HISTORY OF PSYCHOLOGY. THE BIOLOGY OF MIND.
CONSCIOUSNESS AND THE TWO-TRACK MIND.
Psychology’s Roots.
Psychology traces its roots back through recorded history to the writings of many scholars who spent their lives wondering about people—in India, China, the Middle East, and Europe. In their attempt to understand human nature, they looked carefully at how our minds work and how our bodies relate to our minds.
Psychology as a science
The eventual emergence of psychology as a science hinged on advances in other sciences, particularly physiology. Physiology is a branch of biology that studies the functions and parts of living organisms, including humans.
In the 1600s, physiologists were becoming interested in the human brain and its relation to behavior. By the early 1700s, it was discovered that damage to one side of the brain produced a loss of function in the opposite side of the body. By the early 1800s, the idea that different brain areas were related to different behavioral functions was being vigorously debated.
Collectively, the early scientific discoveries made by physiologists were establishing the foundation for an idea that was to prove critical to the emergence of psychology—namely, that scientific methods could be applied to issues of human behavior and thinking.
The Influence of Philosophy and Physiology
The earliest origins of psychology can be traced back several centuries to the writings of the great philosophers. More than two thousand years ago, the Greek philosopher Aristotle wrote extensively about topics like sleep, dreams, the senses, and memory. He also described the traits and dispositions of different animals (Robinson, 1997). Many of Aristotle’s ideas remained influential until the beginnings of modern science in the seventeenth century. At that time, the French philosopher René Descartes (1596–1650) proposed a doctrine called interactive dualism—the idea that mind and brain were separate entities that interact to produce sensations, emotions, and other conscious experiences. Today, psychologists continue to debate the relationship between mental activity and the brain. Philosophers also laid the groundwork for another issue that would become central to psychology—the nature– nurture issue. For centuries, philosophers debated which was more important: the inborn nature of the individual or the environmental influences that nurture the individual. Psychologists continue to focus on this question, which today is usually framed in terms of heredity versus environment. Such philosophical discussions influenced the topics that would be considered in psychology. But the early philosophers could advance the understanding of human behavior only to a certain point. Their methods were limited to intuition, observation, and logic.
With this general understanding of science, we turn to the origins of psychology. The subject matter of psychology has interested some of the greatest thinkers since classical antiquity, but it became a formal science only recently. It emerged as a separate discipline, with its own contents and methods, approximately a century ago, and this event was significantly stimulated by developments in philosophy, biology, and physics.
Early Contributions
The philosophical background came first, traceable even to Aristotle, who disagreed with Plato, his teacher. Aristotle said that all knowledge is obtained through experience; what we know depends solely on our experience in the world.
Empiricism in Philosophy This view, certainly not startling today, lay dormant for hundreds of years and was considered radical even as late as the seventeenth century. Eventually, it came to be regarded with favor, especially by nineteenth-century educators, who emphasized the importance of life experiences inside and outside the classroom. Today the word empiricism, coming from the Greek word for experience, means that we know through direct experience. Knowledge is not innate, as Plato had suggested, but acquired through the senses during our lifetime.
This doctrine had important implications for science. Observe the event, such as a confrontation among three Christs, and let experience tell the story. Bringing the three Christs together was an empirical test of Voltaire's hypothesis. Voltaire had only heard about the incident with the deranged man, which allegedly took place decades earlier. Had it really happened? If so, were the details correct? Or was the report based on what someone thought would occur? Empiricism is of central importance in all science. The most substantial test of a hypothesis is through direct observation.
Darwinian Influence One person who made careful observations was Charles Darwin. Just before the founding of psychology he completed a voyage around the world and described 'what he had observed. Specifically, Darwin noted the wide variations in structure and behavior among the species and observed the struggle for existence among all organisms. Those that survive and therefore reproduce, he decided, are those most adapted to their environment. The poorly adapted perish and produce no offspring. Through this process of natural selection, continued over millions of years, distinctly different organisms appeared.
Darwin's theory of evolution, which states that any plant or animal species developed through modifications of preexisting species, was highly controversial, but it had a tremendous effect on the study of human behavior and experience. It prompted all sorts of speculation about a continuity from the animal to the human mind and about the nature of animal mental life (Darwin, 1859, 1965). Furthermore, the idea of animal instincts, which was well accepted, led to speculation about human instincts and to the study of human motivation.
It should be understood that the theory of evolution, although popularly attributed to Darwin, did not originate exclusively with him. The idea that human beings are ultimately descended from animals is ancient, appearing in early Greek philosophy. Darwin's contribution illustrates the scientific process. He gathered more facts, made an interpretation about them, and then published a research report, The Origin of the Species. The result was a more empirical basis for the concept of evolution and further interest in understanding human and animal behavior and experience. Experimental Methods Just one year after Darwin's book appeared, Gustav T. Fechner, a physicist, published a book written from an entirely different perspective. The basic idea occurred to him while he was lying in bed one October morning, thinking about how he could measure mental reactions. He would present some stimulus in a carefully measured amount, such as a tone of low intensity, and then note the listener's experience. Could the listener hear it? This procedure then would be repeated with another tone. Could the new tone be perceived? Was it different from the preceding one? With methods of this sort, adapted from physics, Fechner could study the relations between physical stimuli and sensory experience.
Fechner elaborated on this approach, tested it, and published his findings under the title Elements of Psychophysics. The significance of this work lay in its exact procedures for studying human experience. It showed that mental phenomena could be quantified by using methods from physics, and today's psychophysics is the study of relationships between sensory experiences and the characteristics of stimuli that produce them.
Fechner's work provided an important contrast to Darwin's. Making observations in the natural environment, like Darwin did, is called the descriptive or naturalistic method. In Fechner's approach the scientist manipulates the environment while making observations. The investigator causes certain events to happen and measures the result. This procedure of manipulating and controlling aspects of the environment is called the experimental method, for it allows the investigator to study cause-and-effect relations.
Both approaches have assets and limitations, and both have contributed significantly to our understanding of mental life and behavior. For example, Philippe Pinel, the French physician, first removed restraints from asylum inmates after naturalistic observation; he had observed the positive effects of freedom on emotionally disturbed people. The early work in America was more experimental, as physicians tried bloodletting, inducing "vomits," and forcing more blood into the brain by spinning people in a centrifugal bed, all without significant success.
Psychological Science Development.
Wilhelm Wundt - The Founder of Psychology
By the second half of the 1800s, the stage had been set for the emergence of psychology as a distinct scientific discipline. The leading proponent of this idea was a German physiologist named Wilhelm Wundt.
Wundt used scientific methods to study fundamental psychological processes, such as mental reaction times in response to visual or auditory stimuli. For example,Wundt tried to measure precisely how long it took a person to consciously detect the sight and sound of a bell being struck.
A major turning point in psychology occurred in 1874, when Wundt published his landmark text, Principles of Physiological Psychology.
In this book, Wundt outlined the connections between physiology and psychology. He also promoted his belief that psychology should be established as a separate scientific discipline that would use experimental methods to study mental processes
A few years later, in 1879, Wundt realized that goal when he opened the first psychology research laboratory at the University of Leipzig. Many regard this event as marking the formal beginning of psychology as an experimental science.
Wundt defined psychology as the study of consciousness and emphasized the use of experimental methods to study and measure consciousness. Until he died in 1920, Wundt exerted a strong influence on the development of psychology as a science. Two hundred students from around the world, including many from the United States, traveled to Leipzig to earn doctorates in experimental psychology under Wundt’s direction. Over the years, some 17,000 students attended Wundt’s afternoon lectures on general psychology, which often included demonstrations of devices he had developed to measure mental processes (Blumenthal, 1998).
Wundt and Experimentalism
The event usually considered to mark the formal beginning of psychology as a science occurred in Germany in the 1870s. Wilhelm Wundt, at the University of Leipzig, established a laboratory for research in psychology, and in 1879 a doctoral candidate completed the first independent research study. That year is regarded as the beginning of modern psychology, and Wundt, through his early handbook on experimental psychology and his first laboratory, is considered the father of scientific psychology.
Wundt's Laboratory As a philosopher, Wundt had noted the fruitfulness of the experimental method in other fields and, as a physiologist, he had engaged in laboratory research himself. His first investigation was an examination of the salt content of his own urine, and the second was a paper on the vivisection of the vagus nerve. He began in psychology by adapting apparatus from physics and physiology, but soon he was encountering new problems and devising new apparatus to measure stimuli and responses. What impressed Wundt most were the possibilities for discovering lawful relations between intensities of stimuli and the experiences that they aroused.
These early findings appeared to refute the widely held view that consciousness could not be measured. It seemed to Wundt that the mind, or conscious experience, which he regarded as synonymous, could indeed be measured. Investigators in his laboratory studied all kinds of mental conditions, including reaction time, attention, dizziness, and fatigue.
Wundt's Psychology Psychology for Wundt was the study of immediate experience, and the goal of the new science was to develop techniques for understanding and measuring it. Anything that did not lead in this direction was thought to be outside psychology's sphere of interest. Most of Wundt's data were therefore subjective, evident only to the experiencing individual, and there was great difficulty in establishing verifiable, repeatable observations. His approach included no interest in children or animals, who could not give accurate reports of their experiences, and individual differences among adults were ignored. He would have displayed little interest in the three Christs, who might give unreliable reports. Also, they presented a problem of practical interest, rather than academic concern.
Despite these limitations, Wundt's approach attracted a large number of disciples, and his psychology was referred to as structuralism or structural psychology.
This name arose because it was believed that the structure of mental life could be disclosed in this way. Just as a chemist analyzes matter into its elements, the simplest units or elements of mental life might be identified. Strictly speaking, Wundt was not a structuralist himself, but his efforts spawned this laboratory work, for which no comparable opportunity existed in Europe and America. Prominent psychologists were trained in his laboratory, and his work continues to be a topic of interest.
Edward B. Titchener. Structuralism
One of Wundt’s most devoted students was a young Englishman named Edward B. Titchener. After earning his psychology doctorate in Wundt’s laboratory in 1892, Titchener accepted a position at Cornell University in Ithaca, New York.
There he established a psychology laboratory that ultimately spanned 26 rooms. Titchener eventually departed from Wundt’s position and developed his own ideas on the nature of psychology. Titchener’s approach, called structuralism, became the first major school of thought in psychology. Structuralism held that even our most complex conscious experiences could be broken down into elemental structures, or component parts, of sensations and feelings. To identify these structures of conscious thought, Titchener trained subjects in a procedure called introspection. The subjects would view a simple stimulus, such as a book, and then try to reconstruct their sensations and feelings immediately after viewing it. (In psychology, a stimulus is anything perceptible to the senses, such as a sight, sound, smell, touch or taste. They might first report on the colors they saw, then the smells, and so on, in the attempt to create a total description of their conscious experience (Tweney, 1997). In addition to being distinguished as the first school of thought in early psychology, Titchener’s structuralism holds the dubious distinction of being the first school to disappear.With Titchener’s death in 1927, structuralism as an influential school of thought in psychology essentially ended. But even before Titchener’s death, structuralism was often criticized for relying too heavily on the method of introspection.
Titchener eventually departed from Wundt’s position and developed his own ideas on the nature of psychology. Titchener’s approach, called structuralism, became the first major school of thought in psychology.
