Early Developments in
Physiology and the
Rise of Experimental
Psychology
Chapter 8
Early Interest in Physiology
500 B.C. Alcmaeon: first(?) dissections
15th century: Leonardo Da Vinci
-dissections despite ...
Individual Differences
 1795 David Kinnebrook, a research assistant of
Nevil Maskelyne, was to assess the precise
time th...
Discrepancy Between Objective and
Subjective Reality
 Discrepancies between a physical event and a
person’s perception of...
Bell-Magendie Law
 Bell-Magendie Law: There are two
types of nerves: sensory nerves
carrying impulses from the sense
rece...
Doctrine of Specific Nerve
Energies
Johannes Müller
 Born in Koblenz, Germany
 Doctorate from University of Bonn (rememb...
Doctrine of Specific Nerve Energies
Johannes Müller
 Doctrine of Specific Nerve Energies:
Each sensory nerve, no matter h...
Doctrine of Specific Nerve Energies
Johannes Müller
Adequate Stimulation
 All the sense organs are not equally
receptive ...
Doctrine of Specific Nerve Energies
Johannes Müller
We are Conscious of Sensations, not
Physical Reality
 Accepted idea
o...
Hermann von Helmholtz
 Born in Potsdam
 Mediocre student, though he spent
his spare time reading science.
 Father could...
Hermann von Helmholtz
Helmholtz’s Stand Against Vitalism
 Vitalism: The belief that life cannot be
explained solely as th...
Hermann von Helmholtz
Principle of Conservation of Energy
 Principle of Conservation of Energy: The energy
within a syste...
Hermann von Helmholtz
Rate of Nerve Conduction
 Johannes Müller had maintained that
nerve conduction was instant.
 Helmh...
Hermann von Helmholtz
Theory of Perception
 Sensation: The rudimentary mental experience
caused when sense receptors are ...
Hermann von Helmholtz
Theory of Perception
 Previous experience intervenes and makes a
sensation into a perception.
 An ...
Hermann von Helmholtz
Theory of Color Vision
 Newton had discovered that pure orange
wavelengths were indistinguishable f...
Hermann von Helmholtz
Theory of Color Vision
Hermann von Helmholtz
Theory of Auditory Perception
 The ear also has multiple
receptors, literally thousands.
 Resonanc...
Hermann von Helmholtz
Helmholtz’s Contributions
 Though the mind is active, sensations put all
the contents in the mind.
...
Ewald Hering
 Received medical degree from
University of Leipzig.
 Worked with Joseph Breuer.
 Took Jan Purkinje’s job ...
Ewald Hering
Space Perception
 When stimulated, each point on the
retina provides three types of
information about the st...
Ewald Hering
Theory of Color Vision
 Unexplained by the Young-Helmholtz
theory of color vision, mixing red/green
or blue/...
Ewald Hering
Theory of Color Vision
 Opponent Process Theory: Three receptors in
eye, but each responds in two ways.
 On...
Christine Ladd-Franklin
 Graduated from Vassar.
 Completed requirements for doctorate in
mathematics from Johns Hopkins ...
Christine Ladd-Franklin
 Proposed color vision theory based on
evolution.
 Motion detection is most primitive form of
vi...
Early Research on Brain Functioning
 Physiognomy: The attempt to
determine a person's character by
analyzing his or her f...
Early Research on Brain Functioning
Cesare Lombroso
 Criminality is inherited and the born criminal can
be identified by ...
Early Research on Brain Functioning
Cesare Lombroso
Early Research on Brain Functioning
Phrenology
Franz Joseph Gall
 Faculties of the mind act on
and transform sensory
info...
Early Research on Brain Functioning
Phrenology
Franz Joseph Gall
 Phrenology: The examination of the bumps and
depression...
Early Research on Brain Functioning
Phrenology
Franz Joseph Gall
 In the introduction to his main work The Anatomy and
Ph...
