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Physiological Psychology
PSYC370
Thomas E. Van Cantfort, Ph.D.
Introduction
Roots of Physiological Psychology
The nervous system, the final frontier.
To boldly go where no one has gone before.
‚ The human nervous system makes possible
Ú all that we can do,
Ú all that we can know,
Ú all that we can experience.
‚ Its complexity is immense,
‚ and the task of studying it and understanding it
‚ dwarfs all previous explorations our species has
undertaken.L
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Introduction
Introduction to Physiological Psychology
Roots of Physiological Psychology
Roots of Physiological Psychology
Investigation of the physiology of behavior has a long
history, with roots in
Ú philosophy
Ú biology
Ú and psychology.
‚ Philosophers have asked how we perceive and
understand reality
Biologists have devised experimental physiology, which
provides the tools we use to investigate the workings of
the body.
‚ They have also developed the framework needed to
integrate findings from diverse species:
Ú the principle of natural selection,
Ú evolution,
Ú and genetics.
‚ Psychologists have devised methods of
Ú behavioral observation and analysis
Ú and presented many of the theoretical questions that
motivated much of the research being performed
today.L
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and have posed the mind/body question, which remains
with us still.
‚ They have also devised the scientific method – a set of
rules that permits us to ask questions about the natural
world with some assurance that we receive reliable
answers.L
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Philosophical Roots of Physiological Psychology
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Philosophy (comes from the Greek meaning loving
wisdom) originally concerned itself with the basis of
human knowledge and thought.
Philosophers soon realized that in order to understand
the basis of knowledge, they must understand the nature
of reality,
Ú which led them to develop natural philosophy, the
predecessor to modern physical and biological science.
Ú In ancient times people believed that natural
phenomena were caused by animating spirits.
Ú All moving objects – animals, the wind and tides, the
sun, moon, and stars – were assumed to have spirits
that caused them to move.
< For example, stones fell when they were dropped
because their animating spirits wanted to be reunited
with Mother Earth.L
Philosophical Roots continued
As our ancestors became more sophisticated and learned
more about nature,
‚ they abandoned this approach – which we call animism – in
favor of physical explanations for inanimate moving objects.
Ú But they still used spirits to explain human behavior.
‚ From the earliest historical times people have believed they
possess souls.
Ú This belief stems from our awareness of our own
existence.
< When we think or act, we feel as if something inside us
– our mind or our soul – is thinking or deciding to act.
• This method of looking inward is called
introspection.L
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Philosophical Roots continued
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But what is the nature of the mind?
Ú We have physical bodies,
Ú equipped with muscles that move it
Ú a sensory organs such as the eyes and ears
Ú that perceive information about the world around us.
Within our bodies the nervous system plays a central
role,
Ú controlling the movements of the muscles
Ú and receiving information from the sensory organs.
Ú But what role does the mind play?
< Does it control the nervous system?
< Is it a part of the nervous system?
< Is it physical and tangible, like the rest of the body,
< or is it a spirit that will always remain hidden?
< Or is there a mind at all?L
Philosophical Roots continued
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Dualism
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Early philosophers believed that reality was divided into
two categories:
Ú the material
Ú and the spiritual.
According to this belief, humans have physical bodies
and nonphysical spirits, or souls.
Mind and body are considered to be separate; the body is
made of ordinary matter,
Ú but the mind is not.
Ú This belief is called dualism.
Ú Those who hold this belief are known as dualist.
But if the physical and spiritual aspects of our nature are
independent, as this model suggests, L
Dualism continued
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This puzzle has historically been called the mind-body
question.
Philosophers have been trying to answer it for many
centuries,
and more recently, scientists have taken up the task.
Basically, people have followed two different
approaches: dualism and monism.
As we shall see, these two approaches reflect very
different assumptions about the nature of reality.L
Dualism continued
then what is the purpose of having both,
or in what way are they related?
‚ If the body functions independently of the soul, then
what does the soul do?
‚ The concept of soul is the cornerstone of religion;
philosophers were therefore unwilling to dispense with
it.
‚ Instead, they suggested that the soul controls the body.
‚ Because the eyes and ears – the primary windows to the
soul – are located in the head,
‚ The probable location of the soul was presumed to be the
brain.L
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Dualism continued
Moreover, damage to the head can lead to
unconsciousness or paralysis,
which suggested that the soul moved the body by
controlling the operations of the brain.
