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Transcript
Physiological Psychology PSYC370 Thomas E. Van Cantfort, Ph.D. Introduction Roots of Physiological Psychology The nervous system, the final frontier. To boldly go where no one has gone before. ‚ The human nervous system makes possible Ú all that we can do, Ú all that we can know, Ú all that we can experience. ‚ Its complexity is immense, ‚ and the task of studying it and understanding it ‚ dwarfs all previous explorations our species has undertaken.L ‚ ‚ Introduction Introduction to Physiological Psychology Roots of Physiological Psychology Roots of Physiological Psychology Investigation of the physiology of behavior has a long history, with roots in Ú philosophy Ú biology Ú and psychology. ‚ Philosophers have asked how we perceive and understand reality Biologists have devised experimental physiology, which provides the tools we use to investigate the workings of the body. ‚ They have also developed the framework needed to integrate findings from diverse species: Ú the principle of natural selection, Ú evolution, Ú and genetics. ‚ Psychologists have devised methods of Ú behavioral observation and analysis Ú and presented many of the theoretical questions that motivated much of the research being performed today.L ‚ ‚ and have posed the mind/body question, which remains with us still. ‚ They have also devised the scientific method – a set of rules that permits us to ask questions about the natural world with some assurance that we receive reliable answers.L ‚ Philosophical Roots of Physiological Psychology ‚ ‚ Philosophy (comes from the Greek meaning loving wisdom) originally concerned itself with the basis of human knowledge and thought. Philosophers soon realized that in order to understand the basis of knowledge, they must understand the nature of reality, Ú which led them to develop natural philosophy, the predecessor to modern physical and biological science. Ú In ancient times people believed that natural phenomena were caused by animating spirits. Ú All moving objects – animals, the wind and tides, the sun, moon, and stars – were assumed to have spirits that caused them to move. < For example, stones fell when they were dropped because their animating spirits wanted to be reunited with Mother Earth.L Philosophical Roots continued As our ancestors became more sophisticated and learned more about nature, ‚ they abandoned this approach – which we call animism – in favor of physical explanations for inanimate moving objects. Ú But they still used spirits to explain human behavior. ‚ From the earliest historical times people have believed they possess souls. Ú This belief stems from our awareness of our own existence. < When we think or act, we feel as if something inside us – our mind or our soul – is thinking or deciding to act. • This method of looking inward is called introspection.L ‚ Philosophical Roots continued ‚ ‚ But what is the nature of the mind? Ú We have physical bodies, Ú equipped with muscles that move it Ú a sensory organs such as the eyes and ears Ú that perceive information about the world around us. Within our bodies the nervous system plays a central role, Ú controlling the movements of the muscles Ú and receiving information from the sensory organs. Ú But what role does the mind play? < Does it control the nervous system? < Is it a part of the nervous system? < Is it physical and tangible, like the rest of the body, < or is it a spirit that will always remain hidden? < Or is there a mind at all?L Philosophical Roots continued ‚ ‚ ‚ ‚ ‚ Dualism ‚ ‚ ‚ ‚ ‚ Early philosophers believed that reality was divided into two categories: Ú the material Ú and the spiritual. According to this belief, humans have physical bodies and nonphysical spirits, or souls. Mind and body are considered to be separate; the body is made of ordinary matter, Ú but the mind is not. Ú This belief is called dualism. Ú Those who hold this belief are known as dualist. But if the physical and spiritual aspects of our nature are independent, as this model suggests, L Dualism continued ‚ ‚ ‚ ‚ This puzzle has historically been called the mind-body question. Philosophers have been trying to answer it for many centuries, and more recently, scientists have taken up the task. Basically, people have followed two different approaches: dualism and monism. As we shall see, these two approaches reflect very different assumptions about the nature of reality.L Dualism continued then what is the purpose of having both, or in what way are they related? ‚ If the body functions independently of the soul, then what does the soul do? ‚ The concept of soul is the cornerstone of religion; philosophers were therefore unwilling to dispense with it. ‚ Instead, they suggested that the soul controls the body. ‚ Because the eyes and ears – the primary windows to the soul – are located in the head, ‚ The probable location of the soul was presumed to be the brain.L ‚ ‚ Dualism continued