Cover image for Why we feel : the science of human emotions
Why we feel : the science of human emotions
Johnston, Victor S.
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Publication Information:
Reading, Mass. : Perseus Books, [1999]

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ix, 210 pages : illustrations ; 25 cm.
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Central Library BF511 .J65 1999 Adult Non-Fiction Non-Fiction Area

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Why do we think some people are beautiful? Why do orgasms feel good? Why do we get angry? Anxious? In this intriguing book, biopsychologist Victor Johnston explores the origins of human emotions. Drawing on computer science, neurobiology, and evolutionary psychology, he shows us that emotions are not some strange accident of nature, but are instead the basis of learning and reasoning, and help us to adapt to a complex, rapidly changing environment. In the process, he offers a radical new view of reality: What we see, hear, smell, feel--even what we consider beautiful--is not an accurate representation of the world around us; rather, our feelings are illusions, shaped by millions of years of evolution. In clear and colorful prose, Johnston helps us navigate the intimate relationship between our private conscious feelings and our biological survival--and tells us what this means for human creativity, innovation, and free will.

Reviews 3

Booklist Review

Pushing the Darwinist explanation of the mind, Johnson maintains that our emotions are "evolved adaptive illusions of a conscious mind." Whatever one's opinion of his argument, one can't gainsay the welcome rhetorical clarity of its presentation. Johnson is a psychobiologist who here interweaves his computerized experiments on facial recognition with an interpretation of the evolutionary advantages promoted by the primary emotions of fear, anger, joy, sadness, surprise, and disgust. These are emergent functions of the brain's organization, proposes Johnson, and their evolutionary fitness is shaped by each emotion's hedonic tone (pleasant or unpleasant) and its intensity. Tone and intensity receive the interesting definition of being "amplifications of the ultimate reproductive consequences arising from current . . . social circumstances" --that being one explanation of a person's disappointment over a dateless Saturday night. Johnson mitigates his material view of mind with the practical question of what being human would be like without emotion: quite possibly, impossible. Ably argued, his work is a provocative exploration of the emotional component of the mystery of consciousness. --Gilbert Taylor

Publisher's Weekly Review

The world, according to Johnston, professor of psychobiology at New Mexico State University, is dramatically different from the way in which any of us experience it. In fact, he argues, the world is a dark, silent, tasteless, odorless and colorless place. We create all that we sense: the brilliant color of a sunset, the mouthwatering sweetness of a peach, the acrid odor of rotten eggs. All of our sensual abilities, indeed our ability to feel any emotions, are best envisioned as emergent properties of the neural processes in our brain. Sugar, for example, is neither inherently sweet nor satisfying. Rather, we believe it so because over evolutionary time those most drawn to the energy in sugar were the ones most likely to survive and successfully reproduce. Johnston does an impressive job of explaining how millions of years of evolution are capable of yielding complex behaviors. He demonstrates that computers are capable of learning and developing preferences. Arguing by analogy, he concludes that human reasoning and likes and dislikes are outgrowths of the evolutionary process by which neural networks deal with rapidly changing environments. Johnston concludes his challenging book by discussing the implications this sort of evolutionary worldview has on the concept of free will. (May) (c) Copyright PWxyz, LLC. All rights reserved

Choice Review

Johnston provides the answer to the question "Why do we feel?" Her answer: "Because it is adaptive to do so." But unlike other evolutionary explanations of behavior that may degenerate into "just so" stories, Johnston's perspective provides exceptional insight into why feelings are adaptive and how they may have evolved. The author discusses the use of "dry cognitive science" (DCS) tools (computer simulations, neural network modeling) to demonstrate how emotions likely evolved and why the DCS perspective is inadequate to explain the complexities of emotional experience. An intelligent, thought-provoking discussion of what many people have trouble even defining--the experience of conscious human emotions--the book is thorough in its scope; since the author complements the evolutionary perspective with a physiological one, the book is appropriate for students of evolutionary, social, or biological psychology. In addition, one of the book's particular strengths is Johnston's easy-to-read narrative style; he demonstrates his own thought process and leaves the reader to disagree with particular points without discarding the big picture. Undergraduates, specialists, and general readers. W. F. Sternberg; Haverford College



