Post on 13-Dec-2015
Chapter 3:
Physiological Influences on Psychology
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
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
20 years later…
Luigi Galvani (1737 – 1798) Suggested that the nerve impulse is electrical By mid 19th century accepted as fact
Early physiology
Early 1800s: Sensory and
motor information travels in separate pathways
i.e., info is only sent in one direction
Early physiology
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
http://tangibleinteraction.files.wordpress.com/2007/05/senses-lowres.jpg
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
http://www.uh.edu/engines/phrenologicalchart.jpg
Research on the nervous system
Pierre Flourens (1794-1867) Extirpation: Lesion a given part of an animal’s brain
and observe the resulting behavior changes.
Research on brain functions
•Cerebrum: Higher mental processes:
•Midbrain: Visual and auditory reflexes
•Cerebellum: Coordination
•Medulla: Heartbeat, respiration
Paul Broca (1824-1880) Clinical method: examine damaged
brain structures in humans after death Broca’s area:
the speech center in the 3rd frontal convolution of the left hemisphere of the cerebral cortex
when damaged, person could not produce speech
Research on brain functions
Electrical stimulation: pass a weak electrical current into animal’s brain to see motor responses
Research on brain functions
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.
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
Importance of physiologists
Hermann von Helmholtz (1821– 1894)
The Beginnings of Experimental Psychology
http://www.mrcophth.com/Historyofophthalmology/indirect.jpg
Neural impulse
Vision
Audition
Gustax Fechner (1801 – 1887) Relative intensities
Absolute threshold
Differential threshold
The Beginnings of Experimental Psychology
method of limits
Ernst Weber (1795 – 1878) Just Noticeable Differences
The Beginnings of Experimental Psychology
Ernst Weber (1795 – 1878) Two-point thresholds:
Test in which two different points were stimulated on a person’s 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
The Beginnings of Experimental Psychology
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
British empiricists Subject matter: study mind and behavior
German physiologists Methods: experimentation
General zeitgeist: encouraged melding of philosophy and physiology
The formal founding of psychology