By Scientific American
Scientific AmericanCopyright © 2013 Scientific American
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The Nature of Consciousness
How Unconscious Mechanisms Affect Thought
by Christof Koch
What is consciousness? What is this ineffable, subjective stuff — this thing, substance, process, energy, soul, whatever — that you experience as the sounds and sights of life, as pain or as pleasure, as anger or as the nagging feeling at the back of your head that maybe you're not meant for this job after all. The question of the nature of consciousness is at the heart of the ancient mind- body problem. How does subjective consciousness relate to the objective universe, to matter and energy?
Consciousness is the only way we experience the world. Without it, you would be like a sleepwalker in a deep, dreamless sleep, acting in the world, speaking, having babies, but without feeling anything. You would feel nothing, nada, nichts, rien. Indeed, in the most famous deduction of Western thought, philosopher and mathematician René Descartes concluded that because he was conscious he existed. That was his only unassailable proof that he wasn't just a chimera. Maybe he didn't have the body he thought he had, maybe he had fake memories (premonitions of The Matrix), but because he was conscious he must exist.
Yet the questions go on. Are only people conscious? What about a fetus? What about a neurological patient in a persistent vegetative state, such as Terri Schiavo (who died in 2005), who can't do much more than open and close her eyes? Although many are willing to accord sentience, consciousness, to our beloved cats and dogs, what about apes, monkeys, whales, mice, bees and all the other critters on the planet? Can a fly be conscious? What about artificial consciousness? Is your cool iPhone sentient? Can machines ever become conscious, as is widely assumed in so many science-fiction novels and movies?
Until recently, these questions were purely within the domain of speculative philosophy and fantasy. But over the past decades, science has been making huge strides in exploring the brain. An immense number of psychological, medical, neurobiological and physical stories about consciousness can now be told.
I am a scientist who seeks rational explanations of ineffable consciousness and of how and why it arises in the brain. But I also realize that our universe is a strange place; there are more things in heaven and earth than are dreamt of in philosophy. So I try to be humble when it comes to one of the most mystifying aspects of this universe — that I wake up each day and find myself conscious, capable of seeing, touching, loving, feeling and remembering. I am not a zombie! Many different traditions besides the modern scientific one have provided answers, and we should not reject them out of hand but listen to them.
As I wrote these lines, I was flying back from the 2008 annual meeting of the Association for the Scientific Study of Consciousness that took place in Taipei, Taiwan. It's a gathering of hard-nosed philosophers, neurologists, psychologists and neuroscientists concerned with consciousness. One of its high points is an annual award, named in honor of the father of American psychology. The 2008 William James Prize for Contributions to the Study of Consciousness went to Naotsugu Tsuchiya, a young neurobiologist from the California Institute of Technology. What had he done that caught the attention of the prize committee?
In 2005 Tsuchiya invented a technique, continuous flash suppression, which renders a picture invisible, hiding it from your conscious sight. Yet some part of your brain has access to the image and influences your behavior in untold ways. The way it works is simple. Say Tsuchiya wants to camouflage a picture of an angry male face. With the help of a split computer screen, Tsuchiya projects a faint image of this snarling guy into your left eye. Your right eye sees a rapidly changing set of colored rectangles, one on top of another. If you keep both eyes open, all you see are the ever changing series of colored patches but no angry face. The constantly flickering colors attract your attention in a way that the static portrait does not. As soon as you close your right eye, the face becomes visible. But otherwise you have no inkling that the face is there, even though your left eye has been staring at it for many minutes. You simply do not see it. So what is the big deal?
Functional brain imaging shows that this angry face still activates a part of your brain that is concerned with fear, the amygdala. That is, at least some sector of your brain knows about the face — as it ought to because an angry male face in front of you might spell big trouble. This brain activity remains unconscious but may influence your behavior or generate a subtle feeling of unease.
Using this technique, psychologist Sheng He, with his student Yi Jiang and their colleagues at the University of Minnesota, made an intriguing discovery. They projected to one eye a photograph of a naked person on one side of the gaze and a scrambled version of the same image on the other side. They then hid both using continuous flash suppression. The paid volunteers who participated in the experiment never saw anything but flashes of color. The psychologists asked the volunteers to guess whether the naked person was in the left or the right part of the image. But they couldn't. Their guesses were no better than chance.