Chapter One The Grand Illusion WHEN I FIRST MET DAVID, HE WAS SITTING NERVOUSLY on a small wooden chair in a psychiatrist's office. As a psychology student, I spent my summer vacations cleaning the floors of mental hospitals, and this was my very first opportunity to see a real clinical interview. The fourteen-year-old boy was disheveled and fragile, and he never raised his eyes above the level of the large wooden desk that separated him from the discerning eyes of the attentive psychiatrist. "And where are the monsters now?" asked the doctor. The little red-haired boy remained silent, apparently lost in his own thoughts. Then suddenly, as if awakening from a dream, David stood, turned around, and pointed toward the door. "They're in there," he said, probing at a very small black dot that I am sure no one, before that day, had ever noticed. "They're just waiting for you to go."     After the interview I sat patiently as the psychiatrist filled out a voluminous pile of forms, but at the first opportunity I asked, "What do you think?" The reply disturbed me. "Schizophrenia," he asserted. "Early stages. But we'll admit him to the hospital today." "What will happen to him?" I asked, feeling a wave of sadness spread over my body. "Probably spend the rest of his life here," he replied as he checked off more boxes on the papers in front of him. "Lost reality contact!" he continued, as if this would make everything clear to me. But nothing was clear. I wondered what was going on inside David's head. What was it like to experience a different reality?     Plainly David had great difficulty getting along in the world in ways that you and I take for granted. For David, the lurking monsters were his reality. He was as convinced of their existence as I was convinced that they didn't exist. For a moment I wondered what it would be like if the psychiatrist also saw the monsters and I were all alone in my personal reality; the thought frightened me. I had a glimpse of David's condition and could feel his fear. There was no doubt that his mind was disturbed--in fact, some might say that he had lost his mind--but the problem was manifested by his loss of contact with reality. He didn't see or interact with the world in an appropriate way, like the rest of us. It was many years before I gained some insight into the tenuous links between mind and reality, how they are established, and how easily they can be shattered. I also began to realize that even the mentally "well" among us have a distorted picture of the physical world and that this misperception has prevented us from understanding what may be the essence of our humanity: our emotions. Indeed, we are not as different from David as some of us might like to think.     Most of us believe that there is a real world "out there" that we can experience through our senses; we can see it, hear it, touch it, smell it, and taste it. Furthermore, we believe our picture of the world is, for the most part, an accurate reflection of that reality. That is, we believe that a sweet red apple appears red because it really is red, and that it tastes sweet because sweetness is an inherent property of the sugars inside apples. Of course, we also know that sometimes our senses can be deceived. We have all experienced visual illusions. For example, if we stare at a red apple for a few minutes and then quickly look at a white wall, we perceive what appears to be a green apple on the wall. This mental image is clearly an illusion since the apple isn't really there and it's the wrong color. Our prolonged staring at the red apple has depleted the "red" pigment in the visual receptors of a small area of our retina, and the reduced input from these receptors is responsible for the color illusion. If there is a red apple in the physical world and we have a mental image of a red apple, then we believe that our perception of reality is accurate. If, however, our mental image is different from the physical world, then, just like David, we are hallucinating. This commonsense view of the relationship between the physical world and the mental world appears to be very straightforward and reasonable; it is not, however, the viewpoint of most cognitive scientists.     Cognitive scientists are interested in determining how humans acquire, process, retain, and use knowledge as a basis for action or for generating further knowledge. To address these questions, they have used two basic strategies. The first is to build computer models of cognitive processes, like decision making, and then refine them by comparing their performance to the behavior of human subjects under similar conditions. Because of its reliance on computers rather than on real brains, this approach is sometimes referred to as the "dry cognitive science" (DCS) strategy. The second strategy is to study the effects of electrical or chemical stimulation of real brains, examine the impact of brain damage, or record from the brains of individuals engaged in different kinds of information-processing tasks. Because of its reliance on real brain experiments, this approach is often called "wet cognitive science" (WCS). These two different experimental approaches have led to conflicting views on the nature of our mental states and their relationship to the physical world. DRY COGNITIVE SCIENCE Cognitive scientists with a DCS viewpoint often explain the connection between the physical world and the mental world by drawing an analogy between the human brain and a computer. Inside a computer, the different states of the transistors represent pictures or sounds, and a variety of computer programs can act on these stored patterns. This is what occurs when we scan a picture into a computer and then manipulate the image with a program like Adobe Photoshop. Of course, we could also capture the image with a television camera, and more sophisticated programs could recognize objects, letters, or words in the captured image. Indeed, this is exactly what happens inside the "brain" of an intelligent robot.     Drawing on this computer metaphor, it is relatively easy to believe that nerve cells in the brain can play a role similar to that of the transistors in a computer. That is, when the image of a red apple enters our eye, it is immediately converted into a pattern of nerve impulses, and the software programs of our visual system then process this neural pattern. The neural pattern simply represents the attributes of the object in the outside world, while the cognitive processes, like seeing or thinking, are the equivalent of computational procedures that manipulate these symbolic representations.     This computer metaphor is powerful and seductive. Most DCS advocates view the brain as a general-purpose biological computer that can implement a wide variety of software programs. Because the same computer programs can be run on a wide variety of general-purpose machines, such as Macintosh and IBM computers, DCS holds that the actual structure of the brain is of little importance for understanding mental processes. In the parlance of DCS, the brain is equivalent to the hardware of a general-purpose computer, and the processes of the mind, like seeing, thinking, and feeling, are the result of sophisticated programs executed by this hardware. When David Marr proposed computer algorithms for seeing and Noam Chomsky uncovered the universal rules of grammar, it soon became widely accepted that all cognitive processes could be viewed as computational procedures.     