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Experimental Design
The overarching goals of the following exercise are to demonstrate how psychology and the scientific
method can be used to address issues that interest your students, to teach them how them how the concepts
they are learning influence experimental design, and to impress on them an appreciation for the challenges
faced by experimental psychologists. Lead your class through the process of designing an experiment. Start
with a hypothesis generated through brainstorming by the class. Allowing your students to provide the
hypothesis ensures that it will interest them and that they will stay engaged. Students may start with topics
such as alien abduction, crop circles, and the Loch Ness monster. Welcome this, as it gives you a terrific
opportunity to talk about alternative explanations, existence proofs, and the fact that some topics, such as
the proof of the existence of God, remain firmly outside the boundaries of science. The scientific method is
not a panacea; it is a highly structured method for testing measurable factors and relationships. After your
class has agreed on an issue to test, lead them toward a consensus, testable hypothesis about the issue.
Once your class has clearly defined a hypothesis, lead them through a discussion of possible alternative
explanations. Challenge their hypothesis and their beliefs. Are there other possible explanations that are
more simple and more likely? What assumptions and possible biases underlie their hypothesis? How
would the hypothesis (and their assumptions and biases) generated by your class be different than
explanations put forward by people from different cultures and different times? You might want to mention
that spirit possession was a widely held explanation for mental illness until relatively recently. After listing
a number of possible alternative explanations, allow your class to suggest a very basic methodology for
testing the hypothesis and eliminating the alternative explanations. You might want to give them a head
start by suggesting the kind of data that they would need to collect to measure the variables of interest.
Depending on the hypothesis chosen and the sophistication of your class, outlining a reasonable
experiment may be a difficult process. If the class begins to show signs of overload, you can quickly switch
gears and use the exercise to demonstrate the difficulty in designing and executing well-controlled
experiments.
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BIOGRAPHICAL PROFILES
Sir Francis Galton (1822–1911)
r /> Few psychologists are credited with more firsts than Galton, the cousin of Charles Darwin. A child prodigy,
Galton could read by 2. years old and by six was reading Shakespeare for pleasure. He graduated from
Cambridge University in 1843, but never obtained a graduate degree. Because he was independently
wealthy, as were many early psychologists, Galton was free to follow his passion, and his passion led him
to measurement, first of geography and then of humans. Galton first gained fame as a cartographer for the
Royal Geographical Society on a trip to Africa. On his return to England, Galton took his cousin’s notion of
the importance of individual differences to evolution, and set about measuring these differences in humans.
Galton was the first to use questionnaires, the first to study the nature–nurture controversy, the first to use a
word-association test, the first to study twins, and the first to study intelligence testing seriously. Galton’s
work also spawned the creation of the ubiquitous correlation coefficient, r, by his student Charles
Spearman.
Edward Titchener (1867–1927)
Edward Titchener attended Oxford from 1885 to 1890, where he became interested in experimental
psychology and translated Wundt’s Principles of Physiological Psychology into English. After graduating
from Oxford, Titchener spent two years studying with Wundt in Leipzig. After receiving his Ph.D. in 1892,
Titchener took a job at Cornell University, where he remained for his entire career. While at Cornell,
Titchener developed a thriving department and became the leading exponent of structuralism in America.
Titchener adopted Wundt’s technique of introspection to the study of observable conscious events and
sought to describe the contents of mental life. Although not successful in his goal of creating a periodic table
of mental events, much like the periodic table of physical elements, Titchener exerted a profound influence
over the development of psychology in America, through both his ideas and the ambitious research
program that he led at Cornell.
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CHAPTER 2: RESEARCH METHODS IN PSYCHOLOGY
TIMELINE
Year Event
1811 Charles Bell and Francois Magendie discovered that there are two types of nerves: sensory and
motor nerves.
1827 Ludwig von Beethoven died.
1838 Johannes Müller articulated his “Doctrine of Specific Nerve Energies.”
1846 Ernst Weber derived the quantitative relationships between subjective experience and physical
stimulation, known as Weber’s Law.
1848 Marx and Engels published the Communist Manifesto.
1859 Charles Darwin published On the Origin of Species by Natural Selection, a culmination of his
research and thinking about evolution via natural selection.
1860 Gustav Fechner published Elements of Psychophysics, which outlined the experimental study of
the relationship between subjective experience and physical stimulation.
18611865
The American Civil War was fought.
1872 Claude Monet painted Impression—Sunrise, Le Havre, the painting that lent its name to the
Impressionist movement.
