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Gray ch01

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  2. 2. 000-023_CH001_12708_Brochure.qxp 11/11/05 9:56 AM Page 1 Background to the Study of Psychology “Know thyself.” These two words were inscribed on the shrine of the Oracle of Apollo, at Delphi, Greece, in the sixth century b.c. Throughout recorded history, human beings have striven to understand the nature of being human, to fathom the mysteries of the human mind and human behavior. Today that endeavor is pursued as a science, the science of psychology. In this first, background unit, we examine some fundamental ideas that helped to bring about a science of psychology, and we preview some of the methods that help to make part 1 psychology a science. Foundations for the Study of Psychology chapter1 Three Foundation Ideas for Psychology: A Historical Overview The Idea of Physical Causation of Behavior T he human being, as far as any human being can tell, is the only creature that contemplates itself. We not only think, feel, dream, and act but also wonder how and why we do these things. Such contemplation has taken many forms, ranging from just plain wondering to folk tales and pop- The Idea That the Mind and Behavior ular songs, to poetry and literature, to formal theologies and Are Shaped by Experience philosophies. A little more than a century ago, human self- The Idea That the Machinery of Behavior and Mind Evolved contemplation took a scientific turn, and we call that science Through Natural Selection psychology. Welcome! Welcome to Psychology and to psychology—that is, The Scope of Psychology to this book and to the field of study it is about. I hope you will Varieties of Explanations in enjoy them both. The big question of psychology is one of the Psychology, and Their Application to Sexual Jealousy most fascinating that anyone can ask: What makes people feel, The Connections of Psychology to think, and behave the way they do? In this book you will read Other Scholarly Fields about many routes toward answering that big question, and you Psychology as a Profession will discover many dozens of specific findings and ideas that help to answer it. Thoughts About Using This Book It is useful to begin with a formal definition of our subject: and Its Special Features Psychology is the science of behavior and the mind. In this defi- nition behavior refers to the observable actions of a person or an animal. Mind refers to an individual’s sensations, percep- tions, memories, thoughts, dreams, motives, emotional feel- ings, and other subjective experiences. It also refers to all of the unconscious knowledge and operating rules that are built into or stored in the brain, and that provide the foundation for or- ganizing behavior and conscious experience. Science refers to all attempts to answer questions through the systematic collec- tion and logical analysis of objectively observable data. Most of the data in psychology are based on observations of behavior, because behavior is directly observable and mind is not; but psychologists often use those data to make inferences about the mind. In this opening chapter, I want to do three things, all aimed at helping to prepare you for the rest of the book. First, I want to present you with a little bit of the history and philosophy
  3. 3. 000-023_CH001_12708_Brochure.qxp 11/11/05 9:56 AM Page 2 2 PART 1 ■ BACKGROU ND TO THE STU DY OF PSYCHOLOGY that predate and underlie modern psychology. More specifically, I will say some- thing about the historical origins of three ideas that are so basic to our science that I refer to them as “foundation ideas for psychology.” Second, I want to tell you something about the scope of modern psychology, especially about the various lev- els of analysis that psychologists use in learning about and explaining mental expe- riences and behavior. Third, I want to tell you something about the features of this book and how you might use them to maximize your enjoyment of it and your learning from it. I put that section last, because I thought you might learn more from it after you have read a bit into the book than you would if it came first. If you prefer to read that section first, please do. It starts on page 19. 1 <<< There is one feature of the book that I want you to notice right now, however. In How might the focus questions (such as the margins of the text, throughout the book, you will find numbered focus questions. this one) in the text’s margins be used to The first such question appears in the margin next to the paragraph you are reading guide initial reading and review? right now. These are the questions that I am trying to answer in the text, and they are also good test questions. An effective way to study this book is to read and think about each focus question, as you come to it, before you read the adjacent paragraphs of text, which are aimed at answering that question. This method of study will help you focus your attention on the text and understand and remember what you read. If you read with the active intention of answering the focus questions, your mind is less likely to drift, and you are more likely to understand and think about what you read than if you read passively just to “learn” or “absorb” the material. Three Foundation Ideas for Psychology: A Historical Overview The founding of psychology as a formal, recognized, scientific discipline is com- monly dated to 1879, when Wilhelm Wundt, in Germany, opened the first university-based psychology laboratory. At about that same time, Wundt also au- thored the first textbook of psychology and began mentoring the first official grad- uate students of psychology. The first people to earn Ph.D. degrees in psychology were Wundt’s students. But the roots of psychology predate Wundt. They were developed by people who called themselves philosophers, physicists, physiologists, and naturalists. In this section we shall examine three fundamental ideas of psychology, all of which were conceived of and debated before the establishment of psychology as a recog- René Descartes Descartes’s specula- tions, in the seventeenth century, nized scientific discipline. Briefly, the ideas are these: about reflexes and the interaction of 1. Behavior and mental experiences have physical causes, so they are amenable the body and soul in controlling volun- to scientific analysis. tary actions were an important step toward a scientific analysis of human 2. The way a person behaves, thinks, and feels is modified, over time, by the per- behavior. son’s experiences in his or her environment. 3. The body’s machinery, which produces behavior and mental experiences, is a product of evolution by natural selection. The Idea of Physical Causation of Behavior Before a science of psychology could emerge, people had to conceive of and accept the idea that questions about human behavior and the mind can, in principle, be answered scientifically. Seeds for this conception can be found in the writings of some of the ancient Greeks, who speculated about the senses, the human intellect, and the physical basis of the mind in ways that seem remarkably modern. But such ideas became dormant in the Middle Ages and did not begin to sprout again until Corbis-Bettmann the fifteenth century (the Renaissance) or to take firm hold until the eighteenth century (the Enlightenment). Philosophy was tightly bound to religion through the seventeenth century. The church maintained that each human being consists of two distinct but intimately