Moreover, damage to the head can lead to unconsciousness or paralysis, which suggested that the soul moved the body by controlling the operations of the brain. In the seventeenth century (1660) the French philosopher and mathematician René Descartes attempted to explain how the soul could control the body. His explanation is known as Cartesian Dualism.L René Descartes L Cartesian Dualistic Model Dualism continued ‚ ‚ ‚ ‚ ‚ Descartes believed that animals other than humans were machines (a mechanistic view). If we could understand how their parts were put together, we should be able to understand them completely. According the Descartes the bodies of humans were also machines and operated on exactly the same principles. However, unlike other animals, we had a God-given soul.L Descartes identified two types of behaviors, voluntary and involuntary behaviors.L ‚ Cartesian Dualistic Model continued ‚ Involuntary behavior according to Descartes were elicited by external stimuli. Ú Descartes formulated the first physiological model of behavior. Ú He based his model on the mechanism that activated the statues in the grottoes of the Royal Gardens at Versailles just west of Paris. Ú As a young man, he was fascinated by the hidden mechanisms that caused the statues to move and dance when visitors stepped on hidden plates. Ú The statues were moved by hydraulic cylinders powered by water pressure. Ú Descartes believed that the muscles of the body also worked hydraulically.L Cartesian Dualistic Model continued Ú When ‚ we exert a force with our limbs, our muscle appears to get larger. Ú Descartes concluded that this enlargement occurs because fluid, which he called animal spirits, is pumped into the muscles through the nerves. Ú When nerves are cut, liquid oozes out; hence the nerves must be hollow. What is the source of the fluid that gets pumped into the muscles? Ú According to Descartes, it was the cerebral ventricles – the hollow, fluid-filled chambers of the brain. Ú He concluded that the mechanism that directed the pressurized fluid into the appropriate nerves was the pineal gland, Ú a small organ situated on top of the brain stem.L Cartesian Dualistic Model continued Ú The ‚ ‚ pineal gland acted like a little joystick: when it was tilted slightly in various direction, Ú it opened pores that permitted fluid to enter the nerves and inflate the mucles. Ú Because animals lacked souls, Descartes believed that this model completely explained their behavior. Humans, however, possessed souls as well as bodies. Humans had voluntary behavior. That is conscious control of behavior. Ú The pineal gland, which controlled the movements of the pressurized fluids through the nerves to the muscles, Ú provided the place for the soul to interact with the body.L Cartesian Dualistic Model continued Ú The soul received information about the world through the body’s senses, Ú thought about what it perceived, Ú and made decisions about actions. Ú When it wanted to move the body, it did so by acting on the brain, Ú which, in turn, moved the muscles. Ú When the soul desired a particular action, it tilted the pineal gland appropriately, Ú and the muscles needed to carry out the action became inflated.L Cartesian Dualistic Model continued Monism ‚ ‚ Descartes’s theory contains a built-in contradiction. Ú If the soul or mind is not a part of the physical world, Ú then it cannot exert a force that moves physical objects. Ú Thus it cannot interact with matter. If the soul or mind possesses material properties that permit it to interact with the body, then it, like the body, is physical. ‚ Logically, we cannot have it both ways.L ‚ ‚ ‚ ‚ Physiological psychologists take an empirical, practical, and monistic approach to the study of human nature. ‚ Monism is the belief that reality consists of a unified whole and, thus, that the mind is a phenomenon produced by the working of the body. The monist believe that once we understand how the body works – in particular, how the nervous system works – the mind-body problem will have been solved.L ‚ Monism continued What monist call “mind” is consequence of the functioning of the body and its interaction with environment. ‚ The mind is an epiphenomenon – a by product of the brain’s activities.L ‚ Biological Roots of Physiological Psychology Not all modern philosophers are monist, and not all believe that the human mind is based on physiological functioning. ‚ Yet scientists who study the physiology of behavior trace their intellectual ancestry to the monistic, deterministic school of philosophy. ‚ This school encouraged the development of natural scientist, ‚ who first studied living organisms in the world around them ‚ and eventually applied their techniques and principles to the study of human behavior.L ‚ ‚ Biological Roots continued Biological Roots continued Although such early natural philosophers as Aristotle speculated about the causes of behavior, ‚ René Descartes’s physiological model provides a good starting