In his book How the Mind Works , Steven Pinker states that the environment "gives off patterns of sounds, sights, smells, tastes, and feels that the senses are designed to register." The attributes of the world are represented as symbols, and "a symbol is connected to its referent in the world by our sense organs." Symbols have meaning, according to Pinker, when "the unique pattern of symbol manipulations triggered by the first symbol mirrors the unique pattern of relationships between the referent of the first symbol and the referents of the triggered symbol." In essence Pinker's computational theory of mind rests on the belief that inside the brain there is a world of symbols and symbol interactions that mirrors the external reality, and that the processes of mind, like thinking, "are a kind of computation." From his DCS perspective, "beliefs and desires are information, incarnated as configurations of symbols" and "they symbolize things in the world because they are triggered by those things via our sense organs, and because of what they do once they are triggered." You may wonder how such a computational theory of mind accounts for our internal subjective experiences, such as the "redness" we experience when we look at an apple. It doesn't! Indeed, it is difficult to explain internal conscious experiences using any computation theory of mind, because computers don't have such experiences. From a DCS viewpoint, our subjective conscious experiences are reduced to meaningless events that play no functional role: epiphenomena.     Not all dry cognitive scientists agree on the details of the computer-brain analogy. Some believe that when we look at a red apple, there really is no redness inside our head, but rather states of nerve cells that represent attributes, like redness, that exist only in the external world. Others think that conscious experiences, like redness, are indeed generated within the nervous system but that they are irrelevant epiphenomena that play no functional role. The "redness," in this case, would be like the hum or noise given off by a computer. It is generated by the activity of the brain, but it really doesn't matter because it is irrelevant to the work done by the nerve cells and their programmed interactions. That is, subjective experiences like redness are not really necessary because they are merely the incidental by-products of a functional nervous system. There are other viewpoints, but the general consensus of dry cognitive scientists is that the brain behaves like a computer, perhaps a parallel processor, and that the faculties of mind are software programs being executed by this general-purpose machine.     In the hands of cognitive psychologists and practitioners of artificial intelligence, the DCS approach has yielded impressive results. Industrial robots now make intelligent decisions about their workplace using computer algorithms for complex scene analysis. Procedures for language comprehension, music composition, and speech synthesis continue to improve. Reasoning algorithms within chess-playing machines like Deep Blue generate moves with the flair and expertise of grand masters.     The startling fact in all of this is not the progress, which is in itself impressive, but the realization that this is all possible without any role whatsoever for conscious awareness or feelings of any kind. Now we may argue about whether computers actually think or only simulate thought, but few of us believe that they can feel, and even fewer believe that they possess any conscious awareness. Conscious awareness and feelings are the orphans of DCS. WET COGNITIVE SCIENCE Research on real brains, WCS, offers an alternative viewpoint on the nature of conscious mental states. For many years neuroscientists have known that almost every aspect of the human mind can be altered through brain stimulation, brain lesions, or small modifications in the neurochemistry of the brain. A dose of fluoxetine (Prozac) can relieve years of depression, while clozapine (Clozaril) may chase the monsters out of David's head. Feelings and perceptions are easily modified by electrical or chemical stimulation of the brain. A few molecules of LSD can elicit vivid hallucinations in which sounds may be seen and our everyday picture of reality disintegrates. Either we believe that these fantastic hallucinations are wrapped up inside a relatively simple molecule, or we are forced to conclude that they are a consequence of minor disturbances to ordinary brain chemistry. These observations suggest that our experience of reality depends more on our internal chemistry than on the world outside our skin. Indeed, input from the world "out there" is not even necessary for conscious experiences.     Imagine aliens from another planet examining the properties of human beings. They would almost certainly be surprised by the fact that we spend a third of our lives in a strange state that we call sleep. Even more surprising would be our reports of nightly hallucinations that fill our minds with vivid conscious experiences, even under conditions of total sensory deprivation. An examination of these dreams, in which strange pictures, thoughts, and feelings flit through our mind with reckless spontaneity, would compel these aliens to conclude that every aspect of conscious experience can occur in the absence of environmental input. It appears that the conscious properties of our mind, like our sensations and feelings, are firmly tied to the physical structure and chemistry of our brain, and they can arise without any input from the outside world. We can see a red apple in our dreams, at a time when no light is entering our eyes. Mental states may be activated by the senses, but they certainly don't require such inputs.     