  4. 4. 000-023_CH001_12708_Brochure.qxp 11/11/05 9:56 AM Page 3 CHAPTER 1 ■ FOU N DATIONS FOR TH E STU DY OF PSYCHOLOGY 3 conjoined entities, a material body and an immaterial soul—a view referred to today as dualism. The body is part of the natural world and can be studied scientif- ically, just as inanimate matter can be studied. The soul, in contrast, is a supernat- ural entity that operates according to its own free will, not natural law, and therefore cannot be studied scientifically. This was the accepted religious doctrine, which—at least in most of Europe—could not be challenged publicly without risk of a charge of heresy and consequent execution. Yet the doctrine left some room for play, and one who played dangerously near the limits was the great French mathematician, physiologist, and philosopher René Descartes (1596–1650). Descartes’s Version of Dualism: Focus on the Body Prior to Descartes, most dualists assigned all the interesting qualities of the human >>> 2 being to the soul. The soul was deemed responsible for the body’s heat, for its abil- What was Descartes’s version of dualism? ity to move, for life itself. In Treatise of Man (1637/1972), and even more explicitly How did it help pave the way for a science of psychology? in The Passions of the Soul (1649/1985), Descartes challenged this view. He had per- formed dissections of animals and of human cadavers, was familiar with research on the flow of blood, and began to regard the body as an intricate, complex machine that generates its own heat and is capable | figure 1.1 | Descartes’s depic- of moving even without the influence of tion of a reflex Descartes believed the soul. Although little was known about that reflexes occur through purely the nervous system in his time, Descartes’s mechanical means. In describing this figure, Descartes (1637/1972) suggest- conception of the mechanical control of ed that the fire causes movement in movement resembles our modern under- the nearby particles of skin, pulling on standing of reflexes, which are involuntary a “thread” (that runs “C” to “C” along responses to stimuli (see Figure 1.1). the back) going to the brain, which, in Descartes believed that even quite com- turn, causes a pore to open in the plex behaviors can occur through purely brain, allowing fluid to flow through a mechanical means, without involvement “small conduit’’ to the muscles that withdraw the foot. What Descartes Corbis-Bettmann of the soul. Consistent with church doc- called a “thread’’ and a “small conduit’’ trine, he contended that non-human ani- are today called nerves, and we now mals do not have souls, and he pointed out know that nerves operate through a logical implication of this belief: Any ac- electrical means, not through physical tivity performed by humans that is qualita- pulling or the shunting of fluids. tively no different from the behavior of a non-human animal can, in theory, occur without the soul. If my dog (who can do some wondrous things) is just a machine, then a good deal of what I do might occur purely mechanically as well. In Descartes’s view, the one essential ability that I have but my dog does not is thought, which Descartes defined as conscious deliberation and judgment. Whereas previous philosophers ascribed many functions to the soul, Descartes ascribed just one—thought. But even in his discussion of thought, Descartes tended to focus on the body’s machinery. To be useful, thought must be responsive to the sensory input channeled into the body through the eyes, ears, and other sense organs, and it must be capable of directing the body’s movements by acting on the muscles. How can the thinking soul interact with the physical machine—the sense or- gans, muscles, and other parts of the body? Descartes suggested that the soul, though not physical, acts on the body at a particular physical location. Its place of action is a small organ (now known as the pineal body) buried between the two hemispheres (halves) of the brain (see Figure 1.2). Threadlike structures, which we now call nerves, bring sensory information by physical means into the brain, where the soul receives the information and, by non-physical means, thinks about it. On the basis of those thoughts, the soul then wills movements to occur and exe- cutes its will by triggering physical actions in nerves that, in turn, act on muscles. Descartes’s dualism, with its heavy emphasis on the body, certainly helped >>> 3 open the door for a science of psychology. It is a popular theory among non- Why was Descartes’s theory, despite its scientists even today, because it acknowledges the roles of sense organs, nerves, intuitive appeal, unsuitable for a complete psychology? and muscles in behavior without violating people’s religious beliefs or intuitive feelings that conscious thought occurs on a non-physical plane. But the theory has
  5. 5. 000-023_CH001_12708_Brochure.qxp 11/11/05 9:56 AM Page 4 4 PART 1 ■ BACKGROU ND TO THE STU DY OF PSYCHOLOGY serious limitations, both as a philosophy and as a foundation for a science of psychology. As a philosophy, it stumbles on the ques- tion of how a non-material entity (the soul) can have a material ef- fect (movement of the body), or how the body can follow natural Cambridge, MA: Harvard University Press. law and yet be moved by a soul that does not (Campbell, 1970). As Descartes, R. (1972). Treatise of Man. a foundation for psychology, the theory sets strict limits, which few psychologists would accept today, on what can and cannot be understood scientifically. The whole realm of thought and all be- haviors that are guided by thought are out of bounds for scientific analysis if they are the products of a willful soul. Thomas Hobbes and the Philosophy of Materialism At about the same time that Descartes was developing his machine-oriented version of dualism, an English philosopher | figure 1.2 | Descartes’s depiction of how the soul named Thomas Hobbes (1588–1679) was going much further. It receives information through the eyes Descartes should be no surprise that an