place for a discussion of the biological roots of physiological psychology. ‚ His model was wrong, but it was a reasonable hypothesis, ‚ considering what was known about the body at the time. ‚ Other soon tested its predictions and found them incorrect. Ú Swammerdam (1669) irritated a nerve isolated from the brain. Ú Francis Glisson (1597 - 1677) use principles of physics on displacement.L ‚ For many years philosophers tried to understand the nature of the mind by logic alone. Their lack of success made it clear that more speculation is futile. ‚ ‚ ‚ The value of Descartes’s physiological model did not lie in whether it was right or wrong; rather, it served to focus the efforts of those who followed him on performing experiments. Thus, knowledge of the physiology of behavior began to accumulate.L Experimental Physiology ‚ ‚ ‚ Experimental Physiology continued One of the most important figures in the development of experimental physiology was Johannes Müller, a nineteen-century German physiologist. Müller was a forceful advocate of the application of experimental techniques to physiology.L Johannes Müller 1801 - 1858 Experimental Physiology continued Previously, the activities of most natural scientists were limited to observation and classification. ‚ Müller insisted that major advances in understanding the working of the body would be achieved only by experimentally removing or isolating animal’ organs, ‚ testing their responses to various chemicals, and otherwise altering the environment to see how the organs responded. ‚ His most important contribution to the study of the physiology of behavior was his doctrine of specific nerve energies.L Experimental Physiology continued ‚ ‚ ‚ ‚ Experimental Physiology continued Because different parts of the brain receive messages from different nerves, ‚ the brain must be functionally divided: Ú Some parts perform some functions, Ú and other parts perform others. ‚ This doctrine lead to search for locations for specific functions. Ú This issue of localization of functions or global processing is still with us in modern physiological psychology.L L Müller observed that although nerves carry the same basic message – electrical impulse – we perceive the messages of different nerves in different ways. For example: Ú messages carried by the optic nerves produce sensations of visual images Ú a those carried by the auditory nerves produce the sensation of sounds. Ú How can different sensations arise from the same basic message? The answer is that the message occur in different channels. Ú The portion of the brain that receives messages from the optic nerves interprets the activity as visual stimulation, Ú even if the nerves are actually stimulated mechanically.L Evolution ‚ ‚ Another important antecedent of physiological psychology is the work of the British biologist Charles Darwin. ‚ Darwin formulated the principle of natural selection, which revolutionized biology.L Evolution continued Evolution continued ‚ ‚ ‚ ‚ ‚ ‚ Charles Darwin L ‚ Evolution continued There are four factors essential for the Theory of Evolution: Ú Variability within members of the same species Ú Traits and characteristics are inherited. Ú Survival to the stage of reproduction (and may be longer?)(Survival of the Fittest) Ú Sexual selection ‚ Through the process of evolution, one set of organisms can have descendants after many generations that bear little resemblance to their ancestors. Ú For example, the avian species evolved from reptiles. Ú Cetacean species (porpoise & whales) evolved from land mammals.L ‚ ‚ ‚ ‚ All of Darwin’s scientific observations were concerned with the physical traits of animals. Ú On the Origin of Species by Means of Natural Selection (1859) However, he did not restrict his theory of evolution to explaining physical characteristics. He also believed that: Ú behavioral characteristics, Ú emotional expression < The Expressions of the Emotions in Man and Animals (1877) Ú and intelligence < The Decent of Man and Selection in Relation to Sex (1871) Can evolve in the same way that physical traits evolve.L This process is called evolution through natural selection.L Evolution continued Darwin proposed that evolution was responsible for the appearance of new species ‚ And saw no reason that unique human characteristics could not have developed from other types of organisms in the same way. ‚ He believed in the continuity of species that included human beings. ‚ One species may simply have taken a different course of evolution than another. ‚ The evidence for continuity of species provides a strong rational for the study of animals as a way to give insight into human beings.L ‚ Evolution continued ‚ Darwin noted that there are individuals differences with in the members of the same species. If these differences produce favorable effects that permit the individual to reproduce more successfully, some of the individual’s offspring will inherit the favorable characteristics and will themselves