The major conclusion of WCS is that the conscious attributes of mind, like sensations and feelings, are a product of the physical and chemical organization of the brain. This viewpoint is quite different from the DCS position, which views the brain as a general-purpose computer. From a traditional DCS perspective, there is no redness inside a computer or a human brain; there are only symbolic representations of attributes that exist in the external world. In contrast, the findings of WCS clearly indicate that conscious experiences are products of the nervous system and, as such, can be evoked by chemical or electrical stimulation of the brain, even in the absence of environmental input. By itself, WCS does not explain how or why we have conscious experiences, but it clearly demonstrates that they are generated by the neural activity of a human brain.     Once it has been established that our brain can generate conscious subjective experiences in the absence of any sensory input, we should then ask if such properties exist in the external world as well. That is, do attributes like colors or sounds exist both in the external world and inside the brain? If colors and sounds do exist in the external world, then they must be inherent properties of electromagnetic radiation and air pressure waves, even in the absence of a conscious brain. But this inference poses a major problem: we now have a "redness" in the outside world that is a product of electromagnetic radiation and a second "redness," inside our brain, that can be experienced during dreams or brain stimulation, when no electromagnetic radiation strikes the retina. It doesn't matter whether we view the redness during our dreams as a recollection of a previously experienced redness or not. The point is that we are experiencing the "redness" in a dream, at a time when no electromagnetic radiation is present, so it must be a product of the activity going on inside our nervous system. And since we don't produce electromagnetic radiation of the "red" frequency inside our brain, this experience must be a second redness generated by a completely different medium: brain cells. But generating a complex attribute like redness within two entirely different physical substrates is next to impossible; one version must go! We have to give up either our conscious experience of redness or the belief that redness exists in the external world. This is a difficult choice. It is hard to believe that we live in a world that is colorless and silent and possesses only electromagnetic radiation and air pressure waves. It is absolutely impossible, however, to disavow our conscious experiences of colors and sounds. So we are forced to conclude that although the experience of redness may be evoked by a particular frequency of electromagnetic radiation striking the retina, the redness per se is not in the external world. It is exclusively a property that arises from the arrangement and interactions among nerve cells; it is an emergent property .     Emergent properties are not some mystical or mysterious products of matter; they are part and parcel of our daily experience. For example, hydrogen and oxygen are two very simple gases, and each has its own individual attributes. Hydrogen is a small molecule, and as every child knows, a balloon full of hydrogen will float up into the sky. Oxygen, which is highly reactive, combines with the wood in our fireplace and rusts the metal hinges on our garden gate. But when hydrogen and oxygen are combined to form water, a new set of properties becomes apparent. Water flows from the faucet, and unlike oxygen or hydrogen, it freezes to form snowflakes or the thin sheet of ice on a garden pond. An emergent property: is merely an attribute that arises as a consequence of the arrangement and interactions between individual components.     More complex arrangements of more complex components produce more complex emergent properties. Imagine all the parts of a car lying on the floor in a random pile. Each part has its own properties: one may be hard and smooth, another brittle and clear, still another volatile and fluid. Assembling these parts in the correct manner creates an automobile with new properties, none of which were present in the original components. The car possesses such new attributes as "acceleration," "cornering ability," and "noisiness," which depend on the arrangement and interactions among the components. In a similar manner, the properties of mind can be viewed as emergent properties resulting from the arrangement and chemical communication among nerve cells.     But why should we be concerned about emergent properties of the nervous system? After all, the hum of a refrigerator is an emergent property, but it serves no useful purpose in regulating the performance of the physical machine. Why do we need to discuss conscious experiences, if nerve cells and their interactions are really responsible for all the information processing? Any theory of mind that proposes an active role for conscious experiences is obligated to explain the function of these inner experiences and why we need to consider them. This is what David Chalmers calls the "hard problem" of consciousness.     The hard problem confronts any theory of mind that considers mental events to be a product of the physical matter/energy stuff of the nervous system--that is, all materialistic theories of mind. Here is the essence of the hard problem: if neural activity is responsible for mental events, then a hypothetical zombie, with no conscious experiences whatsoever but with the same neural organization, would be as functional as a "normal" person. That is, if nerve cells do all the physical work, conscious mental states have no additional functional role; and if they have no such role, they are irrelevant epiphenomena.     When faced with this dilemma, almost all theories of mind fall by the wayside. EVOLUTIONARY FUNCTIONALISM My viewpoint on consciousness, which I call evolutionary functionalism , is a materialistic view of the mind. To maintain this viewpoint and confront the hard problem of consciousness, it is necessary to delve into the functional role of emergent properties and explain why these faculties of mind are important, even though it is the nerve cells and their interactions that perform all the processing. A thought experiment will help to clarify the functional role of emergent properties.     