He and Jiang demonstrated that the observers attended to the naked picture but not to its scrambled counterpart. Even more interesting, straight males attended to pictures of naked women but were slightly repelled by pictures of naked men. Straight women were attracted to pictures of naked men without showing a consistent repulsion for pictures of naked women. Gay men behaved much like straight women; they unconsciously paid attention to the pictures of the naked men but not to those of women. What is disconcerting about this experiment is that this all took place outside the pale of consciousness. Because the observers never actually saw the naked images, they had no idea they were attracted or repelled by them. This experiment is scary because it seems as if people's sexual orientation could be inferred (statistically) from their unconscious attentional biases. An example of the unconscious mind at work. Freud would have loved it.
What this experiment teaches us is that the mind has many nooks and crannies; some — probably the minority — are consciously accessible, whereas most are hidden from introspection, lost in the vast catacombs of the brain. Yet they can powerfully influence your behavior, making you do things without knowing why. Continuous flash suppression — and other techniques that magicians and psychologists have invented to distract you so you do not see things while looking at them — in combination with functional brain imaging is a delicate tool to map the landscape of the visual unconscious.
--Originally published: Scientific American Mind 19(5), 18-19. (October/November 2008)
Exploring the "Mind" of Bees by Christof Koch
We take the magical gift of consciousness for granted. From the time I awaken until I fall into a deep, dreamless sleep, I am flooded with conscious sensations. And contrary to assertions made by philosophers, novelists and other literati, by and large this stream of consciousness does not relate to quiet self-reflection and introspective thoughts. No, most of it is filled with raw sensations.
In 2008, a friend and I climbed a sea cliff above the Pacific surf at Malibu, Calif. When I am on the sharp end of the rope, my inner critic — that voice in my head reminding me of deadlines, worries and my inadequacies — is gone, is silent. My mind is all out there — conscious of the exact orientation, shape and texture of the rock, looking for tiny indentations where I can get purchase for my fingers and toes, always aware of how high I am above the last bolt. One moment I am exquisitely aware of my feet on all too smooth rock, reaching upward with my left hand for a handhold. The next I am airborne, my right hand bloody, my right rib cage aching. After catching my breath and shouting to my anxious belayer that I'm okay, I am filled with adrenaline for having survived yet another fall, can't contain my enthusiasm, and scream.
Two weeks later, only a bruised rib remained as a testament to how much of the stream of consciousness is pure sensation. Whether you are weaving on a motorbike through flowing traffic, running in the mountains, dancing to fast rock and roll, reading an engaging book, making love or debating with your friend, your eyes, ears, skin and body sensors paint an engrossing picture of the outside, including your own body, onto your mind's canvas.
I suspect this feeling is not that dissimilar to the way animals consciously experience their world. Except perhaps for the great apes and a few other privileged big-brained animals, most species do not posses the highly developed sense of self, the ability to reflect on oneself, that people have. Most biologists and pet owners are willing to grant consciousness to cats, dogs and other mammals. Yet our intuitions fail us completely when we consider fish and birds, let alone invertebrates such as squid, flies or worms. Do they experience the sights and sounds, the pains and pleasures, of life? Surely they can't be conscious — they look too different from us, too alien.
Insects, in particular, were long thought to be simple, reflexive creatures with hardwired instinctual behaviors. No more. Consider the amazing capabilities of the honeybee, Apis mellifera.
Martin Giurfa of the University of Toulouse in France and Mandyam Srinivasan and Shaowu Zhang, both at the Australian National University in Canberra, trained free-flying bees, using sugar water as a reward, in a variety of complex learning tasks. The neuroethologists taught the bees to fly in and out of tall cylinders with one entryway and two exit holes. Each bee had to choose one of two exits to leave the cylinder and to continue her flight. (In bee colonies, males are a small minority and do only one thing — and that only during the virginal flight of the colony's queen.)
These cylinders were staggered into mazes with multiple levels of "Y" branch points that the bees encountered before reaching the desired feeder station. In one set of experiments, the scientists trained bees to track a trail of colored marks, as in a scavenger hunt. The bees could then follow — more or less — the same strategy in a completely unfamiliar maze. Amazingly enough, bees can use color in an abstract manner, turning right, for instance, when the branch point is colored blue and left when it is colored green. Individual animals developed quite sophisticated strategies, such as the right-turn rule, that always led to the goal, though not necessarily by the shortest route.