In the seventeenth century (1660) the French philosopher
and mathematician René Descartes attempted to explain
how the soul could control the body.
His explanation is known as Cartesian Dualism.L
René Descartes
L
Cartesian Dualistic Model
Dualism continued
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Descartes believed that animals other than humans were
machines (a mechanistic view).
If we could understand how their parts were put
together,
we should be able to understand them completely.
According the Descartes the bodies of humans were also
machines and operated on exactly the same principles.
However, unlike other animals, we had a God-given
soul.L
Descartes identified two types of behaviors, voluntary
and involuntary behaviors.L
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Cartesian Dualistic Model continued
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Involuntary behavior according to Descartes were
elicited by external stimuli.
Ú Descartes formulated the first physiological model of
behavior.
Ú He based his model on the mechanism that activated
the statues in the grottoes of the Royal Gardens at
Versailles just west of Paris.
Ú As a young man, he was fascinated by the hidden
mechanisms that caused the statues to move and dance
when visitors stepped on hidden plates.
Ú The statues were moved by hydraulic cylinders
powered by water pressure.
Ú Descartes believed that the muscles of the body also
worked hydraulically.L
Cartesian Dualistic Model continued
Ú When
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we exert a force with our limbs, our muscle
appears to get larger.
Ú Descartes concluded that this enlargement occurs
because fluid, which he called animal spirits, is
pumped into the muscles through the nerves.
Ú When nerves are cut, liquid oozes out; hence the nerves
must be hollow.
What is the source of the fluid that gets pumped into the
muscles?
Ú According to Descartes, it was the cerebral ventricles –
the hollow, fluid-filled chambers of the brain.
Ú He concluded that the mechanism that directed the
pressurized fluid into the appropriate nerves was the
pineal gland,
Ú a small organ situated on top of the brain stem.L
Cartesian Dualistic Model continued
Ú The
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pineal gland acted like a little joystick: when it was
tilted slightly in various direction,
Ú it opened pores that permitted fluid to enter the nerves
and inflate the mucles.
Ú Because animals lacked souls, Descartes believed that
this model completely explained their behavior.
Humans, however, possessed souls as well as bodies.
Humans had voluntary behavior. That is conscious
control of behavior.
Ú The pineal gland, which controlled the movements of
the pressurized fluids through the nerves to the
muscles,
Ú provided the place for the soul to interact with the
body.L
Cartesian Dualistic Model continued
Ú The
soul received information about the world through
the body’s senses,
Ú thought about what it perceived,
Ú and made decisions about actions.
Ú When it wanted to move the body, it did so by acting
on the brain,
Ú which, in turn, moved the muscles.
Ú When the soul desired a particular action, it tilted the
pineal gland appropriately,
Ú and the muscles needed to carry out the action became
inflated.L
Cartesian Dualistic Model continued
Monism
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Descartes’s theory contains a built-in contradiction.
Ú If the soul or mind is not a part of the physical world,
Ú then it cannot exert a force that moves physical objects.
Ú Thus it cannot interact with matter.
If the soul or mind possesses material properties that
permit it to interact with the body,
then it, like the body, is physical.
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Logically, we cannot have it both ways.L
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Physiological psychologists take an empirical, practical,
and monistic approach to the study of human nature.
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Monism is the belief that reality consists of a unified
whole and, thus, that the mind is a phenomenon
produced by the working of the body.
The monist believe that once we understand how the
body works – in particular, how the nervous system
works – the mind-body problem will have been
solved.L
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Monism continued
What monist call “mind” is consequence of the
functioning of the body and its interaction with
environment.
‚ The mind is an epiphenomenon – a by product of the
brain’s activities.L
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Biological Roots of Physiological Psychology
Not all modern philosophers are monist,
and not all believe that the human mind is based on
physiological functioning.
‚ Yet scientists who study the physiology of behavior trace
their intellectual ancestry to the monistic, deterministic
school of philosophy.
‚ This school encouraged the development of natural
scientist,
‚ who first studied living organisms in the world around
them
‚ and eventually applied their techniques and principles to
the study of human behavior.L
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Biological Roots continued
Biological Roots continued
Although such early natural philosophers as Aristotle
speculated about the causes of behavior,
‚ René Descartes’s physiological model provides a good
starting place for a discussion of the biological roots of
physiological psychology.
