Physiological Influences on Psychology

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• Chapter 3
• Physiological Influences on Psychology

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The importance of the human observer

• Measurement errors
• 1795 Maskelyne (England's royal astronomer) and
  his assistant, Kinnebrook, recorded different
  times for a star to travel from point to point

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20 years later

• Bessel reviewed the above incident
• Reasoned that the difference in times was due to
  individual differences not under personal control
• Why important?
• Cognitive processes occur over a definable time
  period
• Scientists forced to acknowledge that the
  observer is important (personal traits and
  perceptions)
• Scientists began to focus on the physiological
  processes involved in sensing and perceiving

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Early physiology

• Luigi Galvani (1737 1798)
• Suggested that the nerve impulse is electrical
• By mid 19th century accepted as fact

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Early physiology

• Early 1800s
• Sensory and motor information travels in separate
  pathways
• i.e., info is only sent in one direction

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Early physiology

• Johannes Muller (1801-1858)
• Dominant advocate of experimental method
• Specific energies of nerves doctrine
• stimulation ? specific nerve ? sensation
• Importance
• Lead to the idea that
• different areas of the brain
• have different functions
• Localization of functions

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Research on the nervous system

• Franz Josef Gall (1758-1828)
• Phrenology
• the correlation of bumps on the skull with
  personal traits
• However, Flourens showed that underlying brain
  did not follow contours of skull

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Research on brain functions

• Pierre Flourens (1794-1867)
• Extirpation Lesion a given part of an animals
  brain and observe the resulting behavior changes.

• Cerebrum Higher mental processes
• Midbrain Visual and auditory reflexes
• Cerebellum Coordination
• Medulla Heartbeat, respiration

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Research on brain functions

• Paul Broca (1824-1880)
• Clinical method examine damaged brain structures
  in humans after death
• Brocas area
• the speech center in the 3rd frontal convolution
  of the left hemisphere of the cerebral cortex
• when damaged, person could not produce speech

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Research on brain functions

• Electrical stimulation pass a weak electrical
  current into animals brain to see motor
  responses

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Research on the nervous system

• Santiago Ramón y Cajal (1852-1934)
• Discovered the direction of travel for brain and
  spinal cord nerve impulses (Nobel prize)

• Nervous system comprised a vast array of
  independent, separate nerve cells.

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Importance of physiologists

• Countered idea that psychology could never be a
  science
• by making it possible to measure mental
  experience
• with precise and elegant techniques of
  measurement.
• In other words, they revealed a way to
  investigate the mind-body relationship

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The Beginnings of Experimental Psychology

• Hermann von Helmholtz (1821 1894)

• Neural impulse
• Vision
• Audition

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The Beginnings of Experimental Psychology

• Gustax Fechner (1801 1887)
• Relative intensities
• Absolute threshold
• Differential threshold

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method of limits
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The Beginnings of Experimental Psychology

• Ernst Weber (1795 1878)
• Just Noticeable Differences

No
100 lbs
101 lbs
Yes
102 lbs
100 lbs
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The Beginnings of Experimental Psychology

• Ernst Weber (1795 1878)
• Two-point thresholds
• Test in which two different points were
  stimulated on a persons skin
• The objective was to discover how far the two
  points had to be away from each for the person to
  notice that there were two points
• First systematic experimental demonstration of
  the concept of threshold
• Also demonstrated individual differences between
  people

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Many of these physiologists were German

• Why?
• Location where physiology was firmly established
• Tendency to use inductive rather than deductive
  reasoning
• Temperament of German people
• Broader definition of science
• Greater opportunities to make a living as a
  scientist

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The formal founding of psychology

• British empiricists
• Subject matter study mind and behavior
• German physiologists
• Methods experimentation
• General zeitgeist encouraged melding of
  philosophy and physiology