Structuralism held that even our most complex conscious experiences could be broken down into elemental structures, or component parts, of sensations and feelings. To identify these structures of conscious thought, Titchener trained subjects in a procedure called introspection. The subjects would view a simple stimulus, such as a book, and then try to reconstruct their sensations and feelings immediately after viewing it. (In psychology, a stimulus is anything perceptible to the senses, such as a sight, sound, smell, touch or taste. They might first report on the colors they saw, then the smells, and so on, in the attempt to create a total description of their conscious experience.
Structuralism - early school of psychology that emphasized studying the most basic components, or structures, of conscious experiences.
As noted repeatedly by Wundt and others, introspection had significant limitations (Blumenthal, 1998). First, introspection was an unreliable method of investigation. Different subjects often provided very different introspective reports about the same stimulus. Even subjects well trained in introspection varied in their responses to the same stimulus from trial to trial. Second, introspection could not be used to study children or animals. Third, complex topics, such as learning, development, mental disorders, and personality, could not be investigated using introspection. In the end, the methods and goals of structuralism were simply too limited to accommodate the rapidly expanding interests of the field of psychology.
W. James and Functionalism
One early visitor to the site of Wundt's work was William James, a young American suffering from some maladjustment himself. Bright, personable, and witty, he had received an excellent education in the United States and Europe, but he could not decide what he wanted to do with his life. College students today perhaps can appreciate his predicament.
James's Writings After his short visit to Germany, when he was physically and emotionally upset with "finding himself," James accepted a modest teaching position in physiology, beginning as an unknown except for the growing fame of his younger brother, Henry. Soon, however, William James shifted from physiology to psychology, and in 1875, four years before the official date associated with Wundt's laboratory, he developed his own. However, it was used only for demonstrations, rather than research, and therefore the credit for founding scientific psychology generally is accorded to Wundt .
More important to psychology were James's accomplishments as a writer and teacher. When his two-volume textbook entitled Principles of Psychology appeared in 1890, it earned him an international reputation, not only for its science but also for its literary style. Afterward, James wrote the "Jimmy," a shorter version of his textbook.
Largely because of these books, William James is recognized as the father of American psychology.
James's Psychology James disagreed with Wundt's psychology, advocating a broader approach. Called functionalism, or functional psychology, it emphasized the functions of mental life rather than the contents. Wundt had tried to measure conscious human experience, but James thought that consciousness should be studied from the standpoint of how it is related to adaptation. Wundt asked, "What is mind?" James asked, "What is mind for?" Wundt, if he studied the three Christs at all, would have attempted to understand and measure their conscious experience, whereas James would have been more interested in finding out how their delusional thinking apparently helped them adapt to their environment. In short, functionalists were more interested in what mental life does than in what it is, a natural view for practical-minded Americans.
In 1906, the year before his retirement, William James became more involved in the problem of mental disorders. A young man sent him a manuscript describing his experience during a mental breakdown. James was immediately enthusiastic, agreed to write a preface, and predicted that Clifford Beers's story, The Mind That Found Itself, would be of absorbing interest to the psychologist and layperson alike. He was right, and with James's further encouragement, Beers founded the National Committee for Mental Hygiene, beginning that movement in this country and with it a deepening interest in abnormal and clinical psychology.
Through James's work, psychology gained much of its identity and gradually broadened in scope, for he wrote on such diverse topics as habit, reasoning, instinct, emotion, education, and hypnotism, as well as mental disorders. Modern psychology is broadly functional, including all aspects of mental life and behavior, thanks in no small way to James's efforts. In turn, James found his own identity through his work in psychology. Looking backward, he once wryly remarked that the first lecture he heard in psychology was the one that he gave himself.
James had first become intrigued by the emerging science of psychology after reading one of Wundt’s articles, entitled “Recent Advances in the Field of Physiological Psychology,” in the late 1860s.
In the early 1870s, James began teaching a physiology and anatomy class at Harvard University. An intense, enthusiastic teacher, James was prone to changing the subject matter of his classes as his own interests changed
Gradually, his lectures came to focus more on psychology than on physiology. By the late 1870s, James was teaching classes devoted exclusively to the topic of psychology.
James’s ideas became the basis of another early school of psychology, called functionalism, which stressed studying the adaptive and practical functions of human behavior.
Functionalism stressed the importance of how behavior functions to allow people and animals to adapt to their environments. Unlike structuralists, functionalists did not limit their methods to introspection. They expanded the scope of psychology research to include direct observation of living creatures in natural settings. They also examined how psychology could be applied to areas such as education, child rearing, and the work environment.
Both the structuralists and the functionalists thought that psychology should focus on the study of conscious experiences. But the functionalists had very different ideas about the nature of consciousness and how it should be studied. Rather than trying to identify the essential structures of consciousness at a given moment, James saw consciousness as an ongoing stream of mental activity that shifts and changes.
By the time Titchener arrived at Cornell University, psychology was already well established in the United States. The main proponent of American psychology was one of Harvard’s most outstanding teachers—William James. James had first become intrigued by the emerging science of psychology after reading one of Wundt’s articles, entitled “Recent Advances in the Field of Physiological Psychology,” in the late 1860s.
In the early 1870s, James began teaching a physiology and anatomy class at Harvard University. An intense, enthusiastic teacher, James was prone to changing the subject matter of his classes as his own interests changed (B. Ross, 1991). Gradually, his lectures came to focus more on psychology than on physiology. By the late 1870s, James was teaching classes devoted exclusively to the topic of psychology.
At about the same time, James began writing a comprehensive textbook of psychology, a task that would take him more than a decade. James’s Principles of Psychology was finally published in two volumes in 1890. Despite its length of more than 1,400 pages, Principles of Psychology quickly became the leading psychology textbook. In it, James discussed such diverse topics as brain function, habit, memory, sensation, perception, and emotion. James’s dynamic views had an enormous impact on the development of psychology in the United States (Bjork, 1997b).
James’s ideas became the basis for a new school of psychology, called functionalism. Functionalism stressed the importance of how behavior functions to allow people and animals to adapt to their environments. Unlike structuralists, functionalists did not limit their methods to introspection. They expanded the scope of psychology research to include direct observation of living creatures in natural settings. They also examined how psychology could be applied to areas such as education, child rearing, and the work environment. Both the structuralists and the functionalists thought that psychology should focus on the study of conscious experiences. But the functionalists had very different ideas about the nature of consciousness and how it should be studied. Rather than trying to identify the essential structures of consciousness at a given moment, James saw consciousness as an ongoing stream of mental activity that shifts and changes. As James wrote in Talks to Teachers (1899): Now the immediate fact which psychology, the science of mind, has to study is also the most general fact. It is the fact that in each of us, when awake (and often when asleep) some kind of consciousness, is always going on.
There is a stream, a succession of states, or waves, or fields (or whatever you please to call them), of knowledge, of feeling, of desire, of deliberation, etc., that constantly pass and repass, and that constitute our inner life. The existence of this is the primal fact, [and] the nature and origin of it form the essential problem, of our science. Like structuralism, functionalism no longer exists as a distinct school of thought in contemporary psychology. Nevertheless, functionalism’s twin themes of the importance of the adaptive role of behavior and the application of psychology to enhance human behavior continue to be evident in modern psychology (D. N. Robinson, 1993).
William James and His Students
Like Wundt, James profoundly influenced psychology through his students, many of whom became prominent American psychologists. Two of James’s most notable students were G. Stanley Hall and Mary Whiton Calkins. In 1878, G. Stanley Hall received the first Ph.D. in psychology awarded in the United States. Hall founded the first psychology research laboratory in the United States at Johns Hopkins University in 1883. He also began publishing the American Journal of Psychology, the first U.S. journal devoted to psychology. Most important, in 1892, Hall founded the American Psychological Association and was elected its first president (Dewsbury, 2000). Today, the American Psychological Association (APA) is the world’s largest professional organization of psychologists, with more than 150,000 members. In 1890, Mary Whiton Calkins was assigned the task of teaching experimental psychology at a new women’s college—Wellesley College. Calkins studied with James at nearby Harvard University. She completed all the requirements for a Ph.D. in psychology.
However, Harvard refused to grant her the Ph.D. degree because she was a woman and at the time Harvard was not a coeducational institution. Although never awarded the degree she had earned, Calkins made several notable contributions to psychology (Stevens & Gardner, 1982). She conducted research in many areas, including dreams, memory, and personality. In 1891, she established a psychological laboratory at Wellesley College. At the turn of the century, she wrote a well-received textbook, titled Introduction to Psychology.
In 1905, Calkins was elected president of the American Psychological Association— the first woman, but not the last, to hold that position. Just for the record, the first American woman to earn an official Ph.D. in psychology was Margaret Floy Washburn.
Washburn was Edward Titchener’s first doctoral student at Cornell University. She strongly advocated the scientific study of the mental processes of different animal species. In 1908, she published an influential text, titled The Animal Mind. Her book summarized research on sensation, perception, learning, and other “inner experiences” of different animal species. In 1921, Washburn became the second woman elected president of the American Psychological Association (Carpenter, 1997).
Sigmund Freud. Psychoanalysis
In Vienna, Austria, a physician named Sigmund Freud was developing an intriguing theory of personality based on uncovering causes of behavior that were unconscious, or hidden from the person’s conscious awareness.
Freud’s school of psychological thought, called psychoanalysis, emphasized the role of unconscious conflicts in determining behavior and personality. Freud’s psychoanalytic theory of personality and behavior was based largely on his work with his patients and on insights derived from self-analysis.
Freud believed that human behavior was motivated by unconscious conflicts that were almost always sexual or aggressive in nature. Past experiences, especially childhood experiences, were thought to be critical in the formation of adult personality and behavior. According to Freud (1904), glimpses of these unconscious impulses are revealed in everyday life in dreams, memory blocks, slips of the tongue, and spontaneous humor. Freud believed that when unconscious conflicts became extreme, psychological disorders could result.
Wundt, James, and other early psychologists emphasized the study of conscious experiences. But at the turn of the century, new approaches challenged the principles of both structuralism and functionalism. In Vienna, Austria, a physician named Sigmund Freud was developing an intriguing theory of personality based on uncovering causes of behavior that were unconscious, or hidden from the person’s conscious awareness. Freud’s school of psychological thought, called psychoanalysis, emphasized the role of unconscious conflicts in determining behavior and personality.
Freud’s psychoanalytic theory of personality and behavior was based largely on his work with his patients and on insights derived from self-analysis. Freud believed that human behavior was motivated by unconscious conflicts that were almost always sexual or aggressive in nature. Past experiences, especially childhood experiences, were thought to be critical in the formation of adult personality and behavior. Freud’s psychoanalytic theory of personality also provided the basis for a distinct form of psychotherapy. Many of the fundamental ideas of psychoanalysis continue to influence psychologists and other professionals in the mental health field.
John B. Watson. Behaviorism
The course of psychology changed dramatically in the early 1900s when another approach, called behaviorism, emerged as a dominating force. Behaviorism rejected the emphasis on consciousness promoted by structuralism and functionalism. It also flatly rejected Freudian notions about unconscious influences. Instead, behaviorism contended that psychology should focus its scientific investigations strictly on overt behavior—observable behaviors that could be objectively measured and verified.