Englishman, not a Frenchman, was believed that the human soul is housed in the pineal gland, depicted here as the tear-shaped structure in the center of first to break from dualism entirely. The church and state were the head. In describing this figure, Descartes (1637/1972) constantly feuding in seventeenth-century England, and inklings suggested that light from the arrow enters the eyes and of democracy were emerging. Hobbes had been employed as a opens pores in structures that we now know as the optic tutor to the future King Charles II and, when the latter came to nerves. Fluid flows from the eyes through the opened power, enjoyed royal protection. When a committee of bishops pe- pores, causing movement in the pineal gland, which, in titioned that Hobbes be burned to death for his blasphemous book Descartes’s words, “renders the idea’’ of the arrow to the Leviathan, Hobbes received instead a stern warning (Hunt, 1993). soul. The church burned copies of his book, but Hobbes, promising not to repeat his heresy, lived to the ripe age of 91. 4 <<< In Leviathan, and in a shorter work called Human Nature, Hobbes argued that How did Hobbes’s materialism help lay the spirit, or soul, is a meaningless concept and that nothing exists but matter and en- groundwork for a science of psychology? ergy, a philosophy now known as materialism. In Hobbes’s view, all human be- havior, including the seemingly voluntary choices we make, can in theory be understood in terms of physical processes in the body, especially the brain. Conscious thought, he maintained, is purely a product of the brain’s machinery and therefore subject to natural law. With this philosophy there is no theoretical limit to what psychologists might study scientifically. Most of Hobbes’s work was directed toward the implications of materialism for politics and government, but his ideas helped inspire, in England, a school of thought about the mind known as empiricism, to which we shall soon turn. Nineteenth-Century Physiology: Learning About the Machine The idea that the body, including the brain, is a machine, amenable to scientific study, helped to promote the science of physiology—the study of the body’s ma- chinery. By the beginning of the nineteenth century, considerable progress had been made in this endeavor, and during that century discoveries were made about the nervous system that contributed significantly to the origins of scientific psychology. Increased Understanding of Reflexes One especially important development for the later emergence of psychology was an increased understanding of reflexes. The basic arrangement of the nervous system—consisting of a central nervous sys- tem (brain and spinal cord) and peripheral nerves that connect the central nervous A seventeenth-century mechanical man Mechanical clocks represented the pinnacle of technological achievement of the Smithsonian Institute seventeenth century, comparable to computers today. For amusement, clocklike mechanisms were used to operate robotic, humanoid figures, as illustrated here. Such mechanical men helped to inspire, in Descartes and Hobbes, the idea that actual human beings might also operate by mechanical means, not requiring a nonmaterial spirit to move them.
  6. 6. 000-023_CH001_12708_Brochure.qxp 11/11/05 9:56 AM Page 5 CHAPTER 1 ■ FOU N DATIONS FOR TH E STU DY OF PSYCHOLOGY 5 system to sense organs and muscles—was well understood by the beginning of the >>> 5 nineteenth century. In 1822 in France, François Magendie demonstrated that How did the nineteenth-century under- nerves entering the spinal cord contain two separate pathways: one for carrying standing of the nervous system inspire a theory of behavior called reflexology? messages into the central nervous system from the skin’s sensory receptors and one for carrying messages out to operate muscles. Through experiments with ani- mals, scientists began to learn about the neural connections that underlie simple reflexes, such as the automatic withdrawal response to a pin prick, and found brain areas that, when active, could either enhance or inhibit such reflexes. Some of these physiologists began to suggest that all human behavior occurs through reflexes, that even so-called voluntary actions are actually complex re- flexes involving higher parts of the brain. One of the most eloquent proponents of this view, known as reflexology, was the Russian physiologist I. M. Sechenov. In his monograph Reflexes of the Brain, Sechenov (1863/1935) argued that every human action, “[b]e it a child laughing at the sight of toys, or . . . Newton enunciating universal laws and writing them on paper,” can in theory be understood as a reflex. All human actions, he claimed, are initiated by stimuli in the environment. The stimuli act on a person’s sensory receptors, setting in motion a chain of events in the nervous system that culminates in the muscle movements that constitute the action. Sechenov’s work inspired another Russian physiologist, Ivan Pavlov (1849–1936), whose work on reflexes played a critical role in the development, in North America, of a school of thought in psychology called behaviorism (discussed in Chapter 4). The Concept of Localization of Function in the Brain Another important ad- >>> 6 vance in nineteenth-century physiology was the concept of localization of function How did discoveries of localization of func- in the brain, the idea that specific parts of the brain serve specific functions in the tion in the brain help establish the idea that the mind can be studied scientifically? production of mental experience and behavior. In Germany, Johannes Müller (1838/1965) proposed that the different qualities of sensory experience come about because the nerves from different sense organs excite different parts of the brain. Thus we experience vision when one part of the brain is active, hearing when another part is active, and so on. In France, Pierre Flourens (1824/1965) per- formed experiments with animals showing that damage to different parts of the brain produces different kinds of deficits in animals’ ability to move. And Paul Broca (1861/1965), also in France, published evidence that people who suffer in- jury to a very specific area of the brain’s left hemisphere lose the ability to speak but do not lose other mental abilities. All such evidence about the relationships be- tween mind and brain helped lay the groundwork for a scientific psychology, be- cause it gave substance to the idea of a material basis for mental processes. Early evidence for localization of function Shown here is the pre- served brain of Paul Broca’s patient known as Tan, who lost his ability to Paris Museum speak after suffering brain damage. The damage is in the left frontal lobe, in an area now called Broca’s area (discussed in Chapter 5).
