psyc-375-chapter-8-physiology-and-psychophysics-textbook-notes.pdf

lOMoARcPSD|37523509 Psyc 375 Chapter 8: Physiology and Psychophysics Textbook Notes History of Psychology (Athabasca University) Scan to open on Studocu Studocu is not sponsored or endorsed by any college or university Downloaded by JENESAH HANKE ([email protected]) lOMoARcPSD|37523509 Chapter...

lOMoARcPSD|37523509 Psyc 375 Chapter 8: Physiology and Psychophysics Textbook Notes History of Psychology (Athabasca University) Scan to open on Studocu Studocu is not sponsored or endorsed by any college or university Downloaded by JENESAH HANKE ([email protected]) lOMoARcPSD|37523509 Chapter 8: Physiology and Psychophysics     Lots had been learned about the world physically and it was time to direct the scientific method toward the study of physiological mechanisms. o How do external events come to be represented in consciousness? o Everything from sense perceptions to motor reactions To look at the origins of experimental psychology, must look to early developments in other empirical sciences o Physiology, anatomy, neurology, and physics and astronomy. Objective and Subjective o Nevil Maskelyne and David Kinnebrook were setting ships clocks based on stars  Kinnebrook’s observations were half a second slower  Was relieved of his duty when he tried to fix it and it got worse.  Bessel discovered that this was not incompetence, but individual difference that caused this. o Observed systematic differences in his colleagues. o First time reaction study  People were more interested in what was true about general consciousness, not individual differences.  Individual differences were often attributed to sloppy science.  Individual differences threatened natural scientists.  Was becoming increasingly evident that things are not always what they seem on the surface when it comes to psychology.  Physical scientists were interested in how organisms interact with the world. o Looked at nerves, neural conduction, reflexes, behavior, perceptions, brain functioning and more. Bell-Magendie Law o Two main views prevailed about what nerves are.  Descartes-fibers connected sense receptors to the brain. In hollow tubes.  Hartley: Nerves send vibrations from sense receptors to the brain and from the brain to the muscle. o Charles Bell had ground breaking research on this.  Demonstrated that sensory information enters the posterior (dorsol) roots of the spinal chord, and motor nerves come from the anterior (ventral) roots.  Discovery separated nerve physiology into the study of sensory and motor functions.  Was a big discovery because it demonstrated that mental functions are mediated by different anatomical structures.  Only shared this information with his friends  Idea of this first emerged long long ago, but this was the first evidence. o Francois Magendie published similar results 11 years later without knowing about Bell’s findings.  Is now called the Bell-Magendie Law. Downloaded by JENESAH HANKE ([email protected]) lOMoARcPSD|37523509     A law of forward direction  This law also suggested separate sensory and motor parts of the brain. Doctrine of Specific Nerve Energies o Johannes Muller expanded the Bell-Magendie Law by devising the Doctrine of Specific nerve energies.  There are different types of sensory nerves that each contain a characteristic energy-when stimulated, a characteristic sensation results.  Each nerve responds in its own way and cannot respond in a different way o The nerves that sense light will always result in the sensation of seeing light.  Emil Du Bois-Reymond thought that if we cut and cross auditory and visual nerves, we would hear with our eyes and see with our ears.  Student of Muller. Adequate stimulation o Muller did not think all sense organs were equally sensitive to the same type of stimulation.  Each type of sense organs are maximally sensitive to certain stimulations. Called Adequate Stimulation  Best to trigger our eyes with light rather than pressure.  Believed that the nerves account for how clearly we sense the world- Later been determined to actually be the brain. Consciousness, Sensations, and Reality o The nervous system, not physical stimulus, determines our sensations.  We are never conscious of this world but of various sensory impulses in the brain linked to those objects.  Our knowledge of the world is limited to the information that our senses can interpret. o Muller thought he found the equivalent to Kant’s categories of thought.  The nervous system is the intermediary between physical objects and consciousness.  For Kant, sensory information is transformed by the innate categories of thought.  In both cases, sensor information is modified.  What we experience consciously is different from what is physically present.  Sensations do not exhaust mental life. o Muller was one of the greatest experimental psychologists ever.  