Using another car analogy, let us enter a large number of cars into an imaginary race--the race of life. (See Figure 1.1.) To complete the course, each car must navigate a sharp turn in front of a brick wall, then accelerate up a hill toward the finish line. Imagine what happens. Only the small number of cars with excellent "cornering ability" and "acceleration" will be able to complete the course. (For the purpose of the thought experiment, all the drivers are equally competent.) A factory of robotic assemblers constructs new cars based on the designs of the winners; evolution is now under way. Generation after generation, the robots build new models by combining parts from the cars that completed the prior race.     The important point of the thought experiment is that successful cars are being selected on the basis of their emergent properties--acceleration and cornerning ability--and only indirectly on the basis of their physical structure or the design of their individual components. A variety of physical designs, such as engine size and placement, carburetor design, body contours, may contribute to these emergent characteristics. In the evolutionary paradigm, however, selection acts on the emergent properties, and the actual physical design of future cars will be a consequence of the successful, functional emergent properties that allowed their predecessors to complete the course. After several generations it is apparent that although the physical components do all the work, their arrangement--how they get to be organized the way they are--is a consequence of the emergent properties arising from that arrangement. Analogously, nerve cells are certainly the active agents in the nervous system, but their organization depends on the survival value of the emergent properties that arise from that organization. Over the long course of evolution, the functional attributes of the mind have been responsible for shaping the physical and chemical structure of brains. From this viewpoint, functional consequences dictate structural design.     For a biological example, consider the case of the peppered moths (Biston betularia) in Birmingham, England, at the time of the Industrial Revolution. Before the city and its surroundings became polluted by industrial waste, the moths were predominately white. As the environment became blackened, birds easily detected the white moths. As white moth numbers dwindled, a black moth population exploded. Note that natural selection did not favor either white or black moths; rather, the selection process favored the emergent property of "camouflage." Whiteness and blackness have no inherent value in and of themselves; it is "camouflage" that has survival value. Thus physical structures are merely secondary consequences, of their functional consequences, and functional attributes direct structural design. An enzyme is simply a protein unless it plays a functional role. But if a protein has a functional role--in digestion, for example--then it has survival value, and any gene that codes for this enzyme will increase in future generations.     The hard problem of consciousness has now been partially resolved but the specific functions of the emergent properties of mind still require some elucidation.     Not every emergent property is functional; "noisiness" played no role in our imaginary car race. In biological organisms only the functional attributes that ensure survival and reproduction will eventually be transmitted to future generations. From this perspective, the attributes of mind are not just any emergent properties of the neural organization; they are those functional emergent properties that enhance biological survival. That is, of all the emergent properties that could emanate from neural networks, only a subset will be selected: the subset that ensures the survival of DNA that can design brains that possess these emergent properties. Rather than creating a general-purpose computer, this iterative design process ensures that the evolved attributes of mind have a very special function--gene survival. Nor are these attributes independent of their biological underpinnings, as DCS suggests; rather they are selected because they help to preserve and perpetuate the biological tissue to which they owe their very existence. Relentless selection slowly but inexorably leads to adaptive or at least "satisficing" functional design. This simple premise has profound implications for understanding the nature and origin of all conscious experiences. More specifically, the design and functional significance of human feelings now become apparent.     If rotten eggs smell bad, tissue damage causes pain, or sugar tastes sweet, it is not because hydrogen sulfide gas has a foul smell, or because pain is waiting to escape from the point of a needle as it enters the skin, or because sweetness is a property of sugar molecules. Rather, it is because the human brain has evolved a neural organization that can generate pleasant or unpleasant sensations for those aspects of the world that are a benefit or detriment to gene survival. That is, only organisms that have evolved such evaluative subjective feelings have been successful in transmitting their genes to successive generations. The individual organism need not be aware of the relationship between a foul odor and bacterial contamination, between tissue damage and infection, or between a sweet taste and the manufacture of ATP (the energy molecule in the body); natural selection has already established this relationship between emergent conscious feelings and gene survival. Most of us are oblivious to the fact that the energy required to contract our muscles, transport substances across our cell membranes, and make the important chemicals required by every living cell of our body is supplied by breaking one of the high-energy phosphate bonds of ATP to produce ADP. However, we don't need to know or understand these mechanisms in order to survive; that knowledge is already part of our biological nature.     