Behaviorism is yet another example of the influence of physiology on psychology. Behaviorism grew out of the pioneering work of a Russian physiologist named Ivan Pavlov.
Pavlov demonstrated that dogs could learn to associate a neutral stimulus, such as the sound of a bell, with an automatic behavior, such as reflexively salivating to food. Once an association between the sound of the bell and the food was formed, the sound of the bell alone would trigger the salivation reflex in the dog. Pavlov enthusiastically believed he had discovered the mechanism by which all behaviors were learned.
In the United States, a young, dynamic psychologist named John B. Watson shared Pavlov’s enthusiasm.
Watson (1913) championed behaviorism as a new school of psychology. Structuralism was still an influential perspective, but Watson strongly objected to both its method of introspection and its focus on conscious mental processes. As Watson (1924) wrote in his classic book, Behaviorism: Behaviorism, on the contrary, holds that the subject matter of human psychology is the behavior of the human being. Behaviorism claims that consciousness is neither a definite nor a usable concept. The behaviorist, who has been trained always as an experimentalist, holds, further, that belief in the existence of consciousness goes back to the ancient days of superstition and magic.
The influence of behaviorism on American psychology was enormous. The goal of the behaviorists was to discover the fundamental principles of learning—how behavior is acquired and modified in response to environmental influences. For the most part, the behaviorists studied animal behavior under carefully controlled laboratory conditions. Although Watson left academic psychology in the early 1920s, behaviorism was later championed by an equally forceful proponent—the famous American psychologist B. F. Skinner.
Like Watson, Skinner believed that psychology should restrict itself to studying outwardly observable behaviors that could be measured and verified. In compelling experimental demonstrations, Skinner systematically used reinforcement or punishment to shape the behavior of rats and pigeons.
Between Watson and Skinner, behaviorism dominated American psychology for almost half a century. During that time, the study of conscious experiences was largely ignored as a topic in psychology.
Carl Rogers. Humanistic Psychology
For several decades, behaviorism and psychoanalysis were the perspectives that most influenced the thinking of American psychologists. In the 1950s, a new school of thought emerged, called humanistic psychology. Because humanistic psychology was distinctly different from both psychoanalysis and behaviorism, it was sometimes referred to as the “third force” in American psychology.
Humanistic psychology was largely founded by American psychologist Carl Rogers. Like Freud, Rogers was influenced by his experiences with his psychotherapy clients. However, rather than emphasizing unconscious conflicts, Rogers emphasized the conscious experiences of his patients, including each person’s unique potential for psychological growth and self-direction. In contrast to the behaviorists, who saw human behavior as being shaped and maintained by external causes, Rogers emphasized self-determination, free will, and the importance of choice in human behavior (Bozarth & others, 2002).
Abraham Maslow was another advocate of humanistic psychology. Maslow developed a theory of motivation that emphasized psychological growth. Like psychoanalysis, humanistic psychology included not only influential theories of personality but also a form of psychotherapy, which we’ll discuss in later chapters.
Each of the schools that we’ve described had an impact on the topics and methods of psychological research.
From the founding of Wundt’s laboratory in 1879, psychology has evolved to its current status as a dynamic and multidimensional science.
The ideas of Carl Rogers have been particularly influential in modern psychotherapy.
Abraham Maslow’s theory of motivation emphasized the importance of psychological growth.
By briefly stepping backward in time, you’ve seen how the debates among the key thinkers in psychology’s history shaped the development of psychology as a whole. Each of the schools that we’ve described had an impact on the topics and methods of psychological research. As you’ll see throughout this textbook, that impact has been a lasting one.
From the founding of Wundt’s laboratory in 1879, psychology has evolved to its current status as a dynamic and multidimensional science. In the next section, we’ll touch on some of the more recent developments in psychology’s evolution. We’ll also explore the diversity that characterizes contemporary psychology.
However, rather than emphasizing unconscious conflicts, Rogers emphasized the conscious experiences of his patients, including each person’s unique potential for psychological growth and self-direction.
In contrast to the behaviorists, who saw human behavior as being shaped and maintained by external causes, Rogers emphasized self-determination, free will, and the importance of choice in human behaviour.
After beginning as a “science of mental life,” psychology evolved in the 1920s into a “science of observable behavior.” After rediscovering the mind in the 1960s, psychology now views itself as a “science of behavior and mental processes.” Psychology is growing and globalizing, as psychologists in 69 countries around the world work, teach, and do research.
Contemporary Psychology.
Psychology’s Big Issues
Psychologists wrestle with several recurring issues. One of these is stability and change over our lifetimes. Another is whether we are consistently rational or sporadically irrational. But the biggest and most enduring issue continues the debate of the early philosophers: the relative influences of nature (genes) and nurture (all other influences, from conception to death). In most cases, the debate is no debate: Every psychological event is simultaneously a biological event.
Psychology’s Perspectives
Psychologists view behavior and mental processes from various perspectives. These viewpoints are complementary, not contradictory, and each offers useful insights in the study of behavior and mental processes.
Current perspectives in psychology
We have examined the nature of science, noting the assumptions of orderliness and limited causality, and we have described the scientific attitude as one of demanding evidence. In addition, we have defined psychology as the scientific study of behavior and experience. Its founding was prompted by developments in philosophy, biology, and physics, and Wilhelm Wundt and William James played significant roles in this regard. We now turn to consider contemporary psychology, noting the different viewpoints in the field today.
We have seen, as well, that no significant progress was made with the three Christs through the daily discussions. Each man defended himself against the others in habitual ways.
Clyde claimed that his companions were dead. "They are not really alive. The machines in them are talking. Take the machines out of them and they won't talk anything." When asked where such a machine was located, Clyde pointed to the right side of Joseph's stomach. Joseph unbuttoned his shirt and Clyde felt for the machine. "It isn't there," he announced. "It must have slipped down where you can't feel it." According to Joseph, the others were crazy. "I'm the only God," he said. "Clyde and Rex are patients in a mental hospital and their being patients proves they are insane."
Rex, as Leon sometimes preferred to be called, defended himself in several ways, chiefly by shifting the meaning of the words Jesus Christ and by suggesting that his bunk mates were only instrumental gods. During the research project, he changed his name several times. "It so happens," he stated resolutely, "that my birth certificate says I am Dr. Domino Dominorum et Rex Rexarum, Simplis Christianus Pueris Mentalis Doktor." This Latin meant that he was Lord of Lords and King of Kings, Simple Christian Boy Psychiatrist. He added, "It also says on my birth certificate that I am the reincarnation of Jesus Christ of Nazareth."
With this resistance it seemed clear that a more direct confrontation would be necessary, and so it was arranged to shift the control of the daily meetings from the research team to the men themselves. Each man would become chairman for a day, responsible for announcing the meeting, selecting a topic, choosing a song for opening and closing the session, and signing the register. Joseph was most enthusiastic and Leon most doubtful. "Truth is the chairman," he insisted. But the rotating pattern became well established, and soon some minor alterations in identity took place (Rokeach, 1981).
"A patient in the hospital where I work believed he was G-O-D, busied himself with arrangements for a trip to the Vatican, and generally attempted to operate as a supreme being. One of the aides grew increasingly frustrated with the patient's insistence and decided to tell him that he was the ninth Christ he had met in two years. He also allowed a second patient, who had at one time believed himself to be God, to tell the new patient how crazy an idea it was. But nothing denied the delusions of this patient. With each confrontation he became increasingly angry and irrational.
Diversity of Interests
This research with the three Christs illustrates two different aims in modern psychology. For most scientists, the ultimate aim is to increase our understanding of ourselves and the world in which we live. The goal is to find out about things. But since our earliest existence human beings have also struggled to improve the conditions of life. The aim here, achieved through greater understanding, is the betterment of humankind. Through science we seek both light and fruit. "It is not cant to put truth before comfort," said Lord Adrian, "but most of us would like both if we can get them." Both aims are found in psychology, and they are referred to as basic research and applied psychology, respectively. To some degree they are expressed in the differences between structuralism, as it evolved from Wundt's efforts at understanding the mind, and James's functionalism, concerned with more practical questions.
Basic Research Psychologists who perform scientific studies for the purpose of acquiring further knowledge are said to be involved in basic research. Their purpose is to obtain and disseminate information on human and animal behavior and experience. Often found in college and university settings, these psychologists conduct most of the investigations that have led to the body of knowledge now called psychology. They also work in clinics, business, and government agencies, for the line between light and fruit is partly arbitrary. With the three Christs, the overall aim in basic research was to discover more about the nature of beliefs, especially the process by which delusional beliefs might be changed.
Psychologists' efforts in basic research emphasize the central theme of this chapter and indeed of this book as a whole. An intricate web of related influences underlies the human condition. Many different factors are usually involved in any given response, a condition which we have described as the multiple basis of behavior. Psychologists in basic research are concerned with identifying these multiple factors and showing their interdependence.
Psychology usually does not provide easy generalizations about others' behavior or simple solutions to one's problems. In behavioral science, few one-to-one relationships are observed. It might be said, for example, that Joseph became disturbed because of his cruel and quick-tempered father, who gave him a woman's name in real life and once in a rage threw him on the floor. But among Joseph's siblings there is no history of any mental disorder. Joseph's father is not the sole cause of his disorder, and he may not be involved in any significant way.
Applied Psychology The work of psychology includes more than research, writing, and teaching. Others in the field are less concerned with developing hew knowledge than with solving practical problems, and these efforts are called applied psychology. The aim is to apply, rather than discover, psychological principles, but again the question is not an either-or issue. Applied psychologists sometimes engage in research, but more often they administer mental tests, design equipment, assist with childrearing, provide therapy, develop educational methods, and consult in law, business, education, medicine, government, and so forth. The staff members who provided therapy for the three Christs generally would be regarded as applied psychologists, whereas the investigators concerned with belief systems would be engaged in basic research.
Applied psychology is sometimes misunderstood, especially in fields directly concerning the public. Clinical psychology and psychiatry, for example, are both concerned with the alleviation of mental disorders. But the former is a subspecialty within psychology, involving all forms of human behavior and experience. Psychologists are trained in research and in the administration of psychological tests. The latter is a subspecialty within medicine, concerned with physical health. Psychiatrists are especially qualified in the prescription of drugs. Professionals from these two fields often work together, providing diagnosis and remedial services, but clinical psychology and psychiatry constitute only a small overlap between two broad fields.
Numerous areas of applied psychology are considered throughout this book, including legal psychology, medical psychology, environmental psychology, and educational psychology. Psychology in the United States today is a diverse enterprise with forty different specialties, as determined by the divisions of the American Psychological Association, the major organization for psychologists in this country. Since 1920 this association has grown in membership sixty-five times faster than the general population.
Confronted with this spectrum of topics in a rapidly growing field, you perhaps have been impressed with the task of mastering them. On this basis you may wish to review the methods and study aids in this book, indicated in the prologue, and to make use of the glossary, in the back of the book.
Psychology’s Subfields.
Psychology’s subfields encompass basic research (often done by biological, developmental, cognitive, personality, and social psychologists), applied research (sometimes conducted by industrial/organizational psychologists), and clinical applications. Psychology’s methods and findings aid other disciplines, and they contribute to the growing knowledge base we apply in our everyday lives.