  7. 7. 000-023_CH001_12708_Brochure.qxp 11/11/05 9:56 AM Page 6 6 PART 1 ■ BACKGROU ND TO THE STU DY OF PSYCHOLOGY The Idea That the Mind and Behavior Are Shaped by Experience Besides helping to inspire research in physiology, the materialist philosophy of seventeenth-century England led quite directly to a school of thought about the mind known as British empiricism, carried on by such British philosophers as John Locke (1632–1704), David Hartley (1705–1759), James Mill (1773–1836), and John Stuart Mill (1806–1873). Empiricism, in this context, refers to the idea that human knowl- edge and thought derive ultimately from sensory experience (vision, hearing, touch, and so forth). If we are machines, we are machines that learn. Our senses provide the input that allows us to acquire knowledge of the world around us, and this knowledge allows us to think about that world and behave adaptively within it. The essence of empiricist philosophy is poetically expressed in the following often-quoted passage from Locke’s An Essay Concerning Human Understanding (1690/1975, p. 104): Let us suppose the mind to be, as we say, white paper, void of all characters, without any ideas; how comes it to be furnished? Whence comes it by that vast store, which the busy and boundless fancy of man has painted on it, with an almost endless variety? Whence has it all the materials of reason and knowledge? To this I answer, in one word, from ex- perience. In that, all our knowledge is founded; and from that it ultimately derives itself. The Empiricist Concept of Association by Contiguity 7 <<< In keeping with materialist philosophy, Locke and the other British empiricists How did the British empiricists explain theargued that thoughts are not products of free will, but reflections of one’s experi- origin of complex ideas and thoughts? ences in the physical and social environment. All the contents of the mind derive What role did the law of association by contiguity play in their philosophy? from the environment and bear direct relationship to that environment. According to the empiricists, the fundamental units of the mind are elementary ideas, which derive directly from sensory experiences, and these become linked together, in lawful ways, to form complex ideas and thoughts. The most basic operating principle of the mind’s machinery, according to the empiricists, is the law of association by contiguity, an idea originally proposed by Aristotle in the fourth century B.C. Contiguity refers to closeness in space or time, and the law of association by contiguity can be stated as follows: If a person expe- riences two environmental events (stimuli, or sensations) at the same time or one right after the other (contiguously), those two events will become associated (bound together) in the person’s mind, such that the thought of one event will, in © Lake County Museum / Corbis the future, tend to elicit the thought of the other. As a simple illustration, consider a child’s experiences when seeing and biting into an apple. The child receives, from the apple, a set of sensations, which pro- duce in her mind such elementary ideas as red color, spherical shape, and sweet and tart taste. The child may also, at the same time, hear the sound apple emanat- ing from the vocal cords of a nearby adult. Because all these sensations are experi- enced together, they become associated in the child’s mind. Together, they form the complex idea “apple.” Because of association by contiguity, the thought of any A complex idea To the empiricist of the sensory qualities of the apple will tend to call forth the thought of all the philosophers, even as simple a con- apple’s other sensory qualities. Thus when the child hears apple, she will think of cept as that of “apple” is a complex the red color, the spherical shape, and the sweet, tart taste. Or, when the child sees idea, consising of a set of elementary an apple, she will think of the sound apple and imagine the taste. sensations—of shape, color, and taste—that become associated in the The empiricists contended that even their own most complex philosophical person’s mind through experiences ponderings could, in theory, be understood as amalgams of elementary ideas that with apples. became linked together in their minds as a result of contiguities in their experi- ences. John Stuart Mill (1843/1875) referred to this sort of analysis of the mind as mental chemistry. Complex ideas and thoughts are formed from combinations of el- ementary ideas, much as chemical compounds are formed from combinations of chemical elements. 8 <<< As you will discover in Chapters 4 and 9 of this textbook, the law of association What influence has empiricist philosophy by contiguity is still regarded as a fundamental principle of learning and memory. had on psychology? More broadly, most of psychology—throughout its history—has been devoted to
  8. 8. 000-023_CH001_12708_Brochure.qxp 11/11/05 9:56 AM Page 7 CHAPTER 1 ■ FOU N DATIONS FOR TH E STU DY OF PSYCHOLOGY 7 the study of the effects of experience on one’s thoughts, feelings, and behavior. As examples, social psychologists study the ways in which people are influenced by their social environment; cultural psychologists study differences among people that arise from growing up in different cultures; developmental psychologists are interested in the experiences that lead children to acquire language and to think in ever more complex ways; clinical psychologists are interested in the experiences that can lead to mental disorders or can help one overcome such disorders; and cognitive psychologists strive to understand the mental machinery that makes learning and memory possible. The impact of empiricist philosophy on psychology has been enormous. The Nativist Response to Empiricism For every philosophy that contains part of the truth, there is an opposite philoso- phy that contains another part of it. The opposite of empiricism is nativism, the view that some knowledge and rules of operation are native to the human mind— that is, are inborn and do not have to be acquired from experience. Take a sheet of white paper and present it with all the learning experiences that >>> 9 a normal human child might encounter (a suggestion made by Ornstein, 1991). Why is the ability to learn dependent on The paper will learn nothing. Talk to it, sing to it, give it apples and oranges, take it inborn knowledge? In Kant’s nativist phi- losophy, what is the distinction between for trips in the country, hug it and kiss it; it will learn nothing about language, a priori knowledge and a posteriori music, fruit, nature, or love. To learn anything, any entity must contain some ini- knowledge? tial machinery, already built into it. At a minimum, that machinery must include an ability to sense some aspects of the environment, some means of interpreting and recording those sensations, some rules for storing and combining those sen- sory records, and some rules for recalling them when needed. The mind, contrary to Locke’s poetic assertion, must come with some initial furnishings in order for it to be furnished further through experience. While empiricist philosophy flourished in England, nativist philosophy took root in Germany, led by such thinkers as Gottfried Wilhelm von Leibniz (1646–1716) and Immanuel Kant (1724–1804). In his Critique of Pure Reason (1781/1908), Kant distinguished between a priori knowledge, which is built into the human brain and does not have to be learned, and a posteriori knowledge, which one gains from experience in the environment. Without the first, a person could not acquire the second. As an illustration, Kant referred to a child’s learn- ing of language. The specific words and grammar that the child acquires are a posteriori knowledge, but the child’s ability to learn a language at all depends on a priori knowl- edge. The latter includes built-in rules about what to attend to and how to store and organize the verbal sounds that are heard in ways that allow the child eventually to make sense of them. Kant also argued that to make any sense of the physical world, the child must already have, built into its mind, certain fundamental physical concepts, such as the concepts of space and time. Without such concepts, a child would have no capacity for seeing an apple as spherical or Alan Decker / University of California, San Diego for detecting the temporal contiguity of two events. A fun robot that can learn This computer-driven robot, designed by researchers at the University of California, San Diego, can keep track of some of its previous inter- actions with children and incorporate them into its future responses to the children. Such machines can learn only the kinds of information that they are programmed to learn. Similarly, according to nativist philosophers, human learning is limited by the information and operating rules that are genetically programmed into the human brain.