Established world’s first institution for experimental psychology. Herman Von Helmholtz    Some think he is the Premier scientist of the 19 th century. Made contributions to physics, physiology and psychology. Was a frail child and was mediocre student o Read scientific books in free time. Downloaded by JENESAH HANKE ([email protected]) lOMoARcPSD|37523509      Bright students went to medical school free if they served the army as a surgeon for 8 years after. He did this. o Studied with Johannes Muller. Helmholtz Stand against Vitalism o Disagreed with Muller about vitalism.  Vitalists: life can not be explained but the interactions of physical and chemical process alone  Nothing mysterious about life to materialists. o Helmholtz was a materialist, Muller a vitalist.  Helmholtz sign an oath that materialism was true.  Convinced many other big people in psychology to sign the oath. Principle of the conservation of Energy o Energy is never created or lost in a system.  Wrote this in a paper while he was in the army and it was so influential that they let him go. o Appointed lecturer of anatomy at the academy of arts and the next year was appointed professor of physiology at Konigsberg. Rate of Nerve Conduction o Measured the rate of nerve conduction in frogs.  Happened quicker when the nerve was stimulated closer to the muscle rather than farther away.  Did the same thing then in people.  Showed that nerve impulses are measurable. o Abandoned studying reaction times because it was too unreliable. Theory of Perception o Believed past experience is what converts sensation into a perception.  Sensations are raw elements of conscious experience  Perceptions are sensations after they have been given meaning by past experiences. o Helmholtz relied heavily on unconscious inference.  Basically another word for schema’s. We see a chair as a chair from past experiences and the parts that make up the whole.  He didn’t like the word for this phenomena because it sounded so mysterious, but he couldn’t find a better way to describe it.  Supported this with babies who were born blind but then gained sight o Need help learning perception.  Also supported with glasses he made that distorted perception o But people adapted to the glasses, showing perceptual adaptation.  Showed how certain categories of thought came from experience.  Helmholtz and kant agreed that the perceiver transforms what the senses provide. Downloaded by JENESAH HANKE ([email protected]) lOMoARcPSD|37523509 Helmholtz never considered himself a psychologist. He thought it was too close to metaphysics. Theory of color vision o Changed a man named Young’s theory slightly and then used experimental evidence.  Young-Helmholtz Theory of Color vision  Or Trichromatic Theory o Newton showed white light through a prism was all the colours.  The property of colour is not in the wavelengths themselves, but in the observer.  People can’t distinguish between orange caused by a single orange wavelength or from wavelengths caused by mixing red and yellow. o How do we account for the lack of correspondence between physical stimuli present and the sensations they cause?  Helmholtz postulated that there are three different types of colour receptors on the retina.  These three allow us to see all the different colours.  This explained why many physical wavelengths give rise to the same colour experience. o Also explained the different types of colour blindness.  Amazed by physiological mechanisms distorting the information a person receives.  More amazed by the mismatch between physical events and the psychological sensations. Theory of Auditory Perception o The ear is not a single receptor, but a complex system of many receptors.  Thousands of different types of nerve fibers with their own specific energies.  Sensitive to different frequencies.  Short fibers respond to higher frequencies, long to low frequencies. o Process called sympathetic vibrations (tuning fork)  When the main membrane in the inner ear was removed (Basilar membrane) it is shaped like a harp.  This membrane is to hearing what the retina is to seeing.  Helmholtz also believed this happened in the middle ear too.  Combinations give us our experiences of sound.  This theory is called the resonance place theory of auditory perception. Helmholtz Contributions o Empiricist in explanations, but believed in an active mind.  Mind’s job is to create accurate representation of reality.  Different from other British empiricists because they believed in a passive mind. o    Downloaded by JENESAH HANKE ([email protected]) lOMoARcPSD|37523509 Agreed though with their belief on the origins of the content of the mind. Showed that nerve transmission is actually a slow process and not instantaneous. Showed how we understand the physical world.  What we experience is not perfect though. No mystical unscientific forces involved. His work brought together chemistry, physics, and physiology together. Paved the way for experimental psychology. Went to America and Visited William James.  Died a year later.  