Early Research on Brain Functioning
Phrenology
The Popularity of Phrenology
 The Physiognomical System of Drs. Gall and
S...
Early Research on Brain Functioning
Phrenology
The Popularity of Phrenology
 The Lavery electric
phrenometer was
invented...
Was Phrenology that far off?
 Modern studies using MRI imaging have shown that brain
size correlates with IQ (r = 0.35) a...
Early Research on Brain Functioning
Jean Pierre Flourens
 Used the method of extirpation, or
ablation, in brain research....
Early Research on Brain Functioning
Jean Pierre Flourens
 Flourens concluded that though there was
some localization, con...
Early Research on Brain Functioning
Paul Broca
 Clinical Method: The technique that
Broca used. It involves first determi...
Early Research on Brain Functioning
Carl Wernicke
 Wernicke's Area: The area on the left temporal
lobe of the cortex asso...
Phineas Gage (unintentional contributor)
•Railroad construction gang foreman
•Good natured, well liked, hardworking
•Had s...
Early Research on Brain
Functioning
Gustav Fritsch and Eduard Hitzig
 Discovered localization of
motor areas in the corte...
Early Research on Brain Functioning
David Ferrier
 Created a “map” of the motor cortex
using monkeys.
 Proposed the monk...
Early Research on Brain Functioning
Electrical Stimulation of the Human Brain
 Roberts Bartholow
 Took advantage of a “c...
The Rise of Experimental Psychology
 Perceptions were triggered by brain processes
which were themselves triggered sensat...
The Rise of Experimental Psychology
Ernst Heinrich Weber
 Obtained doctorate from University of Leipzig
and taught there ...
The Rise of Experimental Psychology
Ernst Heinrich Weber
Weber’s Work on Touch
 Two-point Threshold: The smallest distanc...
The Rise of Experimental Psychology
Ernst Heinrich Weber
Weber’s Work on Kinesthesis
 Just Noticeable Difference (jnd): T...
The Rise of Experimental Psychology
Ernst Heinrich Weber
Judgments are Relative
 The jnd is a constant fraction of the st...
The Rise of Experimental Psychology
Gustav Theodor Fechner
 Obtained medical degree from University of Leipzig.
 Shifted...
The Rise of Experimental Psychology
Gustav Theodor Fechner
The Adventures of Dr. Mises
 In addition to Fechner the scient...
The Rise of Experimental Psychology
Gustav Theodor Fechner
Psychophysics
 Fechner wanted to solve the mind/body problem i...
The Rise of Experimental Psychology
Gustav Theodor Fechner
Psychophysics
Weber’s Law
 R = Reiz, the German word for stimu...
The Rise of Experimental Psychology
Gustav Theodor Fechner
Absolute Threshold
 Absolute Threshold: The smallest amount of...
The Rise of Experimental Psychology
Gustav Theodor Fechner
Absolute Threshold
 Vision-We can see 1 candle 30 miles away -...
The Rise of Experimental Psychology
Gustav Theodor Fechner
The jnd as a Unit of Sensation
 The absolute threshold was use...
Electric Shock Very Small
Pitch .003 = 1/333
Deep Pressure .013 = 1/77
Visual Brightness .016 = 1/62
Weight .050 = 1/20
Lo...
The Rise of Experimental Psychology
Gustav Theodor Fechner
Psychophysical Methods
 Method of Limits: A stimulus is presen...
The Rise of Experimental Psychology
Gustav Theodor Fechner
Psychophysical Methods
 Method of Constant Stimuli: A stimulus...
The Rise of Experimental Psychology
Gustav Theodor Fechner
Psychophysical Methods
 Method of Adjustment: An observer adju...
The Rise of Experimental Psychology
Gustav Theodor Fechner
Fechner’s Contributions
 Created psychophysics
 Created exper...
Empiricists:
laws, observation,
rigid methodology,
sensory experience
Rationalists
Theory, active mind,
organizing princip...
