Physiological Influences on the Development of Psychology

1
Physiological Influences on the Development of
Psychology

• Reflex actionMarshall Hall (17901857)
• Luigi Galvani (17371798) and Allesandro Volta
  (17451827nerves activated by electricity

2
Nerve Functioning

• Bell-Magendie law
• Dorsal roots of spinal nervessensory, ventral
  roots motor
• Johannes Müller (18011858)
• Specific energies
• Nerves convey only one type of sensation

3
Hermann Ludwig von Helmholtz (18211894)

• Mechanist as opposed to vitalist
• Conservation of force
• Speed of neural impulse
• Perception
• YoungHelmholtz theory of color vision
• Trichromaticred, green, blue
• Ewald Hering (18341918) opponent
  processred/green, yellow/blue
• Both apply
• Place theory of audition
• Depth perception and unconscious inference
• Importance of learning
• Active mind

4
Phrenology and Localization

• Localizationspecific functions localized in the
  brain
• Franz Joseph Gall (17581828)
• Bumps on skull indicate brain development

5
Ablation

• Pierre Flourens (17941867)
• Ablated brain tissue
• Found functions in broad areas
• Cerebellumcoordination
• Cerebruminitiation of action
• No localization within areas
• Neural plasticity
• Phineas Gage 1848
• Change in personality
• Damage to frontal lobe

6
Localization

• Language
• Pierre Paul Broca (18241880)
• Tan (1861) and expressive aphasia
• Left frontal lobe
• Carl Wernicke (18481904)
• 1874 receptive aphasia
• Damage to left temporal lobe
• Electrical brain stimulation
• Mapping motor cortex
• Gustav Fritsch (18381927) Eduard Hitzig
  (18381907)1870
• Sir David Ferrier (18431928)

7
Psychophysics

• Measuring sensation
• Relationship between stimulus intensity and
  sensation
• Ernst Weber (17951878)
• Two point threshold
• Just noticeable difference (JND)
• Webers lawJND change/stimulusconstant
• Weber fraction

8
Gustav Theodor Fechner (18011887)

• Depression cured by insight of panpsychsim
• Stimulus ? nervous system ? sensation
• Conservation of energy
• Steps should be proportional
• Outer psychophysicsrelationship between stimulus
  and sensation
• Inner psychophysicsrelationship between nervous
  system and sensation

9
Fechners Law

• Measure sensation in JND units
• Geometric, if JND .25
• 1, 1.25(1.251), 1.5625(1.25.251.25), 1.9531
  1.5625(.251.5625)
• Fechners law S k log R
• Sensation constant log stimulus intensity
• True for intermediate range of intensity
• Methods to determine difference threshold
• Limits
• Average error
• Constant stimuli