Sugars, a very rich source of dietary energy, simply taste good. Sweetness, however, is not a property of a sugar molecule; it is an evolved emergent property of our brain. Such sensations provide us with an immediate evaluation of sensory events, even in the absence of any understanding of their biological importance or their evolutionary origins. Our discomfort at high or low temperatures and the unpleasant smell of our waste products are both evolved emergent properties that were elicited by environmental events that consistently posed a threat to biological survival in ancestral environments. Individuals require no knowledge of these relationships, because natural selection has already forged the link between our conscious feelings and gene survival. We are aware of our proximate design , our sensations, and our feelings, but we have little awareness of how these emergent properties are related to the survival of our genes, our ultimate design .     Normally, we don't ask why we don't see air pressure waves or hear electromagnetic radiation, or why we don't generate a completely different subjective experience (which we can't imagine) in the presence of gamma radiation or when we are traveling at a constant velocity. Under those circumstances we would perceive our world quite differently. The way we do see it, therefore, requires some justification. But the illusion of naive realism is so powerful and ubiquitous that we come to believe that objects really are red, or hot, or bitter, or sweet, or beautiful, and we usually do not ask how or why we impose this structure on our physical world, or how this structure relates to our biological survival. We talk about the world around us as if it is full of light and sounds and tastes and smells. The physical world certainly contains electromagnetic radiation, air pressure waves, and chemicals dissolved in air or water, but not a single light or sound or smell or taste exists without the emergent properties of a conscious brain. Our conscious world is a grand illusion! INTERACTING WITH THE PHYSICAL WORLD If we have learned anything from twentieth-century physics, it is the realization that the physical world is composed of energy, some of which is currently in a form that we call matter . A subjective experience, like "redness," does not exist in this external world; rather, the brain has evolved to generate this particular experience in the presence of a specific frequency of electromagnetic radiation. A completely different experience, "greenness," is produced in response to a very similar frequency. Indeed, the physical difference in wavelength between "red" and "green" is a mere 150 billionths of a meter; they are essentially identical. In contrast, the room that you are in is filled with the infrared (IR) emissions from your body, plus signals from the local radio station (AM). Although the AM signals are more than a billion times the wavelength of the IR radiation, neither signal is detected, and no discrimination is made between them. Our senses and subjective experiences seem to have evolved to generate a nonlinear representation of the energy/matter that exists "out there." While some specific energy/matter configurations elicit vivid subjective experiences, others are completely ignored. What biological benefits could have led to this arrangement?     For most animals, visual perception is limited to detecting and discriminating within a small range of electromagnetic frequencies centered around those reflected by the leaves of plants. This is not surprising since the survival of most animals depends on a food chain based on the ability of plants to convert solar energy into sugars using photosynthesis. The middle of our visible spectrum, which we perceive as green, corresponds to the frequencies reflected by the chlorophyll molecule when exposed to the incident radiation from our sun, or so-called white light. However, the incident radiation from the sun varies with weather conditions, so to compensate for these variations, it becomes necessary for animals to be able to detect other frequencies. Direct sunshine contains a wide range of frequencies, but radiation reflected from the sky is mainly in the higher frequency range (the sky appears blue) while lower frequencies dominate when the sun's radiation is scattered by particulate matter (the sky often appears red at sunrise or sunset). Under these different environmental conditions, the frequencies reflected by a "green" leaf vary considerably. If our perception of a leaf's color were simply a function of the reflected radiation, then the leaf would change color at sunset or when a cloud moved in front of the sun, causing it to be illuminated by radiation reflected from the sky. Remarkably, this doesn't happen. We possess a mechanism for color constancy that can compensate for these variations in incident radiation. To perceive a leaf as green under all the different conditions on earth, it is necessary to detect and compensate for the range of incident radiation that commonly bathes our planet. That is, in addition to "green" detectors, we require both "red" and "blue" detectors. The cones of our retina, and our conscious experiences of color, seem to have evolved in response to the very specific and perhaps unique problems encountered by diurnal animals that depend on a chlorophyll-based food chain on a planet that possesses particular atmospheric conditions.     If an organism experiences one emergent property (redness) when exposed to one frequency of electromagnetic radiation and a completely different emergent property (greenness) when exposed to a frequency that is physically almost identical, then it is not only discriminating between these signals but also exaggerating the difference between them. Such an organism enjoys the functional benefits of this discrimination, so the retinal and neural organization underlying these emergent properties will continue to be refined over generations. Similarly, an organism that experiences a discrete conscious feeling (sweetness) when presented with a valuable resource (sugars) and a very different feeling (sourness) when faced with a common waste product (acids) will pass on to future generations the neural circuitry that underlies this ability to form discriminating evaluations. There is no dualism here: The nervous system does all the processing, but its organization is a result of natural selection favoring the functionality arising from that particular organization. By favoring conscious subjective experiences that clearly discriminate between important environmental variables, natural selection, over generations, has continued to improve the neural machinery capable of generating such experiences.     