  9. 9. 000-023_CH001_12708_Brochure.qxp 11/11/05 9:56 AM Page 8 8 PART 1 ■ BACKGROU ND TO THE STU DY OF PSYCHOLOGY The Idea That the Machinery of Behavior and Mind Evolved Through Natural Selection Kant understood that the human mind has some innate furnishings, but he had no scientific explanation of how those furnishings could have been built or why they function as they do. That understanding came, at last, in 1859, when the English naturalist Charles Darwin (1809–1882) published The Origin of Species, a book that was destined to revolutionize biology, mark a new age in philosophy, and provide, along with the developments in physiology, a biological grounding for psychology. Natural Selection and the Analysis of the Functions of Behavior 10 <<< Darwin’s fundamental idea (explained much more fully in Chapter 3) was that How did Darwin’s theory of natural selection living things evolve gradually, over generations, by a process of natural selection. offer a scientific foundation for explaining Those individuals whose inherited characteristics are well adapted to their envi- behavior by describing its functions? How did it provide a basis for understanding ronment are more likely to survive and reproduce than are other individuals. At the origin of a priori knowledge? each generation, random changes in the hereditary material produce variations in offspring, and those variations that improve the chance of survival and reproduc- tion are passed from generation to generation in increasing numbers. Because of natural selection, species of plants and animals change gradually over time in ways that allow them to meet the changing demands of their environ- ments. Because of evolution, the innate characteristics of any given species of plant or animal can be examined for the functions they serve in allowing individu- als to survive and reproduce. To understand, for example, why finches have stout beaks and warblers have slender beaks, one must know what foods the birds eat and how they use their beaks to obtain those foods. The same principle that applies to anatomy applies to behavior. Through natural selection, living things have ac- quired instinctive tendencies to behave in ways that promote their survival and re- production. A key word here is function. While physiologists were examining the neural mechanisms of behavior, and empiricist philosophers were analyzing law- ful relationships between behavior and the environment, Darwin was studying the functions of behavior—the ways in which an organism’s behavior helps it to sur- vive and reproduce. Application of Darwin’s Ideas to Psychology In The Origin of Species, Darwin discussed only plants and non-human animals, but in later writings he made it clear that he viewed humans as no exception. We hu- mans also evolved through natural selection, and our anatomy and behavior can be analyzed in the same ways as can those of other living things. In a book entitled The Expression of the Emotions in Man and Animals, Darwin (1872/1965) illustrated how evolutionary thinking can contribute to a scientific un- derstanding of human behavior. He argued that the basic forms of human emo- tional expressions (such as laughing and crying) are inherited, as are those of other animals, and may have evolved because the ability to communicate one’s emo- Granger Collection tions or intentions to others of one’s kind improves one’s chances of survival. Darwin’s work provided psychology with a scientific way of thinking about all the inborn universal tendencies that constitute human nature. The innate mecha- nisms underlying human emotions, drives, perceptual abilities, learning abilities, and capacities for reason came about gradually because they promoted the sur- vival and reproduction of our ancestors. One approach to understanding such char- acteristics is to analyze their evolutionary functions—their ways of promoting Charles Darwin Darwin’s principle of survival and reproduction. evolution by natural selection helped If Kant had been privy to Darwin’s insight, he would have said that the innate provide a scientific footing for psy- furnishings of the mind, which make it possible for children to learn language, to chology. The principle links humans to the rest of the biological world and learn about the physical world, to experience human drives and emotions, and, explains the origin of brain mecha- more generally, to behave as human beings and not as blank sheets of paper, came nisms that promote the individual’s about through the process of natural selection, which gradually built all these ca- survival and reproduction. pacities into the brain’s machinery. Darwin, perhaps more than anyone else,
  10. 10. 000-023_CH001_12708_Brochure.qxp 11/11/05 9:56 AM Page 9 CHAPTER 1 ■ FOU N DATIONS FOR TH E STU DY OF PSYCHOLOGY 9 helped convince the intellectual world that we humans, despite our pretensions, are part of the natural world and can be understood through the methods of sci- ence. In this way he helped make the world ripe for psychology. We have now reached the end of the first section of the chapter, and, before >>> 11 moving on, I want to point out a second feature of the book that is designed to help How can the section review at the end of you study it. At the end of each major section of each chapter is a section review each major section of each chapter be used to guide one’s thought and review that summarizes the section’s main ideas. The chart is organized hierarchically: before going on to the next section? the main idea or topic of the section is at the top, the sub-ideas or subtopics are at the next level down, and specific facts and lines of evidence pertaining to each sub- idea or subtopic fill the lower parts. A good way to review, before going on, is to read each item in the chart and think about it. Start at the top and think about the main idea or purpose of the whole section. How would you explain it to another person? Then go down each column, one by one; think about how the idea or topic heading the column pertains to the larger idea or topic above it and how it is sup- ported or elaborated upon by the more specific statements below it. If you are un- clear about the meaning of any item in the chart, or can’t elaborate on that item in a meaningful way, you may want to read the relevant part of the chapter again be- fore moving on. Another way to review is to look back at the focus questions in the margins and make sure you can answer each of them. Section Review Psychology—the science of behavior and the mind—rests on prior intellectual