A Brief History of Psychology I
from Descartes to Wundt
The Two Roots of Scientific Psychology
- Philosophy -- the mother of all sciences
- Physiology -- the study of the functioning of the
Although we could begin our history as far back in time as the ancient Greek philosophers (ca 300 BC),
we will actually start with one man, living in France in the first half of the 17th century, who
embodied both roots of scientific psychology: Rene Descartes.
- The Body as a Machine
- The Reflex Arc
- Stimulus leads to response via a chain of physical
causes and effects that runs from sensory receptors through the
central nervous system (brain and spinal cord) and back out again
to the muscles.
- In Descartes' proposal, the stimulus pulled on tiny wires
running up the nerves to the brain. These tugs popped open little
valves in the brain, allowing animal spirits (cerebral-spinal fluid)
to enter the hollow nerve-tubes leading to the appropriate muscles.
The fluid inflated the muscles, causing them to shorten and moving the
limb, producing the response.
- This particular conception proved to be
incorrect, but the basic conception of stimulus leading to response via a
physical mechanism was a great advance over magical thinking.
- Interactive Dualism
- Descartes assumed that all of animal behavior could be
explained in terms of chains of stimulus-response reflexes.
The animals were assumed to have no mind, consciousness, or ability
- In this conception, the animal's behavior is fully determined
by its machinery, leaving no room for the exercise of free will.
- Descartes assumed that in humans, some behavior was similarly
produced by reflex mechanisms. However, he believed that humans
could also act voluntarily, of their own free will. Thus, in his
model of the human being, he included an additional element not
found in his model of the animal: the soul. The general idea that
the human being consists of two distinct entities, body and soul,
is known as dualism.
- The soul was assumed to receive sensory information by means
of vibrations in the "animal spirits" that were conveyed to the
conarium (pineal gland) in the brain. It could then initiate
voluntary actions by moving the conarium so as to direct the
animal spirits down the appropriate nerve-tubes to the muscles.
- Because sensory experience could be conveyed to the soul (via the
conarium) and movements initiated by the soul (again via the conarium),
this particular version of dualism is referred to as interactive
dualism. The body and soul are separate but interact, or
affect each other, in the brain (specifically at the conarium).
- It is important to note that Descartes gave the
soul only the ability to reason, decide, and initiate voluntary action. He
suggested that other properties of mind, such as sensation, memory, and
emotion, were products of the mechanisms of the brain.
- Descartes' Rationalism
- Descartes was trained in the scholastic tradition,
which held that all that man was meant to know had already been
recorded in the writings of church theologans and the ancient
Greek and Roman philosophers. Thus, if you wanted the truth about
some matter, you simply looked it up in some ancient manuscript.
- Sometimes, however, different sources seemed to conflict. It
was the job of the scholastic to use logical argument to reconcile
the differences, which were assumed to be only apparent, not real
differences, as God could not contradict himself, and these works
were assumed to represent God's Truth.
- By Descartes' time, some scholars were beginning to question
this idea. His own investigations convinced Descartes that those
old Greek philosophers were only too human, and just as capable of
making mistakes as anyone else. Thus, you could not trust their
writings to provide absolute truth. Relying on such authorities
for the truth about a matter is called the method of
- Dissatisfied with the method of authority, Descartes searched
for a method that would be guaranteed to give true answers to
certain philosophical questions. Finally, he found a method that
satisfied him. We call it the rational method, or
- Rationalism begins with a search for self-evident truths,
statements that must be true, because assuming them to be false
leads to a logical contradiction. For example, if I am thinking,
then I must exist. (cogito, ergo sum, I think, therefore I am.)
- Such must-be-true statements can then be used as assumptions,
from which one can deduce (using deductive logic) conclusions that
must also be true. Assumption: I exist. Assumption: That which
exists must have been created. Conclusion: A Creator (God) must
- The use of deduction here is important, because if
the assumptions are true, and one does not make a logical mistake, then
deduction yields a conclusion that must also be true.
As we will be learning, science is based on a combination of authority, induction from
observations, and deduction. Because scientific theories are developed based on empirical
observations and induction, we can never be certain that a given theory is true -- only that
it does or does not do a good job of explaining and predicting those phenomena with which it
deals. In the history of science, even some highly confirmed theories (e.g., Newton's mechanics)
have ultimately had to be replaced when new data conflicted with theoretical predictions.