What is true for the subjective quality of an experience, like sweetness or sourness, is also true for its subjective intensity: a bright light, a strong taste, a loud noise. In the external world, the actual physical attribute of a signal that changes with perceived intensity is quite different across these different sensory domains. In vision, for example, the intensity of a light is correlated with the number of photons striking the receptors of the retina, whereas the intensity of a taste varies with the concentration of molecules in a solvent, and the intensity of a sound depends on changes in air pressure over time. These various physical changes would have nothing in common except for the fact that our evolved sensory transducers convert such signals into an increased number of nerve impulses per second within the visual, gustatory, or auditory pathways, respectively, and this increased neural input evokes a subjective change in intensity. Our conscious experience, not any specific change in the physical world, defines the change in intensity of a signal. Although an increase in the energy of an environmental signal is often correlated with an increase in subjective intensity, this is not always the case. For example, a decrease in the kinetic energy of molecules striking the skin evokes an increase in subjective coldness, while a "blue" photon, which has more energy than a "red" photon, evokes a change in color rather than a change in intensity. Both the qualitative and quantitative attributes of the physical world appear to be defined, not by the events in the world that activate them, but by the evolved emergent properties of our nervous system.     The naive realism we started with--that apples appear red because they really are red--has now undergone several major modifications. According to DCS, the redness was "out there," and only symbolic representations existed, or were important, in the nervous system. The WCS view brought the redness back into the head as an emergent property. Finally, evolutionary functionalism eliminated the redness "out there" altogether, leaving it exclusively as an evolved emergent property of the nervous system. Over generations, by favoring emergent properties that enhance gene survival, natural selection has forged the neural machinery capable of generating such experiences. From this perspective, nerve cells are certainly the active agents in the nervous system, but they are organized the way they are because natural selection has favored the functional emergent properties that arise from that arrangement. It is always function--gene survival--that dictates structural design. If functional conscious experiences shaped and refined the organization of the nervous system, then the zombie we discussed earlier, with the same neural design as a conscious brain, would inevitably be conscious. At last the hard problem of consciousness has been defused, leaving us with a view of conscious experience as an active filter, or discriminant amplifier, with enormous functional benefits. This is the essence of evolutionary functionalism. EVALUATING EVOLUTIONARY FUNCTIONALISM Evolutionary functionalism faces the same problems as those that face astronomers: we simply have no way to replay and hence know the actual sequence of events that were responsible for creating the current state of the universe, and we have no method for reconstructing the evolutionary history of the human mind. Despite this limitation, however, two different approaches can provide strong support for the evolutionary viewpoint: computer simulation, and convincing evidence for adaptive historical design.     The first approach involves simulating the evolution of emergent properties in a computer. Computer models provide a rigorous test of any proposed origin or function of emergent attributes. If we believe, for example, that feelings evolved because they played a specific role in controlling some aspect of behavior, then it should be possible to evaluate this proposition using a computer simulation. Genetic algorithms provide a simple and effective tool for simulating the evolution of feelings in a computer; they also provide a novel method for evaluating evolutionary functionalism. The theoretical basis of such simulations, and their results, are described in Chapters 2, 3, and 4.     The second approach is to examine current emergent properties, such as feelings, to uncover their historical design. Theoretically, emergent properties evolved because they provided solutions to problems that were consistently present and posed habitual threats, or offered benefits, to biological survival in specific ancestral environments. That is, selection pressures acting over prolonged historical periods--the environments of evolutionary adaptedness (EEAs)--were responsible for the different aspects of our satisficing design. The EEA responsible for the evolution of an emergent property like "redness" for example, was certainly much earlier and quite different from the EEA that led to the evolution of a feeling like "pride." Furthermore, there is no a priori reason why an adaptation acquired in one EEA should necessarily be adaptive in another.     