developments. ▼ ▼ ▼ Physical Causation of Behavior The Role of Experience The Evolutionary Basis of • Descartes’s dualism placed more emphasis on • The British empiricists claimed Mind and Behavior the role of the body than had previous versions that all thought and knowledge • Darwin proposed that natural of dualism. Hobbes’s materialism held that are rooted in sensory experience. selection leads to the evolution behavior is completely a product of the body of behavioral tendencies (as and thus physically caused. • They used the concept of associ- ation by contiguity to explain how well as anatomical changes) • To the degree that behavior and the mind have sensory experience could ulti- that promote survival and repro- a physical basis, they are open to study just mately lead to complex thought. duction. like the rest of the natural world. • Darwin’s thinking led to a focus • In contrast to empiricism, on the functions of behavior. • Nineteenth-century physiological studies of nativism asserts that some reflexes and of localization of function in the knowledge is innate and that • Natural selection also offered a brain demonstrated the applicability of science such knowledge enables learning scientific basis for considering to mental processes and behavior. from experience. nativist views. The Scope of Psychology Psychology is a vast and diverse field of research. Every question about behavior and mental experience that is potentially answerable by scientific means is within its scope. One way to become oriented to this grand science is to preview the vari- ous kinds of explanatory concepts that psychologists use. Varieties of Explanations in Psychology, and Their Application to Sexual Jealousy Psychologists strive to explain mental experiences and behavior. To explain is to identify causes. What causes us to do what we do, feel what we feel, perceive what we perceive, or believe what we believe? What causes us to eat in some conditions and not in others; to cooperate sometimes and to cheat at other times; to feel angry, frightened, happy, or guilty; to dream; to hate or love; to see red as different
  11. 11. 000-023_CH001_12708_Brochure.qxp 11/11/05 9:56 AM Page 10 10 PART 1 ■ BACKGROU ND TO THE STU DY OF PSYCHOLOGY from blue; to remember or forget; to suddenly see so- lutions to problems that we couldn’t see before; to learn our native language so easily when we are very young; to become depressed or anxious? This is a sample of the kinds of questions that psychologists try to answer and that are addressed in this book. The causes of mental experiences and behavior are complex and can be analyzed at various levels. The phrase level of analysis, as used in psychology and other sciences, refers to the level, or type, of causal process that is studied. More specifically, in psychology, a person’s behavior or mental experience can be examined at the neural level (brain as cause), genetic level (genes as cause), evolutionary level (natu- The Kobal Collection ral selection as cause), learning level (the individual’s prior experiences with the environment as cause), cognitive level (the individuals’ knowledge or beliefs as cause), social level (the influence of other people as cause), cultural level (the culture in which the per- Sexual jealousy in humans Like son develops as cause), and developmental level (age-related changes as cause). It is any common human behavioral pre- convenient to group these eight levels of analysis into two categories. The first cat- disposition, sexual jealousy can be egory is biological, and consists of neural, genetic, and evolutionary explanations. studied at the neural, genetic, evolu- The second category is experiential, and consists of learning, cognitive, social, cul- tionary, learning, cognitive, social, cul- tural, and developmental levels of tural, and developmental explanations. You will find many examples of each of analysis. Here the theme of sexual these eight levels of analysis in this book. Now, as an overview, I’ll describe each of jealousy is played out by Rita them very briefly. Hayworth, Tyrone Power, and Anthony Any given type of behavior or mental experience can, in principle, be analyzed Quinn in a scene from the 1941 film at any of the eight levels. To illustrate that point, I will suggest, in the following de- Blood and Sand. scriptions, ways by which each level of analysis can be applied to an understanding of sexual jealousy. One reason for choosing sexual jealousy as the example is that it has not, in fact, been studied very much at most of the levels, so I can describe hypothetical ways of studying it without getting into too much factual detail. For our purposes, sexual jealousy can be defined as the set of emotions and behaviors that result when a person believes that his or her relationship with a sexual part- ner, or a potential sexual partner, is threatened by the partner’s involvement with another person. 12 <<< Explanations That Focus on Biological Processes How do neural, genetic, and evolutionary explanations differ from one another? How Neural Explanations All mental experiences and behavioral acts are products of might each be applied toward an under- the nervous system. One logical route to explanation in psychology, therefore, is to standing of jealousy? try to understand how the nervous system produces the specific type of experience or behavior being studied. Researchers who specialize in this level of explanation are referred to as behavioral neuroscientists. Some behavioral neuroscientists study individual neurons (nerve cells) or small groups of neurons to determine how their characteristics contribute to particular psychological capacities, such as learning. Others map out and study larger brain regions and pathways that are directly involved in some particular category of be- havior or experience, such as speaking grammatically, seeing the shapes of objects, or experiencing an emotion such as fear. Behavioral neuroscientists also study the ways that hormones and drugs act on the brain to alter behavior and experience, either in humans or in non-human animals. To date, no neural studies of jealousy have been conducted with human subjects, but at least one such study has been conducted with macaque monkeys (Rilling & others, 2004). Researchers induced a jealous state in male monkeys by exposing each male to the sight of a female, with which he had previously mated, being courted by another male. During this experience, they measured the animal’s brain activity using a technique called positron emission tomography (PET, described in