In humans, the short-term storage of symbolic information — as when you enter an acquaintance's phone number into your iPhone's memory — is associated with conscious processing. Can bees remember task-relevant information? The gold standard for evaluating working memory is the delayed matching-to-sample (DMTS) paradigm. The subject looks at a picture for a few seconds. The test image then disappears for five or 10 seconds. Subsequently, two pictures are shown next to each other, and the animal has to choose, by pushing a lever or moving its eyes, which of the two images was the test picture. This test can be carried out correctly only if the animal remembers the image. A more complex version, the delayed nonmatching-to-sample (DNMTS) task, requires one additional processing step: choosing the opposite image from the one previously shown.
Although bees can't be expected to push levers, they can be trained to take either the left or the right exit inside a cylinder modified for the DMTS test. A color disk serves as a cue at the entrance of the maze, so that the bee sees it before entering. Once within the maze, the bee has to choose the arm displaying the color that matches (DMTS) or differs from (DNMTS) the color at the entrance. Bees perform both tasks well. They even generalize to a situation they have never previously encountered. That is, once they've been trained with colors, they "get it" and can now follow a trail of vertical stripes if a disk with vertical gratings is left at the entrance of the maze. These experiments tell us that bees have learned an abstract relation (sameness in DMTS, difference in DNMTS) irrespective of the physical nature of the stimuli. The generalization to novel stimuli can even occur from odors to colors.
Although these experiments do not tell us that bees are conscious, they caution us that we have no principled reason at this point to reject this assertion. Bees are highly adaptive and sophisticated creatures with a bit fewer than one million neurons, which are interconnected in ways that are beyond our current understanding, jammed into less than one cubic millimeter of brain tissue. The neural density in the bee's brain is about 10 times higher than that in a mammalian cerebral cortex, which most of us take to be the pinnacle of evolution on this planet. In humans, widespread loss of cerebral cortex, as in the vegetative patient Terri Schiavo, leads to an irreversible loss of consciousness. That is not to say that a cerebral cortex is necessary for consciousness in creatures with a different evolutionary heritage.
Bees live in highly stratified yet flexible social organizations with group decision-making skills that rival academic, corporate or government committees in efficiency. In spring, when bees swarm, they choose a new hive that needs to satisfy many demands within a couple of days (consider that the next time you go house hunting). They communicate information about the location and quality of food sources using the waggle dance. Bees can fly several kilometers and return to their hive, a remarkable navigational performance. Their brains seem to have incorporated a map of their environment. And a scent blown into the hive can trigger a return to the site where the bee previously encountered this odor. This type of associative memory was famously described by French novelist Marcel Proust in À la Recherche du Temps Perdu.
Given all of this ability, why does almost everybody instinctively reject the idea that bees or other insects might be conscious? The trouble is that bees are so different from us and our ilk that our insights fail us. But just because they are small and live in colonies does not mean that they can't have subjective states, that they can't smell the fragrance of the golden nectar or experience the warm rays of the sun or maybe even have a primitive sense of self. I am not a mystic. I am not arguing for pan-psychism, for the notion that anything is conscious. Nor am I assuming that bees can reason or can reflect on their fate as animated cartoon bees.
What this dilemma highlights is that there is no accepted theory of consciousness, no principled theory that would tell us which systems, organic or artificial, are conscious and why. In the absence of such a theory, we must at the very least remain agnostic about consciousness in these creatures. So the next time a bee hovers above your breakfast toast, attracted by the sweet jam, gently shoo her away. For she might be a fellow sentient being, experiencing her brief interlude in the light, shoehorned between this moment and eternity.
--Originally published: Scientific American Mind 19(6), 18-19. (December 2008/January 2009)
The Quest to Find Consciousness by Gerhard Roth
What is the nature of consciousness? Asking the question is simple, but determining the answer is not. Consciousness can seem utterly familiar, even mundane. People excuse themselves for "unconsciously" ignoring someone at a party or profess that they seek to "expand their consciousness." But a true understanding of the phenomenon remains elusive.
How do the brain's physical systems work together to create the subjective experiences of the mind — the self-reflective, private thoughts that make us who we are? Noting the difficulty of using empirical science to quantify something so subjective, David J. Chalmers, a philosopher at the University of Arizona, has dubbed this the "hard problem."
Excerpted from The Secrets of Consciousness by Scientific American. Copyright © 2013 Scientific American. Excerpted by permission of Scientific American.
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