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Early Developments in Physiology

  1. 1. Early Developments in Physiology and the Rise of Experimental Psychology Chapter 8
  2. 2. Early Interest in Physiology 500 B.C. Alcmaeon: first(?) dissections 15th century: Leonardo Da Vinci -dissections despite papal ban 16th century: Michelangelo -Sistine Chapel -Dissections 16th-17th century Descartes: -Comparative animal dissections -Where does the mind and body interact? -Most philosophers had their own version of dualism 17th & 18th centuries -European Wars-- Chance to study head trauma -Executions: smiles & winks?
  3. 3. Individual Differences  1795 David Kinnebrook, a research assistant of Nevil Maskelyne, was to assess the precise time that a star crossed the crosshairs of a telescope. He was consistently ½ s different from his advisor. He was fired.  Reaction Time: The period of time between presentation of and response to a stimulus.  Personal Equations: Mathematical formulae used to correct for differences in reaction time among observers.
  4. 4. Discrepancy Between Objective and Subjective Reality  Discrepancies between a physical event and a person’s perception of it was of great concern to natural scientists who viewed their jobs as accurately describing and explaining the physical world.  The question of interest to the early scientists was “How do empirical sense impressions come to be represented in consciousness?”  Physiology provided the link between mental philosophy and the science of psychology.  The discrepancy made a science of psychology almost inevitable.
  5. 5. Bell-Magendie Law  Bell-Magendie Law: There are two types of nerves: sensory nerves carrying impulses from the sense receptors to the brain and motor nerves carrying impulses from the brain to the muscles and glands of the body.
  6. 6. Doctrine of Specific Nerve Energies Johannes Müller  Born in Koblenz, Germany  Doctorate from University of Bonn (remember, the beer drinking students despised by Nietzsche?)  Was chair of newly created physiology department at the University of Berlin  Creation of the department signaled acceptance of physiology as science.  Handbuch der Physiologie des Menschen (1833)
  7. 7. Doctrine of Specific Nerve Energies Johannes Müller  Doctrine of Specific Nerve Energies: Each sensory nerve, no matter how it is stimulated, releases an energy specific to that nerve.  Thus light, pressure, or mechanical stimulation acting on the retina and optic nerve invariably produces luminous impressions.
  8. 8. Doctrine of Specific Nerve Energies Johannes Müller Adequate Stimulation  All the sense organs are not equally receptive to all types of stimulation.  Each of the sense organs is maximally sensitive to a certain type of stimulation (specific irritability).  Adequate Stimulation: Stimulation to which a sense modality is maximally sensitive.
  9. 9. Doctrine of Specific Nerve Energies Johannes Müller We are Conscious of Sensations, not Physical Reality  Accepted idea of Kant’s categories of thought.  Instead though, the sensory systems always modify the sensations before we perceive them.
  10. 10. Hermann von Helmholtz  Born in Potsdam  Mediocre student, though he spent his spare time reading science.  Father could not afford to pay for scientific training.  Interested in natural sciences, but found a program for free medical school if he served eight years as an army surgeon.  Studied under Johannes Müller
  11. 11. Hermann von Helmholtz Helmholtz’s Stand Against Vitalism  Vitalism: The belief that life cannot be explained solely as the interaction of physical and chemical forces.  Johannes Müller was a vitalist  Materialism: The belief that there is nothing mysterious about life and assumed that it could be explained in terms of physical and chemical processes.  No reason to exclude the study of life from the realm of science.
  12. 12. Hermann von Helmholtz Principle of Conservation of Energy  Principle of Conservation of Energy: The energy within a system is constant; therefore, it cannot be added to or subtracted from but only transformed from one form to another.  Applies to living organisms as well.  The energy from food and oxygen will equal the energy expended by muscles and organs.  Clearly a materialistic statement!