‚ His model was wrong, but it was a reasonable
hypothesis,
‚ considering what was known about the body at the time.
‚ Other soon tested its predictions and found them
incorrect.
Ú Swammerdam (1669) irritated a nerve isolated from the
brain.
Ú Francis Glisson (1597 - 1677) use principles of physics
on displacement.L
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For many years philosophers tried to understand the
nature of the mind by logic alone.
Their lack of success made it clear that more speculation
is futile.
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The value of Descartes’s physiological model did not lie
in whether it was right or wrong;
rather, it served to focus the efforts of those who
followed him on performing experiments.
Thus, knowledge of the physiology of behavior began to
accumulate.L
Experimental Physiology
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Experimental Physiology continued
One of the most important figures in the development of
experimental physiology was Johannes Müller,
a nineteen-century German physiologist.
Müller was a forceful advocate of the application of
experimental techniques to physiology.L
Johannes Müller 1801 - 1858
Experimental Physiology continued
Previously, the activities of most natural scientists were
limited to observation and classification.
‚ Müller insisted that major advances in understanding the
working of the body would be achieved only by
experimentally removing or isolating animal’ organs,
‚ testing their responses to various chemicals, and
otherwise altering the environment to see how the organs
responded.
‚ His most important contribution to the study of the
physiology of behavior was his doctrine of specific
nerve energies.L
Experimental Physiology continued
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Experimental Physiology continued
Because different parts of the brain receive messages
from different nerves,
‚ the brain must be functionally divided:
Ú Some parts perform some functions,
Ú and other parts perform others.
‚ This doctrine lead to search for locations for specific
functions.
Ú This issue of localization of functions or global
processing is still with us in modern physiological
psychology.L
L
Müller observed that although nerves carry the same
basic message – electrical impulse – we perceive the
messages of different nerves in different ways.
For example:
Ú messages carried by the optic nerves produce
sensations of visual images
Ú a those carried by the auditory nerves produce the
sensation of sounds.
Ú How can different sensations arise from the same basic
message?
The answer is that the message occur in different
channels.
Ú The portion of the brain that receives messages from the
optic nerves interprets the activity as visual stimulation,
Ú even if the nerves are actually stimulated
mechanically.L
Evolution
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Another important antecedent of physiological
psychology is the work of the British biologist Charles
Darwin.
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Darwin formulated the principle of natural selection,
which revolutionized biology.L
Evolution continued
Evolution continued
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Charles Darwin
L
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Evolution continued
There are four factors essential for the Theory of
Evolution:
Ú Variability within members of the same species
Ú Traits and characteristics are inherited.
Ú Survival to the stage of reproduction (and may be
longer?)(Survival of the Fittest)
Ú Sexual selection
‚ Through the process of evolution, one set of organisms
can have descendants after many generations that bear
little resemblance to their ancestors.
Ú For example, the avian species evolved from reptiles.
Ú Cetacean species (porpoise & whales) evolved from
land mammals.L
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All of Darwin’s scientific observations were concerned
with the physical traits of animals.
Ú On the Origin of Species by Means of Natural Selection
(1859)
However, he did not restrict his theory of evolution to
explaining physical characteristics.
He also believed that:
Ú behavioral characteristics,
Ú emotional expression
< The Expressions of the Emotions in Man and Animals
(1877)
Ú and intelligence
< The Decent of Man and Selection in Relation to Sex (1871)
Can evolve in the same way that physical traits
evolve.L
This process is called evolution through natural
selection.L
Evolution continued
Darwin proposed that evolution was responsible for the
appearance of new species
‚ And saw no reason that unique human characteristics
could not have developed from other types of organisms
in the same way.
‚ He believed in the continuity of species that included
human beings.
‚ One species may simply have taken a different course of
evolution than another.
‚ The evidence for continuity of species provides a strong
rational for the study of animals as a way to give insight
into human beings.L
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Evolution continued
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Darwin noted that there are individuals differences with
in the members of the same species.
If these differences produce favorable effects that permit
the individual to reproduce more successfully,
some of the individual’s offspring will inherit the
favorable characteristics
and will themselves produce more offspring.