An evolutionary theory of feelings, therefore, should explain how each feeling evolved in response to specific problems that organisms encountered during its EEA. It should also explain why we have so many different kinds of feelings, like love, fear, and anger. This type of explanation is most convincing when it accounts for unusual characteristics that are not easily explained from alternative perspectives. As Stephen Jay Gould has persuasively argued in The Panda's Thumb , the best evidence for historical design is the existence of characteristics that are no longer useful but that had a clear ancestral function. For example, the residual legs on a snake are an unmistakable indication of the snake's evolutionary history. In a similar manner, the existence of a feeling that had clear historical value, but is now nonfunctional or even maladaptive, would offer strong support for an evolutionary perspective. Evidence supporting the adaptive historical design of human feelings is discussed in Chapters 5, 6, 7, and 8. THE ADAPTIVE ILLUSION Adopting an evolutionary viewpoint on the attributes of mind solves three major problems that confront any theory that attempts to explain the nature and origin of conscious experiences. First, it resolves the "double redness" paradox by eliminating the redness in the external world, holding that all conscious experiences exist exclusively as emergent properties of neural organization. Second, it provides a functional role for these conscious experiences. They are the emergent properties of the nervous system that have been selected because they amplify and discriminate between attributes of the world that are biologically important, and as I will discuss later, these discriminations play a central role in the adaptive mechanisms of learning and reasoning. Third, it explains why sensory feelings, like sweetness or saltiness, are evoked by environmental events that are clearly important for gene survival. In the absence of an evolutionary perspective, the existence of such congruous relationships would require the assumption of a preestablished harmony between conscious experiences and biological survival. Such preordained explanations fall outside the realm of natural science.     When conscious experiences are viewed as properties of biological tissue and not rigid properties of the "outside" world, then they can be continuously shaped and refined by natural selection. But natural selection doesn't "care" whether such experiences are accurate reflections of our external reality; it "cares" only about biological usefulness--the extent to which they enhance the survival and reproduction of organisms that possess them relative to those that do not. Limited by this single functional constraint, minds have evolved a fantastic array of emergent experiences, which in turn provide the raison d'être for neural organization. Relentless selection inexorably demands that the attributes of mind evolve to enhance discriminations when they are functionally useful, and ignore them when unimportant. As a consequence, organisms have evolved subjective experiences that impose a distorted but functionally useful view of the world "out there," and at the same time have evolved the neural machinery that underlies this interpretation of reality.     The essence of our "satisficing" design is that our senses filter out most of the background energy/matter in the world; we don't smell clean air, taste pure water, or see the vast expanse of the electromagnetic spectrum. With our receptors tuned only to specific energy bandwidths, we psychophysically scale our world, making precise discriminations over the small but biologically important ranges of intensity and frequency while minimizing or ignoring differences toward the extremes of our sensory domains. What we do detect elicits vivid conscious experiences that are gross distortions of what exists "out there." Consciousness amplifies those attributes of the physical world (and the social world, as we will see) that are biologically relevant. Our amplified and distorted picture of the world may be a powerful illusion, but it is neither arbitrary nor random; the faculties of mind were adaptively designed.     Consider a world without consciousness. The darkness is a bubbling cauldron of energy and vibrating matter, locked in the incessant dance of thermal agitation. Through shared electrons or the strange attraction of unlike charges, quivering molecules, not free to roam, absorb and emit their characteristic quantal packages of energy with the surrounding fog. Free gas molecules, almost oblivious to gravity but buffeted in all directions by their neighbors, form swirling turbulent flows or march in zones of compression and expansion, according to the dictates of oscillating substrates. A massive solar flux and cosmic radiation from events long past crisscross space with their radiant energy and silently mix with the thermal glow of living creatures, whose hungry metabolic systems pour their infrared waste into the chaotic milieu. But within the warmth of their sticky protein bodies, the dim glow of consciousness is emerging to impose its own brand of organization on this turbulent mix of energy/matter. The active filter of consciousness illuminates the darkness, discards all irrelevant radiation, and in a grand transmutation converts and amplifies the relevant. Dead molecules erupt into flavors of bitterness or sweetness, electromagnetic frequencies burst with color, hapless air pressure waves become the laughter of children, and the impact of a passing molecule fills a conscious mind with the aroma of roses on a warm summer afternoon.     In a sense, like David, we are all hallucinating. But David's conscious experiences were not in harmony with the physical world around him; his hallucinations were not adaptive. His condition may have been the result of a small chemical difference in a transmitter molecule, dopamine, or its receptor sites. This small change in brain chemistry shattered his reality. We have no particular a priori reason to value one chemistry over any other, except that our normal chemistry has been selected as part of the satisficing design that has permitted survival and reproduction on our small planet. We may not possess the optimal design for visualizing multidimensional space or warps in space-time. Nevertheless, despite their limitations, our conscious sensations and feelings are not irrelevant epiphenomena; they are remarkable emergent properties that owe their existence to that master tinkerer, natural selection. Copyright © 1999 Victor S. Johnston. All rights reserved.

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