  13. 13. Hermann von Helmholtz Rate of Nerve Conduction  Johannes Müller had maintained that nerve conduction was instant.  Helmholtz felt nothing was outside the realm of science.  He isolated a nerve leading to a frog’s leg muscle. • He stimulated the nerve at various points and measured how long for the muscle to respond. • Concluded nerve conduction occurs at 27.4 meters per second.
  14. 14. Hermann von Helmholtz Theory of Perception  Sensation: The rudimentary mental experience caused when sense receptors are stimulated by an environmental stimulus.  Perception: According to Helmholtz, the mental experience arising when sensations are embellished by the recollection of past experiences.  Unconscious Inference: According to Helmholtz, the process by which the remnants of past experience are added to sensations, thereby converting them into perceptions.
  15. 15. Hermann von Helmholtz Theory of Perception  Previous experience intervenes and makes a sensation into a perception.  An empirical theory of perception.  The innate categories of thought proposed by Kant were actually derived from experience.  The axioms of geometry are not innate, they are a product of the sensations we’ve had.  If the world were different, and we therefore had different sensations, the axioms would be different.  Individuals who had been blind since birth who acquired sight needed to learn to perceive.
  16. 16. Hermann von Helmholtz Theory of Color Vision  Newton had discovered that pure orange wavelengths were indistinguishable from orange created by mixing red and yellow.  The property of color cannot be in the wavelengths themselves.  Young-Helmholtz Theory of Color Vision: Separate receptor systems on the retina are responsive to each of the three primary colors: red, green, and blue-violet. Also called the trichromatic theory.  An extension of the doctrine of specific nerve energies. Not just a single nerve energy for vision, but three types of receptors on the retina.
  17. 17. Hermann von Helmholtz Theory of Color Vision
  18. 18. Hermann von Helmholtz Theory of Auditory Perception  The ear also has multiple receptors, literally thousands.  Resonance Place Theory of Auditory Perception: The tiny fibers on the basilar membrane of the inner ear are stimulated by different frequencies of sound. The shorter the fiber, the higher the frequency to which it responds.
  19. 19. Hermann von Helmholtz Helmholtz’s Contributions  Though the mind is active, sensations put all the contents in the mind.  Nerve transmission is not instantaneous.  We can scientifically study internal processes.  Though the correspondence between the external and internal world is poor, it is caused by properties of the sensory organs and unconscious inferences.  He brought chemistry, physiology, and psychology together.
  20. 20. Ewald Hering  Received medical degree from University of Leipzig.  Worked with Joseph Breuer.  Took Jan Purkinje’s job at the University of Prague.  Purkinje Shift: As twilight approaches, hues that correspond to short wavelengths such as violet and blue appear brighter than hues corresponding to longer wavelengths such as yellow or red. • Hints at the phenomenon of negative after images.
  21. 21. Ewald Hering Space Perception  When stimulated, each point on the retina provides three types of information about the stimulus: height, left-right position, and depth.  Similar to Kant’s categories of thought, but an innate characteristic of the eye.
  22. 22. Ewald Hering Theory of Color Vision  Unexplained by the Young-Helmholtz theory of color vision, mixing red/green or blue/yellow or black/white makes gray.  Similarly, if you stare at red, then look away, you see a green afterimage (ditto for BY).  If a color blind person is unable to see red, then they cannot see green either (same with BY).
  23. 23. Ewald Hering Theory of Color Vision  Opponent Process Theory: Three receptors in eye, but each responds in two ways.  One type responds to RG, one to BY, one the BW  R, Y, and W cause a tearing down (catabolic process) and G, B, and B cause a building up (anabolic process).  If the opponent colors are seen simultaneously, then gray results.
  24. 24. Christine Ladd-Franklin  Graduated from Vassar.  Completed requirements for doctorate in mathematics from Johns Hopkins University, but denied the doctorate due to her gender.  Given honorary doctorate by Vassar  Eventually given doctorate from Johns Hopkins.  Studied in Germany under Helmholtz and Georg Muller (where Hering’s theory was supported).