This process is repeated over and over again across
generations,
with the results that more and more members of a group
of animals will have the particular traits that promote
survival in their environment.
Functionalism
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Darwin other contribution is functionalism.
The concept that all structures or traits serve or had
served in the past a function.
In another words, an organism’s characteristics – its
structure, its coloration, its behaviors – have functional
significance.
Ú Eagles have strong talons and sharp beaks because they
permit the birds to catch and eat prey.
Ú Caterpillars that eat green leaves are themselves green
because this color makes it difficult for birds to see
them against their usual background.L
Functionalism continued
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Contribution of Modern Psychology
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To understand the physiological basis of various
behavior,
we must first understand the significance of these
behaviors.
We must therefore understand something about the
natural history of the species being studied
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so that the behavior can be seen in context.L
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Contribution of Modern Psychology
The field of physiological psychology grew out of
psychology.
Indeed, the first textbook of psychology, written by
Wilhelm Wundt in the late 19th century was titled:
Ú Principles of Physiological Psychology
The modern history of investigating the physiology of
behavior has been written by psychologist
who have combined the methods of:
Ú experimental psychology
Ú with the methods of experimental physiology
and have applied them to the issues that concern
psychologist.L
Contribution of Modern Psychology continued
Thus, we have studied:
Ú perceptual processes
Ú control of movement
Ú sleep and waking
Ú reproductive behavior
Ú aggressive behavior
Ú ingestive behavior
Ú learning
Ú and communication
‚ In recent years we have begun to study
Ú the physiology of pathological conditions, such as
mental disorders.L
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Wilhelm Wundt
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The Goal of Research
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The goal of all scientists is to explain the phenomena they
study.
But what do we mean by “explain?”
Scientific explanation takes two forms:
Ú generalization
Ú and reduction.
Most psychologist deal with generalization.
They explain particular instances of behavior as
examples of general laws,
which they deduce from their experiments.L
The Goal of Research continued
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For example:
Ú most psychologist would explain pathologically strong
fears of dogs as an example of classical conditioning.
Ú John B. Watson – Little Albert study
Most physiologist deal with reduction.
They explain phenomena in terms of simpler
phenomena.
For example:
Ú they may explain the movement of a muscle in terms of
the changes in the membrane of muscle cells,
Ú the entry of particular chemicals
Ú and the interaction among protein molecules within the
cells.L
The Goal of Research continued
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The task of the physiological psychologist is to explain
behavior in physiological terms.
But physiological psychologists cannot simply be
reductionists.
It is not enough to observe behaviors and correlate them
with physiological events that occur at the same time.
Identical behaviors may occur for different reasons and
thus may be initiated by different physiological
mechanisms.
Therefore, we must understand “psychologically” why a
particular behavior occurs before we can understand
what physiological events made it occur.L
The Goal of Research continued
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For example:
Ú mice, like many other mammals, often build nests.
Ú Behavioral observations show that mice will build nests
under two conditions:
< when the air temperature is low
< and when the animal is pregnant.
Ú A nonpregnant mouse will not build a nest if the weather is
warm,
Ú whereas a pregnant mouse will build one regardless of the
temperature.
‚ The same behavior occurs for different reasons
Ú it should not be surprising that these behaviors are initiated
by different physiological mechanisms,
< one involving changes in the level of various hormones in
the animal’s blood,
< the other involving nerve cells that detect temperature
changes.L
The Goal of Research continued
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Sometimes, physiological mechanisms can tell us
something about psychological processes.
This relationship is particularly true of complex
phenomena such as:
Ú language
Ú memory
Ú and mood
which are poorly understood psychologically.
For example:
Ú Phineas Gage (mid 1800's) had an iron rod pass
through is forebrain. Afterwards he was unable to
carry out plans (impulsive).
Ú H. M. bilateral removal of the hippocampus was
unable to learn anything new.L
The Goal of Research continued
In practice, the research efforts of physiological
psychologists involve both form of explanation
Ú generalization
Ú and reduction.
‚ Ideas for experiments are stimulated by the investigator’s
knowledge both of psychological generalizations about
behavior and of physiological mechanisms.
‚ A good physiological psychologist must be both a good
psychologist and a good physiologists.M
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