Models of Psychology
As seen in the efforts of Wundt and James, a new science often develops competing theories and positions. Investigators use various ways of approaching the field, and at some point certain ideas tend to take a dominant position. Wundt's approach was extremely influential for a few decades, and then it disappeared rapidly from the scene. When a certain perspective becomes dominant in this field, it is often called a model or system of psychology, for it guides research and theory. A model in many respects defines the field of inquiry for certain scientists, identifying the problems to be studied and the methods for research. Science, on this basis, does not necessarily progress by the mere accumulation of facts but rather through changes in perspective brought about by new models. A particular set of ideas can attract a large, enduring group of adherents if it is sufficiently open-ended to indicate all sorts of problems for the scientists to pursue.
Psychology was developing in this way in the early decades of the twentieth century, and even today there are distinctly different perspectives, just as there are different systems in politics, economics, education, and religion. No one perspective can include all the facts, and each of us, in tutored or untutored ways, has his or her own favored view of humanity. We now turn to the most dominant views in psychology, which typically have arisen under the influence of one or a few individuals.
Ethical issues in psychology
Modern psychology is based on the same assumptions and attitudes that are found in all scientific inquiry, and it incorporates a variety of perspectives within the field, as well as the different goals of basic research and applied psychology. To conclude this chapter, which has emphasized the role of research in the founding of psychology, we consider some ethical issues in research and in everyday life.
EXPERIMENTAL METHOD AND STATISTICAL REASONING IN PSYCHOLOGY
The Need for Psychological Science
The Scientific Attitude.
Scientific inquiry begins with an attitude—a curious eagerness to skeptically scrutinize competing ideas and an open-minded humility before nature. Putting ideas, even crazy-sounding ideas, to the test helps us winnow sense from nonsense. The curiosity that drives us to test ideas and to expose their underlying assumptions carries into everyday life as critical thinking.
Research stimulates the construction of theories, which organize observations and imply predictive hypotheses. These hypotheses (predictions) are then tested to validate and refine the theory and to suggest practical applications.
Critical Thinking.
Many issues in contemporary psychology are far from being settled. And although research findings may have been arrived at in a very objective manner, the interpretation of what findings mean and how they should be applied can be a matter of considerable debate. In short, there is a subjective side to any science, but subjectivity is especially prominent in discussions of psychological research because psychology tackles topics and issues that concern people from all walks of life.
As you look at the evidence that psychology has to offer on many topics, we want to encourage you to engage in critical thinking. In general, critical thinking refers to actively questioning statements rather than blindly accepting them. More precisely, we define critical thinking as the active process of:
1)Trying to minimize the influence of preconceptions and biases while rationally evaluating evidence.
2) Determining the conclusions that can be drawn from the evidence.
3)Considering alternative explanations.
What are the key attitudes and mental skills that characterize critical thinking?
1. The critical thinker can assume other perspectives. Critical thinkers are not imprisoned by their own points of view. Nor are they limited in their capacity to imagine life experiences and perspectives that are fundamentally different from their own. Rather, the critical thinker strives to understand and evaluate issues from many different angles.
2. The critical thinker is aware of biases and assumptions. In evaluating evidence and ideas, critical thinkers strive to identify the biases and assumptions that are inherent in any argument. Critical thinkers also try to identify and minimize the influence of their own biases.
3. The critical thinker is flexible yet maintains an attitude of healthy skepticism. Critical thinkers are open to new information, ideas, and claims. They genuinely consider alternative explanations and possibilities. However, this open-mindedness is tempered by a healthy sense of skepticism. The critical thinker consistently asks, “What evidence supports this claim?”
4. The critical thinker engages in reflective thinking. Critical thinkers avoid knee-jerk responses. Instead, critical thinkers are reflective. Most complex issues are unlikely to have a simple resolution. Therefore, critical thinkers resist the temptation to sidestep complexity by boiling an issue down to an either/or, yes/no kind of proposition. Instead, the critical thinker expects and accepts complexity.
5. The critical thinker scrutinizes the evidence before drawing conclusions. Critical thinkers strive to weigh all the available evidence before arriving at conclusions. And, in evaluating evidence, critical thinkers distinguish between empirical evidence and opinions based on feelings or personal experience. As you can see, critical thinking is not a single skill, but rather a set of attitudes and thinking skills. As is true with any set of skills, you can get better at these skills with practice. That’s one reason we’ve included Critical Thinking boxes in many chapters of this text. You’ll discover that these Critical Thinking boxes do not follow a rigid formula but are very diverse. Some will challenge your preconceptions about certain topics. Others will invite you to take sides in the debates of some of the most important contributors to modern psychology.
The Scientific Method.
The four basic goals of psychology are to (1) describe, (2) explain, (3) predict, and (4) control or influence behavior and mental processes.
To achieve these goals, psychologists rely on the scientific method. The scientific method refers to a set of assumptions, attitudes, and procedures that guide researchers in creating questions to investigate, in generating evidence, and in drawing conclusions.
Like all scientists, psychologists are guided by the basic scientific assumption that events are lawful. When this scientific assumption is applied to psychology, it means that psychologists assume that behavior and mental processes follow consistent patterns.
Psychologists are also guided by the assumption that events are explainable. Thus, psychologists assume that behavior and mental processes have a cause or causes that can be understood through careful, systematic study.
In striving to discover and understand consistent patterns of behavior, psychologists are open-minded. They are willing to consider new or alternative explanations of behavior and mental processes.
However, their open-minded attitude is tempered by a healthy sense of scientific skepticism. That is, psychologists critically evaluate the evidence for new findings, especially those that seem contrary to established knowledge.
And, in promoting new ideas and findings, psychologists are cautious in the claims they make.
The Steps in the Scientific Method
Like any science, psychology is based on empirical evidence—evidence that is the result of objective observation, measurement, and experimentation. As part of the overall process of producing empirical evidence, psychologists follow the four basic steps of the scientific method. In a nutshell, these steps are:
1) Formulate a specific question that can be tested.
2) Design a study to collect relevant data.
3) Analyze the data to arrive at conclusions.
4) Report the results.
Step 1. Formulate a Hypothesis That Can Be Tested Empirically
Once a researcher has identified a question or an issue to investigate, he or she must formulate a hypothesis that can be tested empirically. Formally, a hypothesis is a tentative statement that describes the relationship between two or more variables. A hypothesis is often stated as a specific prediction that can be empirically tested, such as “psychological stress increases the likelihood of physical illness.”
The variables contained in any given hypothesis are simply the factors that can vary, or change. These changes must be capable of being observed, measured, and verified. The psychologist must provide an operational definition of each variable to be investigated. An operational definition defines the variable in terms of how it is to be measured, manipulated, or changed.
Operational definitions are important because many of the concepts that psychologists investigate—such as memory, happiness, or stress—can be measured in more than one way. In providing operational definitions of the variables in the study, the researcher spells out in very concrete and precise terms how the variables will be manipulated or measured. In this way, other researchers can understand exactly how the variables were measured or manipulated in a particular study.
Step 2. Design the Study and Collect the Data
Descriptive methods are research strategies for observing and describing behavior, including identifying the factors that seem to be associated with a particular phenomenon. Descriptive methods answer the who, what, where, and when kinds of questions about behavior. Who engages in a particular behavior? What factors or events seem to be associated with the behavior? Where does the behavior occur? When does the behavior occur? How often?
The experimental method is used to show that one variable causes change in a second variable. In an experiment, the researcher deliberately varies one factor, then measures the changes produced in a second factor. Ideally, all experimental conditions are kept as constant as possible except for the factor that the researcher systematically varies. Then, if changes occur in the second factor, those changes can be attributed to the variations in the first factor.
Step 3. Analyze the Data and Draw Conclusions
Once observations have been made and measurements have been collected, the raw data need to be summarized and analyzed.
Researchers use the methods of a branch of mathematics known as statistics to summarize, analyze, and draw conclusions about the data they have collected.
Researchers rely on statistics to determine whether their results support their hypotheses. They also use statistics to determine whether their findings are statistically significant.
If a finding is statistically significant, it means that the results are not very likely to have occurred by chance. As a rule, statistically significant results confirm the hypothesis. Appendix A provides a more detailed discussion of the use of statistics in psychology research.
Meta-analysis
A statistical technique called meta-analysis is increasingly being used in psychology to analyze the results of many research studies on a specific topic.
Basically, meta-analysis involves pooling the results of several studies into a single analysis. By creating one large pool of data to be analyzed, metaanalysis can sometimes reveal overall trends that may not be evident in individual studies.
Meta-analysis is especially useful when a particular issue has generated a large number of studies, some of which have produced weak or contradictory results.
Step 4. Report the Findings
For advances to be made in any scientific discipline, researchers must publish or share their findings with other scientists. In addition to reporting their results, psychologists provide a detailed description of the study itself, including the following:
• Who participated in the study
• How participants were selected
• How variables were operationally defined
• What procedures or methods were used
• How the data were analyzed
What the results seem to suggest
Description.
Through individual case studies, surveys among random samples of a population, and naturalistic observations, psychologists observe and describe behavior and mental processes. In generalizing from observations, remember: Representative samples are a better guide than vivid examples.
Correlation.
The strength of the relationship between one factor and another is expressed as a number in their correlation coefficient. Scatterplots and the correlations they reveal help us to see relationships that the naked eye might miss. Knowing how closely two things are positively or negatively correlated tells us how much one predicts the other. But it is crucial to remember that correlation is a measure of relationship; it does not reveal cause and effect.
Correlations also help us to discount relationships that do not exist. Illusory correlations—random events we notice and assume are related—arise from our search for patterns.
A correlational study examines how strongly two variables are related to, or associated with, each other. Correlations can be used to analyze the data gathered by any type of descriptive method.
The participants also filled out a questionnaire on past delinquent behavior and completed tests designed to measure different personality characteristics. Finally, each respondent’s cumulative grade should point average. Once the data were collected from their survey participants, psychologists used statistical procedures to calculate a figure called a correlation coefficient. A correlation coefficient is a numerical indicator of the strength of the relationship between two factors.
A positive correlation is one in which the two factors vary in the same direction. That is, the two factors increase or decrease together. For example, Anderson and Dill found that there was a positive correlation of .22 between the amount of time spent playing violent video games and aggressive personality characteristics. That is, as the amount of time spent playing violent video games increased, aggression scores on personality tests increased.
In contrast, a negative correlation is one in which the two variables move in opposite directions: As one factor decreases, the other increases. For example, Anderson and Dill found that there was a negative correlation of .20 between the amount of time spent playing video games and academic achievement, as measured by cumulative college grade-point average. As the amount of time spent playing video games increased, college grade-point average decreased.
Experimentation.
To discover cause-and-effect relationships, psychologists conduct experiments. By constructing a controlled reality, experimenters can manipulate one or more factors and discover how these independent variables affect a particular behavior, the dependent variable.
In many experiments, control is achieved by randomly assigning people either to the experimental condition, the group exposed to the treatment, or to a control condition, a group that experiences no treatment or a different version of the treatment.
Experiments examine the effects of variables on one another in order to answer questions with a level of precision that allows others to repeat the study. The aim of an experiment is to manipulate an independent variable, measure the dependent variable, and control all other variables.