  25. 25. Christine Ladd-Franklin  Proposed color vision theory based on evolution.  Motion detection is most primitive form of vision.  Color detection is more modern. • Within color vision, BW vision most primitive. • Then comes BY, since it evolved earlier, it is less likely to be faulty. • Then comes RG, the newest form is the one most likely to be problematic.
  26. 26. Early Research on Brain Functioning  Physiognomy: The attempt to determine a person's character by analyzing his or her facial features, bodily structure, and habitual patterns of posture and movement.
  27. 27. Early Research on Brain Functioning Cesare Lombroso  Criminality is inherited and the born criminal can be identified by physical defects which confirm the criminal is a savage.  Large jaws, forward projection of jaw, Low sloping forehead  High cheekbones, flattened or upturned nose  Handle-shaped ears  Hawk-like noses or fleshy lips.  Hard Shifty eyes, scanty beard or baldness  Insensitivity to pain, long arms
  28. 28. Early Research on Brain Functioning Cesare Lombroso
  29. 29. Early Research on Brain Functioning Phrenology Franz Joseph Gall  Faculties of the mind act on and transform sensory information.  The faculties do not exist to the same extent in all people.  The faculties are located in specific areas.  If a faculty is well developed, the brain will push the skull.
  30. 30. Early Research on Brain Functioning Phrenology Franz Joseph Gall  Phrenology: The examination of the bumps and depressions on the skull in order to determine the strengths and weaknesses of various mental faculties.  Developed out of the notion of faculty psychology.
  31. 31. Early Research on Brain Functioning Phrenology Franz Joseph Gall  In the introduction to his main work The Anatomy and Physiology of the Nervous System in General, and of the Brain in Particular, Gall makes the following statement in regard to the principles on which he based his doctrine:  That moral and intellectual faculties are innate  That their exercise or manifestation depends on organization  That the brain is the organ of all the propensities, sentiments and faculties  That the brain is composed of many particular organs as there are propensities, sentiments and faculties which differ essentially from each other.
  32. 32. Early Research on Brain Functioning Phrenology The Popularity of Phrenology  The Physiognomical System of Drs. Gall and Spurzheim (1815)  Phrenology provided a possible objective science of the mind.  Phrenology produced useful predictive information about people (Formal Discipline).
  33. 33. Early Research on Brain Functioning Phrenology The Popularity of Phrenology  The Lavery electric phrenometer was invented to increase precision in measuring bumps on the head.  Phrenology used the phrase “Know thyself” to promote.
  34. 34. Was Phrenology that far off?  Modern studies using MRI imaging have shown that brain size correlates with IQ (r = 0.35) among adults. A study on twins showed that frontal gray matter volume was correlated with g and highly heritable. A related study has reported that the correlation between brain size (reported to have a heritability of 0.85) and g is 0.4, and that correlation is mediated entirely by genetic factors.  A study involving 307 children (age between six to nineteen) measuring the size of brain structures using magnetic resonance imaging (MRI) and measuring verbal and non- verbal abilities has been conducted (Shaw et al, 2006). The study has indicated that there is a relationship between IQ and the structure of the cortex - the characteristic change being the group with the superior IQ scores starts with thinner cortex in the early age then becomes thicker than average by the late teens.
  35. 35. Early Research on Brain Functioning Jean Pierre Flourens  Used the method of extirpation, or ablation, in brain research.  Destroy a part of the brain, then make note of behavior change.  Flourens assumed that the brains of lower animals was similar to the brain of humans.
  36. 36. Early Research on Brain Functioning Jean Pierre Flourens  Flourens concluded that though there was some localization, contrary to the phrenologists, most brain functions require interrelatedness.  Animals sometimes regained lost functions following ablations.  Other brain areas had the ability to take over for the severed area.