o o o o o o Ewald Hering        Sided with nativists Medical degree Showed that respiration was caused by receptors in the lungs. o Called the hering-Breuer reflex. Succeeded Purkinje Purkinje Thought that the phenomena of the mind is what physiologists should try to explain. o Normal and abnormal ones. Purkinje Shift= short wavelengths look brighter than longer wavelengths. Function of luminance levels. Space Perception and Color Vision o Hering thought that when stimulated, each point on the retina provides three pieces of information:  Height, left-right position, and depth. o Thought space perception was a priori like Kant. Innate in humans. o Noticed come things in color vision not fully explained by Young-Helmholtz theory  Looking away from something red give a green after-image.  Blue gives a yellow afterimage.  Red-green colour blind people can still see yellow.  Red-Green colour blind people lose both colors. Not one or the other. o Came up with a new theory  Three types of receptors on retina that can respond in two ways  Red-green, yellow-blue, and black and white. o Red yellow white cause a tearing down/ catabolic process o Green, blue, black, cause an anabolic process. o Both catabolic and anabolic being experience at the same time cause us to see gray. o If one color of a recptor is experienced, the other is depleted. Downloaded by JENESAH HANKE ([email protected]) lOMoARcPSD|37523509  Large debate happened between the two theories.  Young-Helmholtz theory is currently viewed as correct, but that there are neural processes beyond the retina that are more in line with hering’s process. Christine Ladd-Franklin    Laura Bassi thought to be the first female university professor. Christine Ladd pursued mathematics at John Hopkins university, got the requirements for a docterate but was not given it because she was a woman. Finally got it when she was 80. Became interested in psychology and was able to pursue it. o Worked under Muller (where hering’s theory of color vision was believed), then studied with Helmholtz and learned Trichromatic Theory of color vision. o Came up with her own theory based on evolutionary theory  Black and white is basic, colour came later.  Human eye carries vestiges of earlier evolutionary development  Fovea is the most evolved part of the eye and is through which we see color. Do not see color in our peripheral vision.  Peripherals are better for night vision and is more primitive.  Color vision evolved in three stages. Achromatic-blue-yellow sensitivityand then red-green sensitivity.  Explains the fragility and possibility of red-green colour blindness.  Preferred the Hering’s theory. Her theory was not in opposition to either one though and more so described the evolution.  Her view became neglected though and unpopular. Early research on Brain Functioning   At the end of the 18th century, was believed that a person’s character could be seen in their facial features, movements, and posture. o Called Physiognomy  On popular type was phrenology Phrenology o Franz Joseph Gall  Believed that faculties of the mind acted on and transformed sensory information. Made three important claims  Mental faculties do not exist to the same extent in all people  Faculties are held in specific areas of the brain  Well developed faculties create bumps of protrusions o Underdeveloped causes dips.  Faculties could be examined with the bumps on your head- called phrenology.  But the evidence he used was faulty. He generalized too much  Overall he made positive contributions to society though Downloaded by JENESAH HANKE ([email protected]) lOMoARcPSD|37523509 First to suggest a relationship between cortical development and mental functioning. o Larger, better developed cortices are associated with more intelligent behavior.  Distinguished between gray and white matter in the brain  Different cortical regions are associated with different functions. The popularity of Phrenology o Term phrenology came from Thomas Fosterand was made popular by johan Kaspar Spuzheim who brought it to English speaking countries.  Gall didn’t like the word. o Became huge because of Galls reputation and provided hope for objective, materialistic analysis of the mind.  Wanted to study men scientifically and objectively.  Appeared to offer practical information o Became big in the US and Spurzheim was a celebrity when he came.  All sorts of people came to hear him lecture – were looking for information that would later be sought in behaviorism. o Spurzheim died shortly after coming to the US. On the day of his funeral the phrenology society was created.  Lots of journals on the topic.  Anywhere from 27 (proposed by Gall) to 43 faculties shown on charts. o Formal Discipline:  Highly influential in education. Some said faculties become stronger with practice.  Mental muscle approach.  This belief in strengthening faculties is called Formal discipline.  Eventually proved false by Edward Thorndike.  Phrenology eventually rejected. o But had some use. Argued the mind and the brain are connected. o Guy named Sheldon found personality connections between different body shapes.   