The experimental method is a research method used to demonstrate a cause-end-effect relationship between changes in one variable and the effect that is produced on another variable.
Conducting an experiment involves deliberately varying one factor, which is called the independent variable. The researcher then measures the changes, if any, that are produced in a second factor, called the dependent variable. The dependent variable is so named because changes in it depend on variations in the independent variable.
To the greatest degree possible, all other conditions in the experiment are held constant. Thus, when the data are analyzed, any changes that occur in the dependent variable can be attributed to the deliberate variations of the independent variable. In this way, an experiment can demonstrate a cause-and-effect relationship between the independent and dependent variables.
The researchers used a process called random assignment to assign participants to the different experimental groups. Random assignment means that all participants in the study have an equal chance of being assigned to any of the groups in the experiment. Random assignment is an important element of good experimental design, because it helps ensure that potential differences among the participants are spread out across all experimental conditions. And, because the same criteria are used to assign all participants to the different groups in the experiment, random assignment helps make certain that the assignment of participants is done in an unbiased manner. In any well-designed experiment, there is at least one control group, or control condition.
Statistical Reasoning in Everyday Life.
To be an educated person today is to be able to apply simple statistical principles to everyday reasoning. One needn’t remember complicated formulas to think more clearly and critically about data.
From this section’s consideration of how we can organize, summarize, and make inferences from data—by constructing distributions and computing measures of central tendency, variation, and statistical significance—we derived five points to remember:
1. Doubt big, round, undocumented numbers.
2. When looking at statistical graphs in books and magazines and on television ads and news broadcasts, think critically: Always read the scale labels and note their range.
3. Always note which measure of central tendency is reported. Then, if it is a mean, consider whether a few atypical scores could be distorting it.
4. Don’t be overly impressed by a few anecdotes. Generalizations based on only a few cases are unreliable.
5. Statistical significance indicates the likelihood that a result will occur by chance. It does not indicate the importance of the result.
Describing Data.
Integrating the Findings
As research findings accumulate from individual studies, eventually theories develop. A theory, or model, is a tentative explanation that tries to account for diverse findings on the same topic. Note that theories are not the same as hypotheses. A hypothesis is a specific question or prediction to be tested. In contrast, a theory integrates and summarizes a large number of findings and observations. Along with explaining existing results, a good theory often generates predictions and new hypotheses that can be tested by further research.
As you encounter different theories, try to remember that theories are tools for explaining behavior and mental processes, not statements of absolute fact. Like any tool, the value of a theory is determined by its usefulness. A useful theory is one that furthers the understanding of behavior, allows testable predictions to be made, and stimulates new research. Often, more than one theory proves to be useful in explaining a particular area of behavior or mental processes, such as the development of personality or the experience of emotion.
It’s also important to remember that theories often reflect the self-correcting nature of the scientific enterprise. In other words, when new research findings challenge established ways of thinking about a phenomenon, theories are expanded, modified, and even replaced. Thus, as the knowledge base of psychology evolves and changes, theories evolve and change to produce more accurate and useful explanations of behavior and mental processes.
Descriptive research methods are strategies for observing and describing behavior. Using descriptive methods, researchers can answer important questions, such as when certain behaviors take place, how often they occur, and whether they are related to other factors, such as a person’s age, ethnic group, or educational level. As you’ll see in this section, descriptive methods can provide a wealth of information about behavior, especially behaviors that would be difficult or impossible to study experimentally.
Describing the precise details of the study makes it possible for other investigators to replicate, or repeat, the study. Replication is an important part of the scientific process. When a study is replicated and the same basic results are obtained again, scientific confidence that the results are accurate is increased. Conversely, if the replication of a study fails to produce the same basic findings, confidence in the original findings is reduced.
Naturalistic Observation
When psychologists systematically observe and record behaviors as they occur in their natural settings, they are using the descriptive method called naturalistic observation.
Usually, researchers engaged in naturalistic observation try to avoid being detected by their subjects, whether people or nonhuman animals.
The basic goal of naturalistic observation is to detect the behavior patterns that exist naturally—patterns that might not be apparent in a laboratory or if the subjects knew they were being watched.
Making Inferences.
The Science of People- and Animal-Watching
When psychologists systematically observe and record behaviors as they occur in their natural settings, they are using the descriptive method called naturalistic observation. Usually, researchers engaged in naturalistic observation try to avoid being detected by their subjects, whether people or nonhuman animals. The basic goal of naturalistic observation is to detect the behavior patterns that exist naturally—patterns that might not be apparent in a laboratory or if the subjects knew they were being watched.
As you might expect, psychologists very carefully define the behaviors that they will observe and measure before they begin their research. For example, social psychologist Robert Levine set out to compare the “pace of life” in 31 different countries. How could you operationally define the “pace of life”? One measure that Levine adopted was “the amount of time it took a pedestrian to walk a distance of 60 feet on a downtown city street.” To collect the data, observers unobtrusively timed at least 35 male and 35 female pedestrians in each country (Levine & Norenzayan, 1999). The results? The fastest walkers were clocked in Ireland, and the slowest in Brazil. When the 31 countries were ranked from fastest to slowest, the United States came in 6th and Canada ranked 11th. Often, to increase the accuracy of the observations, two or more observers are used. In some studies, observations are videotaped or audiotaped so that the researchers can carefully analyze the details of the behaviors being studied.
One advantage of naturalistic observation is that it allows researchers to study human behaviors that cannot ethically be manipulated in an experiment. For example, suppose that a psychologist wants to study bullying behavior in children. It would not be ethical to deliberately create a situation in which one child is aggressively bullied by another child. However, it would be ethical to study bullying by observing aggressive behavior in children on a crowded school playground. As a research tool, naturalistic observation can be used wherever patterns of behavior can be openly observed—from the rain forests of the Amazon to fastfood restaurants, shopping malls, and singles’ bars. Because the observations occur in the natural setting, the results of naturalistic observation studies can often be generalized more confidently to real-life situations than can the results of studies using artificially manipulated or staged situations.
A Case Study
A case study is an intensive, in-depth investigation of an individual or a small group of individuals. Case studies involve compiling a great deal of information, often from a variety of different sources, to construct a detailed picture of the person.
The subject may be intensively interviewed, and his or her friends, family, and co-workers may be interviewed as well. Psychological records, medical records, and even school records may be examined. Other sources of information can include extensive psychological testing and observations of the person’s behavior.
Clinical psychologists and other mental health specialists routinely use case studies to develop a complete profile of a psychotherapy client. Case studies are also used to investigate rare, unusual, or extreme conditions.
Psychological Assessments
There are several clinical psychological assessment tools and procedures. These may include clinical interviewing techniques, tests of intelligence, tests of personality and neuropsychological test batteries. In addition, there are standardized tests of achievements and aptitudes.
In the process of diagnoses and management of diverse psychological disorders, the clinical psychologists may use different types of Psychological tests. These are more structured test than the clinical interview.
However, there are some technical and psychometric requirements that should be met in a given psychological test in order to be accepted and used. These requirements include standardization and, basically, validity and reliability.
Validity deals with the question of whether the test actually measures what it is supposed to measure.
Reliability refers to the degree to which the result of a given test is repeatable. It is a measure of consistency across different time and different circumstances.
In addition, to be accepted as a clinical or diagnostic test, the test must be standardized, that is, should be accompanied with the standard procedure of administration, scoring, and interpretation of the results, as well as the norms.
Surveys
A direct way to find out about the behavior, attitudes, and opinions of people is simply to ask them. In a survey, people respond to a structured set of questions about their experiences, beliefs, behaviors, or attitudes.
One key advantage offered by survey research is that information can be gathered from a much larger group of people than is possible with other research methods.
Typically, surveys involve a carefully designed questionnaire in a paper-and-pencil format that is mailed to a select group of people. Computer-based or Internet-based surveys have become increasingly more common. And, surveys are still often conducted over the telephone or in person, with the interviewer recording the person’s responses.
As with paper-and-pencil surveys, the interviewer usually asks a structured set of questions in a predetermined order. Surveys are seldom administered to everyone within the particular group or population under investigation.
Instead, researchers usually select a sample—a segment of the larger group or population. Selecting a sample that is representative of the larger group is the key to getting accurate survey results. A representative sample very closely parallels, or matches, the larger group on relevant characteristics, such as age, sex, race, marital status, and educational level.
One potential problem with surveys and questionnaires is that people do not always answer honestly. Participants may misrepresent their personal characteristics or lie in their responses. These problems can be addressed in a well-designed survey. One strategy is to rephrase and ask the same basic question at different points in the survey or during the interview. The researchers can then compare the responses to make sure that the participant is responding honestly and consistently.
Major Intelligence Tests
Intelligence is an individual’s ability to reason, manage abstract concepts, assimilate facts, recall what has been learned, analyze and organize information, and manage the special requirements of a new situation, i.e. to cope effectively with his/her changing environment.
• The Stanford-Binet
• Wechsler intelligence tests:
• WAIS-R
• Raven Progressive Matrices
• IQ and Classification of Intelligence
Personality Tests
Personality test can basically be classified into either objective or projective tests.
An objective test based on questions that can be easily scored and statistically analyzed. All objective tests are based on the traits theory of personality.
A projective test requires the subject to interpret the questions. In this type of test, the subject’s responses are assumed to be based on motivational state and defense mechanisms. In other words, projective tests are mainly based on the Freudian psychodynamic theory of personality.Limitations of Experiments
The strength of a well-designed experiment is that it can provide convincing evidence of a cause-and-effect relationship between the independent and dependent variables.
Experiments do have limitations, however. Because experiments are often conducted in highly controlled laboratory situations, they are frequently criticized for having little to do with actual behavior. That is, the artificial conditions of some experiments may produce results that do not generalize well, meaning that the results cannot be applied to real situations or to a more general population beyond the participants in the study.
In order to make experimental conditions less artificial, experiments are sometimes conducted in a natural setting rather than in a laboratory. Another limitation of the experimental method is that even when it is possible to create the conditions that the researchers want to study, it may be unethical to do so.
Importance of Experimental Method
One major part of the work of professional psychology is to collect information about what the person does and says (Behavior, Emotion, and Cognition), and analyze these components to make sense of them. This process is called psychological assessment and it includes the collection, organization, and interpretations of information about the person and his/her situation.
This procedure varies from one application to another, depending on the purpose of assessment, i.e., whether for clinical, educational, or vocational purposes. It always involves labeling and descriptions of a person (e.g. labeling or diagnosing) as well as the classification and the prediction as in clinical screening.
THE BIOLOGY OF MIND.
CONSCIOUSNESS AND THE TWO-TRACK MIND
The Biology of Mind
Neural Communication.
The body’s circuitry, the nervous system, consists of billions of individual cells called neurons. A neuron receives signals from other neurons through its branching dendrites and cell body, combines these signals in the cell body, and transmits an electrical impulse (the action potential) down its axon. When these signals reach the end of the axon, they stimulate the release of chemical messengers called neurotransmitters.
Neurons.
The cell body contains the nucleus, which provides energy for the neuron to carry out its functions. The cell body also contains genetic material and other structures that are found in virtually all the cells in the body.