  12. 12. 000-023_CH001_12708_Brochure.qxp 11/11/05 9:56 AM Page 11 CHAPTER 1 ■ FOU N DATIONS FOR TH E STU DY OF PSYCHOLOGY 11 Viewing the active brain In recent years the field of behavioral neuro- science has advanced greatly, due in Hoa Qui / Picture Quest part to new techniques for assessing the amount of activity that occurs in specific brain locations as a person performs mental tasks. These neuro- imaging techniques are discussed in Chapter 5. Chapter 5). The result was a preliminary mapping of specific brain areas that be- come especially active during the experience of sexual jealousy in male macaques. A next step, not yet taken, might be for neuroscientists to try to increase or de- crease jealous behavior in monkeys by artificially activating or inactivating those same areas of the brain. They might also examine people who have, through strokes or other accidents, suffered damage to those brain areas to determine if they have any deficits in the experience of jealousy. These are the kinds of tech- niques regularly used by behavioral neuroscientists. Genetic Explanations Genes are the units of heredity that provide the codes for building the entire body, including the brain. Differences among individuals in the genes they inherit can cause differences in the brain and, therefore, differences in mental experiences and behavior. Researchers who attempt to explain psychologi- cal differences among individuals in terms of differences in their genes are called behavioral geneticists. Some behavioral geneticists study non-human animals. They may, for example, deliberately modify animals’ genes to observe the effects on behavior. Others study people. To estimate the extent to which variation among people in some particular trait is the result of variation in genes, researchers might assess the degree to which genetic relatedness between people correlates with their degree of similar- ity in that trait. A finding that close genetic relatives are more similar in the trait than are more distant relatives would suggest that genes contribute to variation in the trait. Behavioral geneticists might also try to identify specific genes that con- tribute to a particular trait by analyzing the DNA (genetic material) of people who differ in that trait. People differ in the degree to which they are prone to sexual jealousy. Some are easily made jealous; others are not. To measure the degree to which such differ- ences are the result of genetic differences, researchers might assess sexual jeal- ousy in twins. If identical twins, who share all their genes with each other, are much more similar in jealousy than are same-sex non-identical twins, who are no more closely related than other siblings, that would indicate that much of the vari- ation among people in sexual jealousy is caused by variation in genes. A next step might be to find out just which genes are involved in these differences and how they act on the brain to influence jealousy. So far, no such studies have been done of sexual jealousy, but you will read later of such studies of intelligence (in Chapter 10), personality traits such as extraversion (in Chapter 15), and predisposi- tions to mental disorders such as schizophrenia and depression (in Chapter 16).
  13. 13. 000-023_CH001_12708_Brochure.qxp 11/11/05 9:56 AM Page 12 12 PART 1 ■ BACKGROU ND TO THE STU DY OF PSYCHOLOGY Duck jealousy Ducks, such as these blue-winged teals, form monogamous pair bonds, at least for the duration of the breeding season. When an intruder encroaches, the member of the pair © Cliff Beittel that is the same sex as the intruder drives the intruder away. Such jealous- like behavior helps to keep the mated pair intact. Evolutionary Explanations All the basic biological machinery underlying behav- ior and mind, coded by genes, is a product of evolution by natural selection. One way to explain universal human characteristics, therefore, is to explain how or why that characteristic came about in evolution. Researchers who specialize in this level of analysis are called evolutionary psychologists. Some evolutionary psychologists are interested in the actual routes by which particular behavioral capacities or tendencies evolved. For instance, researchers studying the evolution of smiling have gained clues about how smiling originated in our ancestors by examining smile-like behaviors in other primates, including chimpanzees (discussed in Chapter 3). Most evolutionary psychologists are inter- ested in identifying the evolutionary functions—that is, the survival or reproductive benefits—of the types of behaviors and mental experiences that they study. In later chapters you will read about evolutionary, functional explanations of many human behavioral tendencies, drives, and emotions. Evolutionary psychologists have examined the forms and consequences of human jealousy in some detail in order to identify its possible benefits for repro- duction (Buss, 2000). Toward the same end, researchers have also examined jealous-like behavior in many other animal species. Such research supports the view that jealousy functions to promote long-term mating bonds. In all animals that form such bonds, behavioral mechanisms (discussed in Chapter 3) have evolved that motivate the mated male or female to actively drive off, or in other ways discourage, competitors for his or her mate. Explanations That Focus on Environmental Experiences, Knowledge, and Development 13 <<< Learning Explanations Essentially all forms of human behavior and mental How do learning and cognitive explana- experience are modifiable by learning; that is, they can be influenced by prior ex- tions differ from each other? How might periences. Prior experiences can affect our emotions, drives, perceptions, each be applied toward an understanding of jealousy? thoughts, skills, and habits. Most psychologists are in one way or another inter- ested in the role that experience plays in shaping the types of behavior that they study. Those who explain behavior most directly in terms of past experiences with the environment refer to themselves as learning psychologists. These specialists might, for example, attempt to explain compulsive gambling in terms of the pat- tern of rewards that the person has experienced in the past while gambling, or might attempt to explain particular fears in terms of previous experiences with the feared objects or situations. They might also conduct research, with animals as well as people, to understand the most efficient ways to acquire new skills (dis- cussed in Chapter 4).
