Psy 421: Systems and Theories of Psychology

Chapter 6—Nineteenth Century physiological psychology and psychophysics.

 Reflex action
Whytt (1714-1756) demonstrated that the spinal cord was necessary and sufficient for many automatic reflexes in 1751. He was one of several researchers who independently demonstrated spinal reflexes in frogs and reflexes in man; these he claimed depend on a sentient principle
Prochaska (1784) reflexes are automatic and not voluntary or conscious
Galvani (1791) electricity in nerves and muscles. Demonstrated kick in frogs legs by connecting legs to two rods of different metals
Marshall Hall (1790-1857) distinguished four kinds of bodily movement--a) voluntary (cerebral), b) respiratory (medulla), c) involuntary movement (direct muscular stimulation), d) reflexes (spinal)
Pfluger (1853) All nervous action is conscious; even when reflex is produced by a spinal preparation.

Nerve functions
1811-1822: Bell-Magendie law—Different nerves have different functions. Bell (1774-1842) and Magendie (1783-1855) independently discovered sensory (dorsal) and motor (ventral) nerves.
1833: Johannes Müller—Handbook of physiology. Suggested the idea of specific nerve energies
1845: Students of Müller (Helmholtz, Ludwig, Brucke, du Bois-Reymond)--pact against vitalism. All theoretical explanation in physiological systems should be explained by the principles of physics and chemistry.

Helmholtz (1821-1894)

  1. Very influential scientist: perhaps most important of 19th century
  2. 1850—Conservation of energy in physiological systems
  3. measured speed of the nervous impulse <100 ft/sec
  4. Theories of hearing and vision
  5. Specific fiber energies for all senses
  6. Empiricist--unconscious inference (Data: Distorting lenses, seeing individuals blind at birth)
Localization of Brain function

Gall (1758-1828)

  1. Studied brain anatomy
  2. Faculty psychology
  3. Phrenology (localization (and strength) of faculties from bumps on the head)
  4. Used phrenology as diagnostic tool
  5. Phrenology led to the scientific study of localization of function in the brain
Flourens (1794-1867)
  1. extirpation method--six large functional areas of nervous system

    2. cerebral cortex (perception, intelligence, and will)
  2. cerebellum (coordination of movements
  3. medulla oblongata (vital center)
  4. Corpora quadrigemina (supports seeing)
  5. spinal cord (conduction)
  6. nerves (excitation)
  7. Common action and propre action
  8. More physiological landmarks
Broca (1861)--localization of speech center in cortex
Fritsch & Hitzig (1870)--motor cortex
Ferrier (1876)--specific movements mapped to specific cortical locations
Munk (1881) occipital lobes each control half of visual field
Cajal (1889) neuron theory

Psychophysics--One can scientifically relate conscious experience to physical stimuli
Weber (1795-1878)--just noticeable differences (jnd’s) DS/S=k
Sensitivity variations (2 pt. threshold)
Discrimination depends on background stimulus as well as the presented one

Fechner (1801-1887)

  1. Fechner’s law S=k log R

    2. (the magnitude of a sensation is proportional to the log of the magnitude of a stimulus)
  2. psychophysical methods--
  3. constant stimuli,
  4. method of limits,
  5. method of adjustment
  6. Experimental aesthetics (judgments of beauty)
  7. Panpsychism--there is consciousness in everything
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