  37. 37. Early Research on Brain Functioning Paul Broca  Clinical Method: The technique that Broca used. It involves first determining a behavior disorder in a living patient and then, after the patient had died, locating the part of the brain responsible for the behavior disorder.  Broca's Area: The speech area on the left frontal lobe of the cortex (the inferior frontal gyrus).
  38. 38. Early Research on Brain Functioning Carl Wernicke  Wernicke's Area: The area on the left temporal lobe of the cortex associated with speech comprehension.  Though Broca’s and Wernicke’s areas supported the phrenologist’s basic contention of localization of brain functions, these functions were not found where phrenologists had said they would be.
  39. 39. Phineas Gage (unintentional contributor) •Railroad construction gang foreman •Good natured, well liked, hardworking •Had severe head injury (in 1848) •Completely changed personality •“Gage was no longer Gage” •Frontal lobes damage: •unreliable, distracted, lack foresight •Died 12 years later in 1860 Early Research on Brain Functioning Phineas Gage
  40. 40. Early Research on Brain Functioning Gustav Fritsch and Eduard Hitzig  Discovered localization of motor areas in the cortex  Stimulate an area electrically and parts of the body reliably moved  The parts that moved were the opposite to the side stimulated.
  41. 41. Early Research on Brain Functioning David Ferrier  Created a “map” of the motor cortex using monkeys.  Proposed the monkey map = human map  Discovered the sensory areas of the cortex.  Researchers after him discovered visual and auditory areas.
  42. 42. Early Research on Brain Functioning Electrical Stimulation of the Human Brain  Roberts Bartholow  Took advantage of a “clinical opportunity”  Mary Rafferty, a 30 yr old domestic worker was admitted to the hospital for a small ulcer on her scalp. The skull had worn away exposing a 2 in. area.
  43. 43. The Rise of Experimental Psychology  Perceptions were triggered by brain processes which were themselves triggered sensations.  How are the domains of mental sensations and sensory processes related?  A science of psychology was impossible unless consciousness could be measured as objectively as the physical world.
  44. 44. The Rise of Experimental Psychology Ernst Heinrich Weber  Obtained doctorate from University of Leipzig and taught there until retirement.  Interested in the senses of touch and kinesthesis (The sensations caused by muscular activity).  With his brother Eduard Friedrich Weber he discovered inhibitory power of the vagus nerve.  With another brother, W. E. Weber, he made studies of acoustics and wave motion.
  45. 45. The Rise of Experimental Psychology Ernst Heinrich Weber Weber’s Work on Touch  Two-point Threshold: The smallest distance between two points of stimulation at which the two points are experienced as two points rather than one.  He used a compass-like device to simultaneously apply pressure to two points on the skin.  On Touch: Anatomical and Physiological Notes (1834) provided charts of the entire body in regards to the two-point threshold.
  46. 46. The Rise of Experimental Psychology Ernst Heinrich Weber Weber’s Work on Kinesthesis  Just Noticeable Difference (jnd): The sensation that results if a change in stimulus intensity exceeds the differential threshold.
  47. 47. The Rise of Experimental Psychology Ernst Heinrich Weber Judgments are Relative  The jnd is a constant fraction of the standard weight.  For lifted weights it is about 1/40, for non- lifted weights it is about 1/30  Weber's Law: Just noticeable differences correspond to a constant proportion of a standard stimulus.
  48. 48. The Rise of Experimental Psychology Gustav Theodor Fechner  Obtained medical degree from University of Leipzig.  Shifted from medicine to mathematics and physics.  Published an article on properties of electrical currents.  Made professor of physics at University of Leipzig  Had interest in the mind/body relationship.  Consciousness cannot be separated from material things.  Panpsychism: The belief that everything in the universe experiences consciousness.
  49. 49. The Rise of Experimental Psychology Gustav Theodor Fechner The Adventures of Dr. Mises  In addition to Fechner the scientist, there was Fechner the philosopher, spiritualist, and mystic.  Wrote 14 books under pseudonym Dr. Mises.  Proof that the Moon is made of Iodine (1821)  The Comparative Anatomy of Angels (1825)  The Little Book of Life after Death (1836)  Nanna, or Concerning the Mental Life of Plants (1848)  Always expressed view of universe as living and conscious.