Extending out from the cell body are many short, branching fibers, called dendrites. Dendrites receive messages from other neurons or specialized cells.
The axon is a single, elongated tube that extends from the cell body in most, though not all, neurons. Axons carry information from the neuron to other cells in the body, including other neurons, glands, and muscles.
The axons of many, though not all, neurons are surrounded by the myelin sheath. The myelin sheath is a white, fatty covering anufactured by special glial cells.
The importance of myelin becomes readily apparent when it is damaged. For example, multiple sclerosis is a disease that involves the degeneration of patches of the myelin sheath. This degeneration causes the transmission of neural messages to be slowed or interrupted, resulting in disturbances in sensation and movement. Muscular weakness, loss of coordination, and speech and visual disturbances are some of the symptoms that characterize multiple sclerosis.
Neurons Communication.
Communication throughout the nervous system takes place via neurons—cells that are highly specialized to receive and transmit information from one part of the body to another. Most neurons, especially those in your brain, are extremely small. A bit of brain tissue no larger than a grain of rice contains about 10,000 neurons! Your entire brain contains an estimated 100 billion neurons. Special magnifying equipment, such as an electron microscope, is usually used to study neurons. Fortunately for neuroscientists, there are often striking similarities between the workings of the human nervous system and those of the nervous systems of many other creatures in the animal kingdom. Very simple creatures, such as sea snails and squid, tend to have larger neurons and simpler nervous systems than do humans. Neuroscientists have been able to closely observe the actions and reactions of a single neuron by studying the nervous systems of such simple animals.
There are three basic types of neurons, each communicating different kinds of information:
· Sensory neurons convey information about the environment, such as light or sound, from specialized receptor cells in the sense organs to the brain. Sensory neurons also carry information from the skin and internal organs to the brain.
· Motor neurons communicate information to the muscles and glands of the body. blinking your eyes activates thousands of motor neurons.
· Interneurons communicate information between neurons. By far, most of the neurons in the human nervous system are interneurons, and many interneurons connect to other interneurons.
Along with neurons, the human nervous system is made up of other types of specialized cells, called glial cells. Glial cells outnumber neurons by about 10 to 1, but are much smaller. Unlike neurons, glial cells do not send or receive information. Rather, they are cast in supporting roles to the major player, the neuron. Glia is Greek for “glue,” and at one time it was believed that glial cells were the glue that held the neurons of the brain together. Although they don’t actually glue neurons together, glial cells do provide structural support for neurons. Glial cells also provide nutrition, enhance the speed of communication between neurons, and remove waste products, including dead or damaged neurons. Neurons vary greatly in size and shape, reflecting their specialized functions. There are three basic types of neurons, each communicating different kinds of information.
In general, messages are gathered by the dendrites and cell body and then transmitted along the axon in the form of a brief electrical impulse called an action potential. The action potential is produced by the movement of electrically charged particles, called ions, across the membrane of the axon. Some ions are negatively charged, others positively charged. Think of the axon membrane as a gatekeeper that carefully controls the balance of positive and negative ions on the interior and exterior of the axon. As the gatekeeper, the axon membrane opens and closes ion channels that allow ions to flow into and out of the axon.
Each neuron requires a minimum level of stimulation from other neurons or sensory receptors to activate it. This minimum level of stimulation is called the neuron’s stimulus threshold. While waiting for sufficient stimulation to activate it, the neuron is said to be polarized. In this state the axon’s interior is more negatively charged than is the exterior fluid surrounding the axon. Just in case you’re wondering, scientists have measured the negative electrical charge of the neuron’s interior, using giant squid neurons to do so. And how much electricity are we discussing? About -70 millivolts (thousandths of a volt). The -70 millivolts is referred to as the neuron’s resting potential.
This polarized, negative-inside/positive-outside condition is primarily due to the different concentrations of two particular ions: sodium and potassium. While the neuron is in resting potential, the fluid surrounding the axon contains a larger concentration of sodium ions than does the fluid within the axon. The fluid within the axon contains a larger concentration of potassium ions than is found in the fluid outside the axon. When sufficiently stimulated by other neurons or sensory receptors, the neuron depolarizes, beginning the action potential. At each successive axon segment, sodium ion channels open for a mere thousandth of a second. The sodium ions rush to the axon interior from the surrounding fluid, and then the sodium ion channels close. Less than a thousandth of a second later, the potassium ion channels open, allowing potassium to rush out of the axon and into the fluid surrounding it. Then the potassium ion channels close. This sequence of depolarization and ion movement continues in a self-sustaining fashion down the entire length of the axon.
As sodium ions penetrate the axon membrane and potassium ions exit, the electrical charge on the inside of the axon momentarily changes to a positive electrical charge of about +30 millivolts. The result is a brief positive electrical impulse that progressively occurs at each segment down the axon—the action potential. Although it’s tempting to think of the action potential as being conducted much as electricity is conducted through a wire, that’s not what takes place in the neuron. The axon is actually a poor conductor of electricity. At each successive segment of the axon, the action potential is regenerated in the same way in which it was generated in the previous segment—by depolarization and the movement of ions.
Once the action potential is started, it is self-sustaining and continues to the end of the axon. In other words, there is no such thing as a partial action potential. Either the neuron is sufficiently stimulated and an action potential occurs, or the neuron is not sufficiently stimulated and an action potential does not occur. This principle is referred to as the all-or-none law. Following the action potential, a refractory period occurs during which the neuron is unable to fire. This period lasts for a mere thousandth of a second or less. During the refractory period, the neuron repolarizes and reestablishes the negative-inside/positive-outside condition. Like depolarization, repolarization occurs progressively at each segment down the axon. This process of pumping sodium ions out and drawing potassium ions back in reestablishes the resting potential conditions so that the neuron is capable of firing again.
Remember, action potentials are generated in mere thousandths of a second. Thus, a single neuron can potentially generate hundreds of neural impulses per second. Given these minute increments of time, just how fast do neural impulses zip around the body? The fastest neurons in your body communicate at speeds of up to 270 miles per hour. In the slowest neurons, messages creep along at about 2 miles per hour. This variation in communication speed is due to two factors: the axon diameter and the myelin sheath. The greater the axon’s diameter, the faster the axon conducts action potentials. And, as we said earlier, myelinated neurons communicate faster than unmyelinated neurons. In myelinated neurons, the sodium ion channels are concentrated at each of the nodes of Ranvier where the myelin is missing. So, in myelinated neurons the action potential jumps from node to node rather than progressing down the entire length of the axon.
The primary function of a neuron is to communicate information to other cells, most notably other neurons. The point of communication between two neurons is called the synapse. At this communication junction, the message-sending neuron is referred to as the presynaptic neuron. The message-receiving neuron is called the postsynaptic neuron. For cells that are specialized to communicate information, neurons have a surprising characteristic: They don’t touch each other. The presynaptic and postsynaptic neurons are separated by a tiny, fluidfilled space, called the synaptic gap, which is only about five-millionths of an inch wide.
Neurotransmitters Influence.
The transmission of information between two neurons occurs in one of two ways: electrically or chemically. When communication is electrical, the synaptic gap is extremely narrow, and special ion channels serve as a bridge between the neurons. Electrical communication between the two neurons is virtually instantaneous.
Although some neurons in the human nervous system communicate electrically, over 99 percent of the synapses in the brain use chemical transmission. In general terms, chemical communication occurs when the presynaptic neuron creates a chemical substance that diffuses across the synaptic gap and is detected by the postsynaptic neuron. This one-way communication process between one neuron and another has many important implications for human behavior.
Along with neurons, the human nervous system is made up of other types of specialized cells, called glial cells between neurons and blood vessels in the brain.
There are three basic types of neurons, each communicating different kinds of information:
1. Sensory neurons convey information about the environment, such as light or sound, from specialized receptor cells in the sense organs to the brain. Sensory neurons also carry information from the skin and internal organs to the brain.
2. Motor neurons communicate information to the muscles and glands of the body. blinking your eyes activates thousands of motor neurons.
3. Interneurons communicate information between neurons. By far, most of the neurons in the human nervous system are interneurons, and many interneurons connect to other interneurons.
The cell body contains the nucleus, which provides energy for the neuron to carry out its functions. The cell body also contains genetic material and other structures that are found in virtually all the cells in the body.
Extending out from the cell body are many short, branching fibers, called dendrites. Dendrites receive messages from other neurons or specialized cells.
The axon is a single, elongated tube that extends from the cell body in most, though not all, neurons. Axons carry information from the neuron to other cells in the body, including other neurons, glands, and muscles.
The axons of many, though not all, neurons are surrounded by the myelin sheath. The myelin sheath is a white, fatty covering anufactured by special glial cells.
In the brain, as in the rest of the nervous system, information is transmitted by electrical impulses that speed from one neuron to the next. The point of communication between two neurons is called the synapse. The transmission of information between two neurons occurs in one of two ways: electrically or chemically. One neuron will transmit info to another neuron or to a muscle or gland cell by releasing chemicals called neurotransmitters.
The site of this chemical interplay is known as the synapse.
An axon terminal (synaptic knob) will abut another cell, a neuron, muscle fiber, or gland cell. This is the site of transduction – the conversion of an electrical signal into a chemical signal. The molecules pass on their excitatory or inhibitory messages as they traverse the synaptic gap between neurons and combine with receptor sites on neighboring neurons. Researchers are studying neurotransmitters to discern their role in behavior and emotion. Some drugs (agonists) excite by mimicking particular neurotransmitters or blocking their reuptake; others (antagonists) inhibit by blocking neurotransmitters.
More specifically, here’s how chemical communication takes place between neurons. As we’ve seen, when the presynaptic neuron is activated, it generates an action potential that travels to the end of the axon. At the end of the axon are several small branches called axon terminals. Floating in the interior fluid of the axon terminals are tiny sacs called synaptic vesicles. The synaptic vesicles hold special chemical messengers manufactured by the neuron, called neurotransmitters.
When the action potential reaches the axon terminals, some of the synaptic vesicles “dock” on the axon terminal membrane, then release their neurotransmitters into the synaptic gap. These chemical messengers cross the synaptic gap and attach to receptor sites on the dendrites of the surrounding neurons. This journey across the synaptic gap is slower than electrical transmission, but is still extremely rapid; it takes less than ten-millionths of a second. The entire process of transmitting information at the synapse is called synaptic transmission. What happens to the neurotransmitter molecules after they’ve attached to the receptor sites of the postsynaptic neuron? Most often, they detach from the receptor and are reabsorbed by the presynaptic neuron so they can be recycled and used again. This process is called reuptake. Reuptake also occurs with many of the neurotransmitters that failed to attach to a receptor and are left floating in the synaptic gap. Neurotransmitter molecules that are not reabsorbed or that remain attached to the receptor site are broken down or destroyed by enzymes. As you’ll see in the next section, certain drugs can interfere with both of these processes, prolonging the presence of the neurotransmitter in the synaptic gap.
The number of neurotransmitters that a neuron can manufacture varies. Some neurons produce only one type of neurotransmitter, whereas others manufacture three or more. Although estimates vary, scientists have thus far identified more than 100 different compounds that function as neurotransmitters in the brain.
