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