  50. 50. The Rise of Experimental Psychology Gustav Theodor Fechner Psychophysics  Fechner wanted to solve the mind/body problem in a way that would satisfy materialists of his day.  A systematic relationship between bodily and mental experience could be demonstrated if a person was asked to report changes in sensations as a physical stimulus was systematically varied.  Speculated that physical stimuli would have to vary geometrically in order for sensations to vary arithmetically.  Psychophysics: The systematic study of the relationship between physical and psychological events.
  51. 51. The Rise of Experimental Psychology Gustav Theodor Fechner Psychophysics Weber’s Law  R = Reiz, the German word for stimulus, the standard stimulus.  DR = The minimum change in R that could be detected.  k = constant (as seen earlier, k = 1/40 for lifted weights) k R R  D
  52. 52. The Rise of Experimental Psychology Gustav Theodor Fechner Absolute Threshold  Absolute Threshold: The smallest amount of stimulation that can be detected by an organism.
  53. 53. The Rise of Experimental Psychology Gustav Theodor Fechner Absolute Threshold  Vision-We can see 1 candle 30 miles away - (pretty low threshold!).  Audition–We can hear a watch tick 20 feet away.  Taste-We can taste 1 tsp. of sugar in 2 gallons of water.  Smell-We can smell 1 drop of perfume within a 3 room apartment.  Touch-We can feel the sensation of a bee wing dropped from 1 cm above your back.
  54. 54. The Rise of Experimental Psychology Gustav Theodor Fechner The jnd as a Unit of Sensation  The absolute threshold was useful, but only provided a single point of connection between the physical world and the psychological world.  Differential Threshold: The amount that stimulation needs to change before a difference in that stimulation can be detected.  Given a geometric increase in the level of stimulus, there will be an arithmetical increase in the level of sensation.  S = k log R
  55. 55. Electric Shock Very Small Pitch .003 = 1/333 Deep Pressure .013 = 1/77 Visual Brightness .016 = 1/62 Weight .050 = 1/20 Loudness .088 = 1/11 Smell, Rubber .104 = 1/10 Cutaneous Pressure .136 = 1/7 Taste, saltiness .200 = 1/5 The Rise of Experimental Psychology Gustav Theodor Fechner Estimates of Weber Constants
  56. 56. The Rise of Experimental Psychology Gustav Theodor Fechner Psychophysical Methods  Method of Limits: A stimulus is presented at varying intensities along with a standard (constant) stimulus, to determine the range of intensities judged to be the same as the standard. a.k.a. method of just noticeable differences
  57. 57. The Rise of Experimental Psychology Gustav Theodor Fechner Psychophysical Methods  Method of Constant Stimuli: A stimulus is presented at different intensities along with a standard stimulus, and the observer reports if it appears to be greater than, less than, or equal to the standard. a.k.a. method of right and wrong cases
  58. 58. The Rise of Experimental Psychology Gustav Theodor Fechner Psychophysical Methods  Method of Adjustment: An observer adjusts a variable stimulus until it appears to be equal to a standard stimulus. a.k.a. method of average error
  59. 59. The Rise of Experimental Psychology Gustav Theodor Fechner Fechner’s Contributions  Created psychophysics  Created experimental esthetics  Quantify reactions to works of art to discover why one artwork is better than another.  Predict the “success” of new works!  It is possible to measure mental events and relate them to physical ones.
  60. 60. Empiricists: laws, observation, rigid methodology, sensory experience Rationalists Theory, active mind, organizing principles, mental experience, Physiologists experiments on people determinants of thought and action, data & PROOF! THE RISE OF EXPERIMENTAL PSYCHOLOGY!! - experimentally linking physical & psychological worlds!

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