  14. 14. 000-023_CH001_12708_Brochure.qxp 11/11/05 9:56 AM Page 13 CHAPTER 1 ■ FOU N DATIONS FOR TH E STU DY OF PSYCHOLOGY 13 Differences among individuals in jealousy derive partly from genetic differences, but they also derive partly from differences in past experi- ences. Jealous reactions that prove to be effective in obtaining rewards— such as those that succeed in repelling competitors or attracting renewed affection from the beloved—may increase in frequency with experience, and ineffective reactions may decrease. People and animals may also Walter Dawn / Photo Researchers, Inc. learn, through experience, what sorts of cues are potential signs of infi- delity in their mates, and those cues may come to trigger jealous reac- tions. The intensity of sexual jealousy, the specific manner in which it is expressed, and the environmental cues that trigger it can all be influ- enced, in many ways, by learning. Learning psychologists might study all of those effects. Cognitive Explanations The term cognition refers to information in the mind—that is, to information that is somehow stored and activated by the workings of the brain. Such information includes thoughts, beliefs, and all forms of memories. Some information is innate to the human mind, as nativist Rat learning to press a lever To philosophers pointed out, and other information is acquired through learning, as identify basic principles of learning, empiricist philosophers pointed out. Some information is conscious, in the sense some learning psychologists study the processes by which animals learn that the person is aware of it and can describe it, and other information is uncon- simple responses for rewards. This scious but can still influence one’s conscious experiences and behavior. One way to thirsty rat receives a drop of water to explain any behavioral action or mental experience is to relate it to the cognitions drink each time it presses the lever. (items of mental information) that underlie that action or experience. Researchers who specialize in this level of analysis are called cognitive psychologists. You can think of mental information as analogous to the operating rules (soft- ware) and data that are stored in a computer, which influence the way that the com- puter responds to particular forms of input. Cognitive psychologists are interested in specifying, as clearly as possible, the types of mental information that underlie and make possible the behaviors that they study. For instance, a cognitive psychol- ogist who is interested in reasoning might attempt to understand the rules by which people manipulate information in their minds in order to solve particular classes of problems (discussed in Chapter 10). A cognitive psychologist who is interested in racial prejudice might attempt to specify the particular beliefs—including uncon- scious as well as conscious beliefs—that promote prejudiced behavior (discussed in Chapter 13). Cognitive psychologists are also interested in the basic processes by which learned information is stored and organized in the mind, which means that they are particularly interested in memory (discussed in Chapter 9). In general, cognitive psychology differs from the psychology of learning in its focus on the mind. Learning psychologists generally attempt to relate learning ex- periences directly to behavioral changes and are relatively unconcerned with the mental processes that mediate such relationships. To a learning psychologist: expe- rience in the environment leads to change in behavior. To a cognitive psychologist: ex- perience in the environment leads to change in knowledge or beliefs, and that change leads to change in behavior. A cognitive psychologist interested in jealousy would define jealousy first and foremost as a set of beliefs—beliefs about the behavior of one’s beloved and some third party, about the vulnerability of one’s own relationship with the beloved, and about the appropriateness or inappropriateness of possible ways to react. One way to study jealousy, from a cognitive perspective, is to ask people to recall episodes of it from their own lives and to describe the thoughts that went through their minds, the emotions they felt, and the actions they took. Such work reveals that a wide va- riety of thoughts can enter one’s mind in the jealous state, which can lead to actions ranging from romantic expressions of love to murderous violence (Guerrero & oth- ers, 2005). Psychotherapists who use cognitive methods to treat cases of pathologi- cal jealousy try to help their clients change their thought patterns, so they will no longer misperceive every instance of attention that the beloved pays to someone else as a threat to their relationship, and so they will focus on constructive rather than destructive ways of reacting to actual threats (Bishay & others, 1996).
  15. 15. 000-023_CH001_12708_Brochure.qxp 11/11/05 9:56 AM Page 14 14 PART 1 ■ BACKGROU ND TO THE STU DY OF PSYCHOLOGY 14 <<< Social Explanations We humans are, by nature, social animals. We need to co- How do social and cultural explanations operate and get along with others of our species in order to survive and reproduce. differ from each other? How might each of For this reason, our behavior is strongly influenced by our perceptions of others. these be applied toward understanding jealousy? We use others as models of how to behave, and we often strive, consciously or un- consciously, to behave in ways that will lead others to accept us and approve of us. One way to explain mental experiences and behavior, therefore, is to identify how it is influenced by other people or by one’s beliefs about other people (discussed in Chapters 13 and 14). Researchers who specialize in this level of analysis are called social psychologists. According to an often-quoted definition (originally from Allport, 1968), “social psychology is the attempt to understand and explain how the thought, feeling, and behavior of individuals are influenced by the actual, imagined, or implied pres- ence of others.” Social psychologists often explain behavior in terms of conformity to social norms, or obedience to authority, or living up to others’ expectations. A popular term for all such influences is “social pressure.” Social-psychological explanations are often phrased in terms of people’s con- scious or unconscious beliefs about the potential social consequences of acting in a particular way. This means that many social-psychological explanations are also cognitive explanations. Indeed, many modern social psychologists refer to their specialty as social cognition. A social psychologist interested in physical fitness, for example, might attempt to explain how people’s willingness to exercise is influ- enced by their beliefs about others’ fitness efforts and their beliefs about how oth- ers will react to them if they do or do not exercise. A social psychologist interested in jealousy might focus on the norms and beliefs concerning romance, mating, and jealousy that surround and influence the jealous person. How do others react in similar situations? Are the beloved’s flirtations with a third person within or outside the realm of what is considered acceptable by other dating or married couples? Would violent revenge be approved of or disap- proved of by others who are important to the jealous person? Implicitly or explic- itly, the answers to such questions influence the way the jealous person feels and behaves. An understanding of such influences constitutes a social-psychological explanation of the person’s feelings and behavior. Cultural Explanations We can predict some aspects of a person’s behavior by knowing what culture that person grew up in. Cultures vary in language or dialect, in the values and attitudes they foster, and in the kinds of behaviors and emotions they encourage or discourage. Researchers have found consistent cultural differ- ences even in the ways that people perceive and remember aspects of their physi- cal environment (discussed in Chapter 10). Researchers who explain mental experiences and behavior in terms of the culture in which the person developed are called cultural psychologists. Cultural and social psychology are very closely related, but differ in emphasis. While so- cial psychologists emphasize the immediate so- cial influences that act on individuals, cultural © The New Yorker Collection 2005 Marshall Hopkins psychologists strive to characterize entire cul- tures in terms of the typical ways that people from All rights reserved. within them feel, think, and act. While social psy- chologists use concepts such as conformity and obedience to explain an individual’s behavior, cultural psychologists more often refer to the unique history, economy, and religious or philo- sophical traditions of a culture to explain the val- ues, norms, and habits of its people. For example, a cultural psychologist might contend that the frontier history of North America, in which indi- “Mom! Everybody at school says we’re just a bunch of crazy Victorians.” viduals and families often had to struggle on their