Pierre Flourens    By the 19th century, people knew the brain was an organ of the mind. Brain mind relationship became a focus. Goal of Pierre Flourens was to prove Phrenology wrong scientifically. o Used extirpation or ablation  Involves destroying a part of the brain and then seeing the behavioral consequences that follow.  He used dogs and pigeons. o Destroying the cerebellum disturbed coordination and equilibrium, cerebrum resulted in passivity, and the semi-circular canals caused loss of balance. Downloaded by JENESAH HANKE ([email protected]) lOMoARcPSD|37523509 There is some localization, but the cortical hemispheres function as a unit. Interrelated Some animals regained functions after the ablations- other parts fo the brain adapted. The cortex functioned as a unit. This finding silences the phrenologists in the medical community.  o o Paul Broca     Phineas Gage had an iron tamping rod go through his skull. He survived and fully recovered. o Became indulgent and indecisive and impulsive. Paul Broca also made post mortem correlations o Used a clinical method and cast doubt that the cortex acted as a single unit. o Found a lesion in a man’s brain that stopped him from talking. Impacted speech articulation and production. Called Broca’s area.  Jean-baptiste Boulilaud also determined the localization of a speech area that Broca found later.  Bouillaud had been closely related to phreneology though so Broca is credited with the finding. Carl Wernicke later discovered and area near Broca’s area that affected speech comprehension. o Called Wernicke’s area. Left temporal lobe of the cortex.  These findings hurt Flouren’s theories. But this is not where phrenologists had said speech would be located. Other aspects of Broca’s work were less interesting. o Craniometry- compare size of the brain to intelligence. No evidence found for this.  Lots of very large animals with low intelligence.  Small animals with great intelligence.  Continued to believe in this relationship despite no evidence. o To this day, there is a modest association between brain size and test scores. Don’t know why. Electrophysiology: Fritsch and Hitzig    18th century called the age of electricity. Made its way into physiology. o Galvani showed that electrical current made a frog’s leg move. o Emil Du Bois-Reymond sometimes called the father of electrophysiology. Fritsch and Hitzig stimulated the exposed cortex of a dog and discovered o The cortex is not insensitive. o When certain areas are stimulated, movement happens from the opposite side of the body. David Ferrier o Same thing as Fritcsh and Hitzig but used monkeys and iner electrical stimulation. Downloaded by JENESAH HANKE ([email protected]) lOMoARcPSD|37523509 Created a map of the motor cortex. Down to specific details such as the eyelids, ear, or singular fingers.  Then did senses. Had a large impact on scientific community.  Opened the modern era of neurosurgery. Showed there is a lot of localization to the brain.  Extended the Bell-Magendie law as sensation was more about the cortical brain stimulation that sensory nerve stimulation. Brain is like a complex switchboard.  o o o The Rise of Experimental Psychology   Big difference between what is present in the world and what is experienced psychologically. o Made Galileo conclude that psychology was impossible as a science. o Hume thought we could n=know nothing about the physical world. Now it was believed that consciousness was created by the brain and its processes, which were initiated by sense reception. o So how are conscious mental events and physiological processes of out sensory system related? Ernst Heinrich Weber      Contemporary of Muller, son of a theology professor. Third of 13 children. Was a physiologist interested in the senses of touch and kinesthesis ( Muscle sense). o Most research on sense perception had previously ben on vision and audition. Explored skin and muscle sensation. o Sense of touch is several senses. Pressure, temperature, pain. o Also muscle sense Touch and Kinesthesis o Tried to figure out how we can discriminate between two points of touch on the body.  Smallest distance between two points that can be discriminated against is called the Two-Point Threshold. o Two point threshold is different across different parts of the body.  Smallest is on the tongue (1 mm). Largest is the middle of the back (60 mm)  Believed it varied because of the arrangement of sense receptors on the different areas. His research on muscle sense/ kinesthesis was more important than touch. o Looked to determine the smallest weight that people could determine between.  Report which objects were heavier of lighter than the standard. Downloaded by JENESAH HANKE ([email protected]) lOMoARcPSD|37523509 When they were only slightly different, they were thought to be the same.  Determined Just noticeable Difference, between the standard and variable.  