History and Systems of Psychology PSY502
IMPACT OF PHYSICAL SCIENCES ON PSYCHOLOGY
As the thinking of man went through various phases of development, psychology also underwent
developments. By the end of the 19th century and the beginning of the 20th century, the world and
particularly Europe, had witnessed three earth-shaking events in the last two hundred years. The first one
was the French revolution which had resulted in abolishment of feudalism and monarchy, setting an
example for Europe and the world to follow. This revolution had a great impact on thinking of man. On
the other hand the industrial revolution of the 18th century was another ground breaking event of the same
era. The Industrial revolution in England, Europe, America and Japan had replaced much of manual labor
with machines. New towns were established. The third event was the Soviet Revolution in Russia. In Russia
the Bolshevik party had overthrown the monarchy, ended feudalism and abolished the concept of private
property. All means of production were nationalized and owned by the state meaning that Socialism was
established in the state.
The impact of these three events was that the industrialization spread giving rise to an attitude of
encouragement of new ideas, initiative and stress on research. Keeping this brief background in view, let us
see what impact some physical sciences had on psychology by looking at the contributions of two scientists.
One of the most important scientists of the 19th century was Charles Darwin. He was born in 1809
in England. He got education there and undertook research in Botany, Zoology or Biology. Therefore,
Darwin was basically a man of physical sciences rather that psychology but as we shall see, Darwin related
his theories of physical sciences with psychology. Darwin died in 1882.
Charles Darwin traveled and conducted experiments in many parts of the world. He collected
samples of plants and observed animals. He discovered that animals in one part of the world were different
from other parts of the world, but in areas where the conditions were similar, the animals were also similar.
He noted this particularly in tortoise. Based upon his extensive research and observation he proposed that
man can be studied the same way as we can study animals.
One of the greatest contributions of Charles Darwin is that he put forward the view that life and
survival in the world requires constant struggle and battle against hostile forces. He stated that only those
organisms survive who can fight the battle and win while weak organisms perish. This is the law of the
nature. This law is called "Survival of the Fittest" which was given by Darwin in an article written by him.
Relating it to psychology, Darwin said that psychology is a study of tactics of organism for survival and
emotions are an important factor for survival of the organisms. This means that organisms use their
emotions to accomplish the task of fighting against the hostile environment and forces.
For example, when an animal shows its teeth to a predator in anger, the predator is scared. The
animal is actually expressing its emotions. The emotions may merely to scare the enemy. On the other hand,
when an animal screams or cries, it is actually calling others for help. Therefore, according to Darwin, this is
how organisms use emotions to survive in the battle of nature. Darwin was able to relate the battle for
survival in the nature with the psychology of the organism. This reflects his aim of discovering the link
between physiology and psychology.
Another contribution of Charles Darwin is he put forward the view that environment plays a
dominant role in determining the psychology of a person. This means that the environment, in which a
person lives, influences his thinking, his imagination, the way he behaves and his overall personality. This
proposition of Darwin gave rise to the nature versus nurture controversy; which means that it is quite
uncertain that whether it is the nature that shapes the thinking and behavior of a human being or it is the
bringing up that shapes it. Therefore, man's thinking is either a product of the environment that he lives in,
History and Systems of Psychology PSY502
or the training that is imparted onto him. It was later proved that there was a lot of truth in what Darwin
Another scientist belonging to the world of physical sciences whose thinking had an impact on the
development of psychology was Gustav Fechner. He was a German physicist, who was born in 1801 and
died in 1887.
Fechner is known for devising ways of measuring psychological experiences in physical terms,
called psycho-physics methods. Psycho-physics methods are methods in which Fechner proposed to
measure what a person was experiencing psychologically. The measurement was in physical terms using laws
of physics. This was one of the most important contributions of Fechner, apart from other noteworthy
In order to explain the relationship between psychological experiences and their physical
measurement, Fechner proposed the concept of "Sensory Threshold". According to Fechner, sensory
threshold is the minimum stimulation required by a sense organ to register a stimulus. This means that, to
which intensity of the stimulus the sensory organs of body would be able to acknowledge the existence of
that stimulus. For example at which level of volume, a human ear would be able to detect sound.
Fechner went on to identify the "Absolute threshold" which is a stimulus value that evokes a
response 50% of the times. This means that when a stimulus is given repeatedly for 100 times, if it evokes a
response 50 times, that is the absolute threshold.
Fechner also identified the "Differential threshold" which is the stimulus value where one stimulus
is regarded as different from another stimulus 50% of the time. This means that when two similar stimuli
are given repeatedly 100 times, the difference is noted 50 times. This is the differential threshold. Fechner
also devised the method of measuring the absolute threshold; it is called the method of minimal changes.
Because of these contributions, particularly because of his inventions of methods of measuring
psychological experience in physical terms he has been called the father of psychophysics.
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