Each type of neurotransmitter has a chemically distinct, different shape. When released by the presynaptic neuron, neurotransmitters search for the correctly shaped receptor sites on the dendrites of the postsynaptic neurons. Like a key in a lock, a neurotransmitter’s shape must precisely match that of a receptor site on the postsynaptic neuron’s dendrites for the neurotransmitter to affect that neuron. Keep in mind that the postsynaptic neuron can have many differently shaped receptor sites on its dendrites and thus may accommodate several different neurotransmitters.
Excitatory and Inhibitory Messages
A neurotransmitter communicates either an excitatory or an inhibitory message to a postsynaptic neuron. An excitatory message increases the likelihood that the postsynaptic neuron will activate and generate an action potential. Conversely, an inhibitory message decreases the likelihood that the postsynaptic neuron will activate. If a postsynaptic neuron receives an excitatory and an inhibitory message simultaneously, the two messages cancel each other out.
It’s important to note that the effect of any particular neurotransmitter depends on the particular receptor to which it binds. So, the same neurotransmitter can have an inhibitory effect on one neuron and an excitatory effect on another. Depending on the number and kind of neurotransmitter chemicals that are taken up by the dendrites of the adjoining neurons, the postsynaptic neurons are more or less likely to activate. If the net result is a sufficient number of excitatory messages, the postsynaptic neuron depolarizes, generates an action potential, and releases its own neurotransmitters. When released by a presynaptic neuron, neurotransmitter chemicals cross hundreds, even thousands, of synaptic gaps and affect the intertwined dendrites of adjacent neurons. Because the receiving neuron can have thousands of dendrites that intertwine with the axon terminals of many presynaptic neurons, the number of potential synaptic interconnections between neurons is mind-boggling. On the average, each neuron in the brain communicates directly with 1,000 other neurons. Thus, in your brain alone, there are up to 100 trillion synaptic interconnections.
Neurotransmitters and Their Effects
Your ability to perceive, feel, think, move, act, and react depends on the delicate balance of neurotransmitters in your nervous system. Too much or too little of a given neurotransmitter can have devastating effects. Yet neurotransmitters are present in only minuscule amounts in the human body. If you imagine trying to detect a pinch of salt dissolved in an Olympic-sized swimming pool, you will have some idea of the infinitesimal amounts of neurotransmitters present in brain tissue. In this section, you’ll see that researchers have linked abnormal levels of specific neurotransmitters to various physical and behavioral problems. Nevertheless, it’s important to remember that any connection between a particular neurotransmitter and a particular effect is not a simple one-to-one relationship. Many behaviors are the result of the complex interaction of different neurotransmitters. Further, neurotransmitters sometimes have different effects in different areas of the brain.
Important Neurotransmitters
· Acetylcholine -learning, memory, muscle contractions
· Dopamine – movement, thought processes, rewarding sensations
· Serotonin - emotional states, sleep
· Norepinephrine - physical arousal, learning, memory
· GABA - Inhibition of brain activity
· Endorphins Pain perception Positive emotions
The Nervous System.
The central nervous system’s neurons in the brain and spinal cord communicate with the peripheral nervous system’s sensory and motor neurons. The peripheral nervous system has two main divisions. The somatic nervous system directs voluntary movements and reflexes. The autonomic nervous system, through its sympathetic and parasympathetic divisions, controls our involuntary muscles and glands. Like people clustering into neighborhoods, neurons cluster into working networks.
The Peripheral Nervous System.
The peripheral nervous system is the other major division of your nervous system. The word peripheral means “lying at the outer edges.” Thus, the peripheral nervous system comprises all the nerves outside the central nervous system that extend to the outermost borders of your body, including your skin. The communication functions of the peripheral nervous system are handled by its two subdivisions: the somatic nervous system and the autonomic nervous system. The somatic nervous system takes its name from the Greek word soma, which means “body.” It plays a key role in communication throughout the entire body. First, the somatic nervous system communicates sensory information received by sensory receptors along sensory nerves to the central nervous system. Second, it carries messages from the central nervous system along motor nerves to perform voluntary muscle movements. All the different sensations that you’re experiencing right now are being communicated by your somatic nervous system to your spinal cord and on to your brain. When you perform a voluntary action,such as turning a page of this book, messages from the brain are communicated down the spinal cord, then out to the muscles via the somatic nervous system. The other subdivision of the peripheral nervous system is the autonomic nervous system. The word autonomic means “self-governing.” Thus, the autonomic nervous system regulates involuntary functions, such as heartbeat, blood pressure, breathing, and digestion. These processes occur with little or no conscious involvement. This is fortunate, because if you had to mentally command your heart to beat or your stomach to digest the pizza you had for lunch, it would be difficult to focus your attention on anything else.
However, the autonomic nervous system is not completely self-regulating. By engaging in physical activity or purposely tensing or relaxing your muscles, you can increase or decrease autonomic activity. Emotions and mental imagery also influence your autonomic nervous system. Vividly imagining a situation that makes you feel angry, frightened, or even sexually aroused can dramatically increase your heart rate and blood pressure. A peaceful mental image can lower many autonomic functions. The involuntary functions regulated by the autonomic nervous system are controlled by two different branches: the sympathetic and parasympathetic nervous systems. These two systems control many of the same organs in your body but cause them to respond in opposite ways. In general, the sympathetic nervous system arouses the body to expend energy, and the parasympathetic nervous system helps the body conserve energy.
The sympathetic nervous system is the body’s emergency system, rapidly activating bodily systems to meet threats or emergencies. When you are frightened, your breathing accelerates, your heart beats faster, digestion stops, and the bronchial tubes in your lungs expand. All these physiological responses increase the amount of oxygen available to your brain and muscles. Your pupils dilate to increase your field of vision, and your mouth becomes dry, because salivation stops. You begin to sweat in response to your body’s expenditure of greater energy and heat. These bodily changes collectively represent the fight-or-flight response—they physically prepare you to fight or flee from a perceived danger. Whereas the sympathetic nervous system mobilizes your body’s physical resources, the parasympathetic nervous system conserves and maintains your physical resources. It calms you down after an emergency. Acting much more slowly than the sympathetic nervous system, the parasympathetic nervous system gradually returns your body’s systems to normal. Heart rate, breathing, and blood pressure level out. Pupils constrict back to their normal size. Saliva returns, and the digestive system begins operating again. Although the sympathetic and parasympathetic nervous systems produce opposite effects, they act together, keeping the nervous system in balance. Each division handles different functions, yet the whole nervous system works in unison so that both automatic and voluntary behaviors are carried out smoothly.
Sympathetic nervous system - branch of the autonomic nervous system that produces rapid physical arousal in response to perceived emergencies or threats.
Parasympathetic nervous system - branch of the autonomic nervous system that maintains normal bodily functions and conserves the body’s physical
Sympathetic - “Fight or flight”. “E” division - Exercise, excitement, emergency, and embarrassment
Parasympathetic - “Rest and digest”. “D” division - Digestion, defecation, and diuresis.
The Central Nervous System.
The central nervous system includes the brain and the spinal cord. The central nervous system is so critical to your ability to function that it is entirely protected by bone—the brain by your skull and the spinal cord by your spinal column. As an added measure of protection, the brain and spinal cord are suspended in cerebrospinal fluid to protect them from being jarred. The central nervous system is aptly named. It is central to all your behaviors and mental processes. And it is the central processing center—every action, thought, feeling, and sensation you experience is processed through the central nervous system. The most important element of the central nervous system is, of course, the brain, which acts as the command center. We’ll take a tour of the human brain in a later section. Think of the spinal cord as an old-fashioned but very busy telephone switchboard, handling both incoming and outgoing messages. Sensory receptors send messages along sensory nerves to the spinal cord, then up to the brain. To activate muscles, the brain sends signals down the spinal cord, which are relayed out along motor nerves to the muscles.
Most behaviors are controlled by your brain. However, the spinal cord can produce spinal reflexes—simple, automatic behaviors that occur without any brain involvement. One of the simplest spinal reflexes involves a three-neuron loop of rapid communication—a sensory neuron that communicates sensation to the spinal cord, an interneuron that relays information within the spinal cord, and a motor neuron leading from the spinal cord that signals muscles to react.
Spinal reflexes are crucial to your survival. The additional few seconds that it would take you to consciously process sensations and decide how to react could result in serious injury. Spinal reflexes are also important as indicators that the neural pathways in your spinal cord are working correctly. That’s why physicians test spinal reflexes during neurological examinations by tapping just below your kneecap for the knee-jerk spinal reflex or scratching the sole of your foot for the toe-curl spinal reflex.
Reflex - a simple, automatic, inborn response to a sensory stimulus.
The Endocrine System.
Endocrine glands communicate information from one part of the body to another by secreting messenger chemicals called hormones into the bloodstream. The endocrine system, one of the body’s communication systems, is a kindred system to the nervous system. Its glands release hormones at a slower rate than neurotransmitters, resulting in a longer lasting effect. The feeling outlasts the thought.
The hormones circulate throughout the bloodstream until they reach specific hormone receptors on target organs or tissue. By interacting with the nervous system and affecting internal organs and body tissues, hormones regulate physical processes and influence behavior in a variety of ways.
Metabolism, growth rate, digestion, blood pressure, and sexual development and reproduction are just some of the processes that are regulated by the endocrine hormones. Hormones are also involved in emotional response and your response to stress. Endocrine hormones are closely linked to the workings of the nervous system. For example, the release of hormones may be stimulated or inhibited by certain parts of the nervous system. In turn, hormones can promote or inhibit the generation of nerve impulses. Finally, some hormones and neurotransmitters are chemically identical. The same molecule can act as a hormone in the endocrine system and as a neurotransmitter in the nervous system. In contrast to the rapid speed of information transmission in the nervous system, communication in the endocrine system takes place much more slowly. Hor mones rely on the circulation of the blood to deliver their chemical messages to target organs, so it may take a few seconds or longer for the hormone to reach its target organ after it has been secreted by the originating gland. The signals that trigger the secretion of hormones are regulated by the brain, primarily by a brain structure called the hypothalamus. The hypothalamus serves as the main link between the endocrine system and the nervous system. The hypothalamus directly regulates the release of hormones by the pituitary gland, a pea-sized gland just under the brain. The pituitary’s hormones, in turn, regulate the production of other hormones by many of the glands in the endocrine system. This is why the pituitary gland is often referred to as the body’s master gland. Under the direction of the hypothalamus, the pituitary gland controls hormone production in other endocrine glands.
Nervous & Endocrine System
Similarities:
They both monitor stimuli and react so as to maintain homeostasis.
Differences:
The NS is a rapid, fast-acting system whose effects do not always persevere.
The ES acts slower and its actions are usually much longer lasting.
The central nervous system includes the brain and the spinal cord.
This is the primary internal communication network of the body; divided into the central nervous system and the peripheral nervous system.
The Brain.
Clinical observations have long revealed the general effects of damage to various areas of the brain. But CT and MRI scans now reveal brain structures, and EEG, PET, and functional MRI recordings reveal brain activity. By surgically lesioning or electrically stimulating specific brain areas, by recording the brain’s surface electrical activity, and by displaying neural activity with computer-aided brain scans, neuroscientists explore the connections among brain, mind, and behavior.
Older Brain Structures.
