Physiological Roots of Psychology

Introduction

  • Early scientists

    • Bell-Magendie Law

    • Hermann von Helmholtz

    • Christine Ladd-Franklin

  • Studies of the Brain

    • Phreonology

    • Phineas Gage

    • David Ferrier

  • Language and Brain

    • Aphasia

  • The Neuron

The Roots of Psychology

  • Philosophical conclusions → observation, logic, intuition

  • Physiological conclusions → observation, logic, experimentation

  • Physiological research leads to…

    • Sensation + perception

    • Language

    • Cognition

  • Descartes view → hollow tubes carried info from sense receptors to brain

  • Charles Bell (1774)

    • Using rabbits, he learned about…

      • Sensory nerves that enters one part of a spinal cord

      • Motor nerves that leave another part of a spinal cord

    • Different nerves have different functions

    • Different body structures have different mental functions

  • François Magendie (1783)

    • Discovered similar results to Bell, unaware of what Bell already found

    • Bell-Magendie Law

      • There are sensory and motor nerves

The Eye

  • Retina’s are the layer of receptor cells covering the back of the eye

  • Fovea’s are the central part of the retina that only contains cones

    • Outside of fovea are rods and cones

  • Rods are used for vision at night

  • Cones are used for vision during the day, color perception, and visual acuity

  • Hermann von Helmholtz (1821)

    • Asked “How fast does signal travel down the nerve”

      • Participants would press a button when they sense stimulus on their legs

      • Longer nerves had longer response time, vice versa with shorter nerves

      • Nerve impulse speed was determined to be 43 meters per second

  • Trichromatic Theory of Color Vision

    • Young-Helmholtz Theory

    • Newton noticed that when white light passed through a prism, a range of colors would appear

    • Different wavelengths were perceived as different colors

    • Physical → wavelengths

    • Psychological → colors

  • 3 different types of cones in retinas respond to different wavelengths

  • Color perception is determined by combined activity of receptors

  • S - M - L

    • Small, medium, large wavelengths

Helmholtz in Perspective

  • Discovered nerve impulse speed and Trichromatic Theory of Color Vision

  • Never considered himself as a psychologist

  • Brought various fields closer together

    • Physics

    • Physiology

    • Psychology

  • Influenced psychophysics and Wilhelm Wundt

Christine Ladd-Franklin (1847)

  • Worked with Helmholtz

  • Developed theory of visual perception based on evolution

  • Compared animals and humans

  • Animals were sometimes color-blind and some used night vision + movement to survive

  • Explain peripheral (1st) + foveal (2nd) vision

    • Peripheral vision was outside of the fovea, has rods, black and white color perception, and movement perception (see at night)

    • Foveal vision involves fovea, cones, color perception (RGB) and visual acuity

Franz Joseph Gall (1758)

  • Personality based on skull bumps

  • People with good memory tend to have large eyes

  • Collected data that developed a map of the brain and personalities

  • Phrenology

    • Skull bumps reveal mental abilities

    • Personality is reduced to 42 functions

Johann Spurzheim

  • Worked with Gall and popularized phrenology due to…

    • Gall’s reputation

    • Offered objective, measurable study of mind

    • Offered practice information

Problems with Phrenology

  • Impossible to reduce personality to 42 factors

  • Arguments were circular

    • Mr. Teller was a thief
      (Because of bumps on ears?)
      (Bumps lead to theft so Mr. Teller is a thief??)

  • Skull thickness doesn’t correspond to abilities

  • It’s important though because it localized mental functions

Phineas Gage

  • Frontal lobes were severed from his brain due to a pole piercing his head

  • Frontal lobes lay behind the forehead and includes the motor cortex

    • Used for speaking, muscle movements, decision-making, and regulating emotions

David Ferrier

  • Used electrical stimulation that localize sensory functions

  • Parietal Lobe → Touch

  • Occipital Love → Vision

  • Temporal Love → Hearing

Pierre-Paul Broca (1824)

  • Surgeon who criticized brain localization

  • Patient Tan

    • Transferred into Broca’s hospital

    • Only said “tan”

    • Understood spoken utterances

    • Tan’s mouth and vocal chords worked just fine

    • Died while an autopsy was being performed on him with a large cavity in the left frontal love

  • Observed other patients with similar symptoms and damage

  • Broca’s Aphasia

    • Language disorder caused by damage to Broca’s area (left frontal lobe)

    • Symptoms included difficulty producing speech and the inability to use function words (agrammatism)

    • Could still understand speech

Carl Wernicke (1848)

  • German neurologist who discovered the brain area in charge of speech comprehension

  • Wernicke’s Aphasia

    • Caused by damage to Wernicke’s Area (left temporal lobe)

    • Symptoms included difficulty understanding speech, with fluent speech that doesn’t make sense (paragrammatic speech)

    • Could still produce speech

Camillo Golgi (1843)

  • Exposed brain tissue to chemicals and learned about basic units of the brain

  • Saw neurons for the first time

    • Neurons are a whole interconnected network

Santiago Ramón y Cajal (1852)

  • Said neurons are separate and distinct units

  • Terminal branches and dendrites don’t touch

  • Came up with Neural Synapse

    • Small gap between neurons