produce more offspring. This process is repeated over and over again across generations, with the results that more and more members of a group of animals will have the particular traits that promote survival in their environment. Functionalism ‚ ‚ ‚ Darwin other contribution is functionalism. The concept that all structures or traits serve or had served in the past a function. In another words, an organism’s characteristics – its structure, its coloration, its behaviors – have functional significance. Ú Eagles have strong talons and sharp beaks because they permit the birds to catch and eat prey. Ú Caterpillars that eat green leaves are themselves green because this color makes it difficult for birds to see them against their usual background.L Functionalism continued ‚ ‚ ‚ ‚ Contribution of Modern Psychology ‚ To understand the physiological basis of various behavior, we must first understand the significance of these behaviors. We must therefore understand something about the natural history of the species being studied ‚ ‚ so that the behavior can be seen in context.L ‚ ‚ Contribution of Modern Psychology The field of physiological psychology grew out of psychology. Indeed, the first textbook of psychology, written by Wilhelm Wundt in the late 19th century was titled: Ú Principles of Physiological Psychology The modern history of investigating the physiology of behavior has been written by psychologist who have combined the methods of: Ú experimental psychology Ú with the methods of experimental physiology and have applied them to the issues that concern psychologist.L Contribution of Modern Psychology continued Thus, we have studied: Ú perceptual processes Ú control of movement Ú sleep and waking Ú reproductive behavior Ú aggressive behavior Ú ingestive behavior Ú learning Ú and communication ‚ In recent years we have begun to study Ú the physiology of pathological conditions, such as mental disorders.L ‚ Wilhelm Wundt L The Goal of Research ‚ ‚ ‚ ‚ ‚ ‚ The goal of all scientists is to explain the phenomena they study. But what do we mean by “explain?” Scientific explanation takes two forms: Ú generalization Ú and reduction. Most psychologist deal with generalization. They explain particular instances of behavior as examples of general laws, which they deduce from their experiments.L The Goal of Research continued ‚ ‚ ‚ ‚ For example: Ú most psychologist would explain pathologically strong fears of dogs as an example of classical conditioning. Ú John B. Watson – Little Albert study Most physiologist deal with reduction. They explain phenomena in terms of simpler phenomena. For example: Ú they may explain the movement of a muscle in terms of the changes in the membrane of muscle cells, Ú the entry of particular chemicals Ú and the interaction among protein molecules within the cells.L The Goal of Research continued ‚ ‚ ‚ ‚ ‚ The task of the physiological psychologist is to explain behavior in physiological terms. But physiological psychologists cannot simply be reductionists. It is not enough to observe behaviors and correlate them with physiological events that occur at the same time. Identical behaviors may occur for different reasons and thus may be initiated by different physiological mechanisms. Therefore, we must understand “psychologically” why a particular behavior occurs before we can understand what physiological events made it occur.L The Goal of Research continued ‚ For example: Ú mice, like many other mammals, often build nests. Ú Behavioral observations show that mice will build nests under two conditions: < when the air temperature is low < and when the animal is pregnant. Ú A nonpregnant mouse will not build a nest if the weather is warm, Ú whereas a pregnant mouse will build one regardless of the temperature. ‚ The same behavior occurs for different reasons Ú it should not be surprising that these behaviors are initiated by different physiological mechanisms, < one involving changes in the level of various hormones in the animal’s blood, < the other involving nerve cells that detect temperature changes.L The Goal of Research continued ‚ ‚ ‚ ‚ Sometimes, physiological mechanisms can tell us something about psychological processes. This relationship is particularly true of complex phenomena such as: Ú language Ú memory Ú and mood which are poorly understood psychologically. For example: Ú Phineas Gage (mid 1800's) had an iron rod pass through is forebrain. Afterwards he was unable to carry out plans (impulsive). Ú H. M. bilateral removal of the hippocampus was unable to learn anything new.L The Goal of Research continued In practice, the research efforts of physiological psychologists involve both form of explanation Ú generalization Ú and reduction. ‚ Ideas for experiments are stimulated by the investigator’s knowledge both of psychological generalizations about behavior and of physiological mechanisms. ‚ A good physiological psychologist must be both a good psychologist and a good physiologists.M ‚