- Although Descartes often relied on his senses for information about
the physical world, he did not fully trust them to provide absolute truth:
After all, the senses can lie (consider illusions!). However, Francis Bacon
believed that it is only through the senses that we can come to know anything
about the workings of the physical universe. The idea that all such knowledge
ultimately must come from observation is called empiricism.
- Bacon suggested that by making repeated, careful observations of physical
phenomena, eventually one would be able to perceive the regularities -- what leads
to what, under what conditions. These regularities would provide the basis for
formulating universal laws that describe how the universe works.
- Although Bacon admitted that individual observations could be in error, he
believed that this limitation could be overcome by having multiple observers
independently observe the same phenomena. It would be unlikely that all would be
subject to the same illusions or delusions. The agreement of independent observers
would establish the reliability of the observations.
- This empirical method makes use of induction, in which observation of
specific cases leads to the formulation of general principles which are then assumed
to apply universally, not just to those cases on which the priinciples were originally
- Unfortunately, unlike deduction, induction is not guaranteed to produce true
conclusions. Further observations that conform to a general principle can only
support it; they can never prove that the general principle is true. However, the
principle can be proven false by a singlecounterexample. For example, observation
of thousands of white swans supports the general principle that all swans are white.
The more confirming evidence one obtains, the more confidence one may have that the
principle is true. Yet only a single example of a black swan will make the
John Locke and the British Empiricists
- No, it's not a 60's British Rock Band!
- John Locke was a Scottish philosopher who believed that the mind at birth is a tablula rosa,
or blank tablet, on which experience writes. For Locke, even the newborn's sensory experiences would
consist of a confusing mass of raw, primitive sensations, making no sense. Everything the person
comes to know and to understand, Locke asserted, must arise solely through the person's experience with
world around him or her. We can classify Locke in this regard as an extreme empiricist -- all knowledge
comes from experience. (In contrast, Bacon was only talking about how we adults can discover scientific
- The opposite view, that at least some of our knowledge is inborn, present at birth, is called
nativism . Descartes, for example, believed that we are born with at least some knowledge
about the physical universe, including an understanding of certain principles of geometry [!] and the
concept of God. (The degree to which any characteristic is determined by one's inheritance versus the
influence of one's environment was later described by Francis Galton the question of nature versus
nurture. It appears, for example, in the debate concerning to degree to which one's intelligence is
open to improvement through learning.)
- Locke did not address the question of how one got from a newborn infant, incapable even of making
sense of its own raw sensations, to a mature adult, capable of understanding all sorts of complex
concepts, even abstract ones like justice. The job of explaining how this happens was taken up by a
series of British philosophers spanning the 17th to 19th centuries, who with Locke have come to be
known as the British Empiricists.
- The British Empiricists proposed the following theory to explain all this:
- simple sensations (like redness or roundness) give rise to simple ideas in the mind.
- When simple ideas occur together in the mind, they tend to become associated, or
linked together so that, when one idea comes to mind, so do the others associated with it.
- These associated ideas may form a complex idea in
the mind. For example, the complex idea of a brick is made up of the simple
ideas of redness, roughness, heaviness, and rectangularity, which have been
experienced together repeatedly when viewing bricks.
Wilhelm Wundt: The Founding of Psychology as a Science
- Wundt worked as a professor during the later portion of the 19th century at the University
of Leipsig in Leipsig, Germany and had interests in both physiology and philosophy. Possessing an
intimate knowledge of experimental method as a result of his physiological training and a keen interest in
the conscious mind, Wundt was in an ideal position to attempt the separation of psychology (the study
of the psyche or mind) from philosophy by making psychology a scientific discipline.
- He founded the first laboratory in experimental psychology at the University of Leipsig in 1979.
Today we date the founding of the science of psychology to this event.
- His early investigations included the use of introspection (a technique in which you attempt
to observe and record the contents of your own mind inder various carefully controlled conditions),
as well as controlled experiments in which the data were derived from measurement of objective
behavior. In his experiments on mental chronography, for example, subjects' reaction times to the
occurence of a stimulus were used to estimate the duration of a mental process.
- Wundt presented his findings in public lectures and
soon had people packing the hall to hear about the latest theories or
experiments. Soon many others were setting up their own laboratories in
experimental psychology and taking up the new science.