Can discriminate better when lifting the objects than when the objects were simply placed on one’s hands that were resting on a table. o Greater sensitivity from kinesthetic movement. Judgments are Relative, Not Absolute. o No simple one to one correspondence between what is physically present and what is psychologically experienced.  Everything is relative. o Jnd corresponds to a constant fraction of a standard stimulus : Weber’s Law.  For lifted weights: 1/40  For non lifted weights: 1/30 o First statement of a systematic relationship between physical stimulation and a psychological experience. o Fechner realized the implications of Weber’s work- possible resolution of the Mind-body problem   Gustave Theodor Fechner        His dad became the village pastor- placed a lightning rod on the church After dad died, spent nine years with uncle who was also a pastor. Studied medicine and got medical degree by 21. Interest then shifted from medicine to physics and math. Interested in the properties of electrical currents- published an article on the topic. o Became a professor of physics shortly after. o Interest shifted again to problems of sensations.  Published articles on color vision and afterimages. Nearly blinded himself while looking at the sun, had a nervous breakdown and resigned from his job. o Shifted interest to philosophy  Uncomfortable with materialism (night-view), contrasted it with Day view (mind, spirit, and consciousness.  Accepted spinoza’s double aspect view of the mind in that consciousness is as prevalent in the universe as is matter.  Consciousness cannot be separated from physical things. o Panpsychism: things that are physical are also conscious o Died at 86 and was eulogized by Wilhelm Wundt. Adventures of Dr. Mises Downloaded by JENESAH HANKE ([email protected]) lOMoARcPSD|37523509 Had a pseudonym called Dr. Mises. First appeared while he was a medical student.  Wrote some satire on the medical field.  Thought that angels were spheres and didn’t have legs because they were the perfect shape.  Wrote about the Day-view with Dr. Mises.  Described what would become Psychophysics through him. o Wrote about human life having three stages.  Darkness in the womb  Being present and conscious on earth  Moments of looking into the third stage during the second stage.  The third stage occurs after death.  Human souls merge with the supreme spirit o Fechner was always interested in spiritual phenomena.  Attended parapsychology events. Psychophysics o Physical and mental are two aspects of the dame fundamental reality.  But how do you prove this. o A systematic relationship between bodily and mental experience could be demonstrated if a person were asked to report the changes in sensations as a physical stimulus was systematically varied.  For the mental sensations to change arithmetically, the physical stimulus would have to change geometrically.  This lead to the creation of Psychophysics. o Released the book Elements of psychophysics which launched psychology as an experimental science.  The study of the relationship between physical and psychological events.  Relationship led to the expression : △R/R=k  R= Reiz= stimulus  △ R= minimum change detected in stimulation.  K= a constant = 1/40 like weber found. o Formula that shows the relationship between the mental and the physical  S=k log R  Mathematically states Fechner’s earlier insight.  As the stimulus gets larger, the magnitude of the change must become greater and greater to be detected. The JND as the unit of Sensation o Starting from zero, there would be a point at which a sensation is consciously detected.  Absolute threshold: lowest intensity at which a stimulus can be detected.  Below this you detect nothing, even if something is there.  Unnoticed sensations are called negative sensations. o   Downloaded by JENESAH HANKE ([email protected]) lOMoARcPSD|37523509 Differential threshold: continuous scale that shows how sensations above the absolute threshold vary as a level of stimulation.  How much a stimulus magnitude needs to be increased or decreased before a person can detect a difference.  Fechner’s law assumed that sensations increased in equal units as the stimulus intensity increased geometrically beyond the absolute threshold. o Thought this was the bridge between the physical and the mental.  Was accurate for middle ranges of stimulation, not accurate for high or low intensities. Psychophysical Methods. o Method of limits: one stimulus is varied and compared to a standard. o Method of Constant stimulation: pairs of stimuli presented to the subject. One stimuli is the standard and remains the same. The other varies in magnitude from one presentation to the other. o Method of adjustment: Subject has control over the variable stimulus and is instructed to adjust the magnitude to that the stimulus appears equal to the standard. Fechner’s contributions o Created a field of experimental aesthetics. o Tried to quantify reactions to works of art to see what made some art more pleasing. o Did not solve the mind-body problem  But did show that you can measure mental events and relate them to physical ones. o   Downloaded by JENESAH HANKE ([email protected])