The brainstem begins where the spinal cord swells to form the medulla, which controls heartbeat and breathing. Within the brainstem, the reticular formation controls arousal. Atop the brainstem is the thalamus, the brain’s sensory switchboard. The cerebellum, attached to the rear of the brainstem, coordinates muscle movement.
Between the brainstem and cerebral cortex is the limbic system, which is linked to memory, emotions, and drives. One of its neural centers, the amygdala, is involved in responses of aggression and fear. Another, the hypothalamus, is involved in various bodily maintenance functions, pleasurable rewards, and the control of the hormonal system.
The Cerebral Cortex.
The outer portion of the forebrain, the cerebral cortex, is divided into two cerebral hemispheres. The word cortex means “bark,” and much like the bark of a tree, the cerebral cortex is the outer covering of the forebrain. A thick bundle of axons, called the corpus callosum, connects the two cerebral hemispheres. The corpus callosum serves as the primary communication link between the left and right cerebral hemispheres. The cerebral cortex is only about a quarter of an inch thick. It is mainly composed of glial cells and neuron cell bodies and axons, giving it a grayish appearance—which is why the cerebral cortex is sometimes described as being composed of gray matter. Extending inward from the cerebral cortex are white myelinated axons that are sometimes referred to as white matter. These myelinated axons connect the cerebral cortex to other brain regions. Numerous folds, grooves, and bulges characterize the human cerebral cortex. The purpose of these ridges and valleys is easy to illustrate. Imagine a flat, three-foot by threefoot piece of paper. You can compact the surface area of this piece of paper by scrunching it up into a wad. In much the same way, the grooves and bulges of the cerebral cortex allow about three square feet of surface area to be packed into the small space of the human skull.
Each hemisphere of the cerebral cortex—the neural fabric that covers the hemispheres—has four geographic areas: the frontal, parietal, occipital, and temporal lobes. Small, well-defined regions within these lobes control muscle movement and receive information from the body senses. However, most of the cortex—its association areas—is uncommitted to such functions and is therefore free to process other information.
Some brain regions serve specific functions. The brain divides its labor into specialized subtasks and then integrates the various outputs from its neural networks. Thus, our emotions, thoughts, and behaviors result from the intricate coordination of many brain areas. Language, for example, depends on a chain of events in several brain regions. If one hemisphere is damaged early in life, the other will pick up many of its functions, thus demonstrating the brain’s plasticity. The brain becomes less plastic later in life. Frequently, however, nearby neurons can partially compensate for damaged ones, as when a person recovers from a stroke or brain injury.
Many psychological processes, particularly complex ones, involve multiple brain structures and regions. Even seemingly simple tasks—such as carrying on a conversation or catching a ball—involve the smoothly coordinated synthesis of information among many different areas of your brain.
Right-Left Differences in the Intact Brain.
Clinical observations long ago revealed that the left cerebral hemisphere is crucial for language. Experiments on people with a severed corpus callosum have refined our knowledge of each hemisphere’s special functions. Separately testing the two hemispheres, researchers have confirmed that in most people the left hemisphere is the more verbal, and that the right hemisphere excels in visual perception and the recognition of emotion. Studies of healthy people with intact brains confirm that each hemisphere makes unique contributions to the integrated functioning of the brain.
Biological psychology is the scientific study of the biological bases of behavior and mental processes. This area of research is also called biopsychology. Both terms emphasize the idea of a biological approach to the study of psychological processes.
Biological psychology is one of the scientific disciplines that makes important contributions to neuroscience—the scientific study of the nervous system. As neuroscientists, biopsychologists bring their expertise in behavior and behavioral research to this scientific endeavor.
Some of the other scientific disciplines that contribute to neuroscience include physiology, pharmacology, biology, and neurology.
Communication throughout the nervous system takes place via neurons—cells that are highly specialized to receive and transmit information from one part of the body to another.
Drugs and Consciousness
Psychoactive Drugs.
Much of what is known about different neurotransmitters has been learned from observing the effects of drugs and other substances. Many drugs, especially those that affect moods or behavior, work by interfering with the normal functioning of neurotransmitters in the synapse. Some drugs increase or decrease the amount of neurotransmitter released by neurons. For example, the venom of a black widow spider bite causes acetylcholine to be released continuously by motor neurons, causing severe muscle spasms. Drugs may also affect the length of time the neurotransmitter remains in the synaptic gap, either increasing or decreasing the amount available to the postsynaptic receptor. One way in which drugs can prolong the effects of the neurotransmitter is by blocking the reuptake of the neurotransmitter by the sending neuron. For example, Prozac inhibits the reuptake of serotonin, increasing the availability of serotonin in the brain. The illegal drug cocaine produces its exhilarating rush by interfering with the reuptake of dopamine. Drugs can also mimic specific neurotransmitters. When a drug is chemically similar to a specific neurotransmitter, it may produce the same effect as that neurotransmitter.
It is partly through this mechanism that nicotine works as a stimulant. Nicotine is chemically similar to acetylcholine and can occupy acetylcholine receptor sites, stimulating skeletal muscles and causing the heart to beat more rapidly. Alternatively, a drug can mimic and block the effect of a neurotransmitter by fitting into receptor sites and preventing the neurotransmitter from acting. For example, the drug curare mimics acetylcholine and blocks acetylcholine receptor sites, causing almost instantaneous paralysis. The brain sends signals to the motor neurons, but the muscles can’t respond because the motor neuron receptor sites are blocked by the curare. Similarly, a drug called naloxone eliminates the effects of both endorphins and opiates by blocking opiate receptor sites.
With the discovery of the electrophysiological bases of behavior, investigators jumped to the conclusion that the impulse jumped across the space, much like a spark traversing a close connection. But improved research methods have indicated instead that special chemical substances are involved in synaptic connections.
At the ends of all presynaptic neurons are small vesicles containing a neurotransmitter substance, a chemical that is discharged into the synaptic space and travels across it to act on the membrane of the adjacent fiber. Sometimes this chemical makes the receiving membrane become depolarized, causing a discharge in that membrane. In other instances, it makes the receiving membrane more polarized and therefore more resistant to firing. In a broad sense, there are two kinds of junctions, excitatory synapses and inhibitory synapses, and they result in activation or inhibition, depending upon which neurotransmitter substances are involved.
In other words, there is no difference among the electrical impulses at the synapses, but there are critical differences among the neurotransmitters at work. The neurotransmitter called catecholamine, for example, appears to be involved in mood changes; a depletion of this substance induces depression and an abnormally high amount is influential in euphoria. Similarly, an abnormally high level of another neurotransmitter, dopamine, appears related to certain psychotic reactions. Altogether, modern research suggests that there are many different neurotransmitters in the various synapses, seemingly related to different behaviors and experiences.
The widespread use of certain drugs is partly understood in this context. One of the many outcomes of alcohol consumption, for example, is the blocking of certain neurotransmitters responsible for brain activity, eventually inducing sleep. But the work of other neurotransmitters apparently is disrupted in this process, and the person may awaken earlier than usual or experience disturbed sleep. A light snack before bedtime can lead to increased production of serotonin, a neurotransmitter associated with food metabolism, producing drowsiness, much to the discomfort of the after-dinner speaker. Still further, morphine and heroin have a chemical structure much like endorphin, and this neurotransmitter, produced naturally by the body, is related to the reduction of pain. Various hallucinogenic drugs appear to have their pronounced effects on consciousness because their chemical structure is similar to that of the natural neurotransmitters at work in the brain.
Dependence and Addiction.
Continued use of alcohol and other psychoactive drugs produces tolerance. As the user’s brain adapts its chemistry to offset the drug effect (a process called neuroadaptation), the user requires larger and larger doses to experience the same effect. Despite the connotations of alcohol “tolerance,” an alcoholic’s brain, heart, and liver suffer damage from the excessive alcohol being “tolerated.”
Users who stop taking psychoactive drugs may experience the undesirable side effects of withdrawal. As the body responds to the drug’s absence, the user may feel physical pain and intense cravings, indicating physical dependence. People can also develop psychological dependence, particularly for stress-relieving drugs. Such drugs, although not physically addictive, can become an important part of the user’s life, often as a way of relieving negative emotions. With either physical or psychological dependence, the user’s primary focus may be obtaining and using the drug.
Influences on Drug Use.
Biological Influences
Some people may be biologically vulnerable to particular drugs. For example, evidence accumulates that heredity influences some aspects of alcohol abuse problems, especially those appearing by early adulthood:
• Adopted individuals are more susceptible to alcohol dependence if one or both biological parents have a history of it.
• Having an identical rather than fraternal twin with alcohol dependence puts one at increased risk for alcohol problems.
• Boys who at age 6 are excitable, impulsive, and fearless (genetically influenced traits) are more likely as teens to smoke, drink, and use other drugs.
• Researchers have bred rats and mice that prefer alcoholic drinks to water. One such strain has reduced levels of the brain chemical NPY. Mice engineered to overproduce NPY are very sensitive to alcohol’s sedating effect and drink little.
• Researchers have identified genes that are more common among people and animals predisposed to alcoholism, and they are seeking genes that contribute to tobacco addiction. These culprit genes seemingly produce deficiencies in the brain’s natural dopamine reward system, which is impacted by addictive drugs. When repeated, the drugs trigger dopamine-produced pleasure but also disrupt normal dopamine balance.
Psychological and social-cultural influences also contribute to drug use. Heavy users of alcohol, marijuana, and cocaine often display other psychological influences. Many have experienced significant stress or failure and are depressed.
Consciousness.
Cognitive neuroscientists and others studying the brain mechanisms underlying consciousness and cognition have discovered a two-track human mind, each with its own neural processing. This dual processing affects our perception, memory, and attitudes at an explicit, conscious level and at an implicit, unconscious level.
We selectively attend to, and process, a very limited aspect of incoming information, blocking out most, often shifting the spotlight of our attention from one thing to another. The limits of our attention contribute to car and pedestrian accidents. We even display inattentional blindness to events and changes in our visual world.
Near-Death Experiences
In studies of those who have come close to death through cardiac arrest or other physical traumas, 12 to 40 percent recalled a near-death experience. Patients who have experienced temporal lobe seizures have reported profound mystical experiences, sometimes similar to those of near-death experiences. When researchers stimulated the crucial temporal lobe area of one such patient, she reported a sensation of “floating” near the ceiling and seeing herself, from above, lying in bed.
Oxygen deprivation can produce such hallucinations, complete with tunnel vision. As oxygen deprivation turns off the brain’s inhibitory cells, neural activity increases in the visual cortex. In the oxygen-starved brain, the result is a growing patch of light, which looks much like what you would see as you moved through a tunnel. The near-death experience is best understood as “hallucinatory activity of the brain.”
This is a composite description of a near-death experience.
“A man hears himself pronounced dead by his doctor. He begins to hear an uncomfortable noise, a loud ringing or buzzing, and at the same time feels himself moving very rapidly through a long dark tunnel. After this, he suddenly finds himself outside of his own physical body and sees his own body from a distance, as though he is a spectator. Soon other things begin to happen. Others come to meet and to help him. He glimpses the spirits of relatives and friends who have already died, and a loving, warm spirit of a kind he has never encountered before—a being of light—appears before him. He is overwhelmed by intense feelings of joy, love, and peace. Despite his attitude, though, he somehow reunites with his physical body and lives.