1885 Hermann Ebbinghaus published his empirical research on memory.
1890 William James published the Principles of Psychology, a two-volume text that became the
standard reference for psychology students.
1896 Thomas Edison invented the motion picture.
1898 Edward Thorndike conducted the first systematic experiments on animal learning.
1905 Alfred Binèt and Theodore Simon developed the first useful intelligence test.
1906 Charles Sherrington published Integrative Actions of the Nervous System, which set forth the basic
principles and terminology used today to describe the structure and function of the nervous
system.
1913 John Watson published “Psychology as the Behaviorist Views It,” sometimes referred to as the
Behaviorist Manifesto, an influential paper asserting that psychology should restrict its subject
matter to observable behavior.
19141918
World War I was fought.
1928 Ivan Pavlov published Lectures on Conditioned Reflexes, a survey of his research on classical
conditioning.
1938 B. F. Skinner published Behavior of Organism: An Experimental Analysis, which outlined the basic
principles of operant conditioning.
19391945
World War II was fought.
1946 The American Psychological Association was reorganized to include practitioner psychologists,
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as well as research psychologists.
1950 William Estes published “Toward a Statistical Theory of Learning,” a classic paper outlining a
mathematical approach to learning.
1957 Noam Chomsky published Syntactic Structures, inaugurating an era of productive collaboration
between psychologists and linguists. Psycholinguistics soon became a flourishing field of
psychology.
1957 Herbert Simon published Administrative Behavior: A Study of Decision-Making Processes in
Administrative Organizations, detailing the dynamics of decision making under conditions of
uncertainty.
1962 David Hubel and Thorston Weisel published their research on how specific features of visual
stimuli excite specific neurons in the visual cortex.
1981 Roger Sperry received the Nobel Prize for his pioneering work on the split-brain phenomenon.
SUGGESTIONS FOR FURTHER READINGS
Bordens, K. S., & Abbott, B. B. (1991). Research Design and Methods: A Process Approach, 2nd Edition. Mountain
View, CA: Mayfield. Applies the research process to both theoretical and practical problems.
Graziano, A. M., & Raulin, M. L. (1989). Research Methods: A Process of Inquiry. New York: Harper Collins
Publishers.
Keppel, G. (1991). Design and Analysis: A Researcher’s Handbook, 3rd Edition. Englewood Cliffs, New Jersey:
Prentice Hall.
Stanovich, K. E. (1996). How to Think Straight about Psychology, 4th Edition. Glenview, IL: Scott, Foresman. A
scholarly yet entertaining account of the necessity of using the scientific method in psychology and of its
application to everyday life, filled with great examples to use in lectures.
DISCOVERING PSYCHOLOGY
PROGRAM 2: UNDERSTANDING RESEARCH
Overview
An examination of the scientific method and the ways in which data are collected and applied– in the lab and in the field –
with an emphasis on sharpening critical thinking regarding research findings.
Key Issues
The power of belief, the placebo effect, the double blind procedure, the scientific method and
psychology, and lie detection.
New Interviews
Christina Maslach takes an in-depth look at applied research.
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CHAPTER 2: RESEARCH METHODS IN PSYCHOLOGY
FILMS AND VIDEOS
Flatland (1965). Contemporary Films, 12 minutes
When a “square” from the two-dimensional world of Flatland tries to convince others of the existence of
a third dimension, he is harshly persecuted. This animated film illustrates beautifully the scientific
ideals of objectivity and openness to change.
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PSYCHOLOGY AND LIFE
CHAPTER 3
The Biological Bases of Behavior
LEARNING OBJECTIVES
On completion of this chapter, students should be able to:
1. Understand how biology contributes to the creation of unique individuals
2. Appreciate the complex interplay among the brain, mind, behavior, and environment that creates
the unique experience of being human
3. Understand the nature versus nurture and the heredity versus environment controversies
4. Explain Darwin’s Theory of Natural Selection and its relevance and importance to the field of
psychology
5. Offer examples when given the statement, “Genes do not code for destinies; they code for potential”
6. Describe the various methods for exploring the functions of the nervous system
7. Identify the structures and functions of the central nervous system, the peripheral nervous system,
and the autonomic nervous system
8. Describe the major structures of the brain, and identify their function
9. Explicate the basic functions of the glands in the endocrine system, and explain the role of
neurotransmitters
CHAPTER OUTLINE
I. Heredity and Behavior
A. End points of Causal Explanation
1. Nature versus Nurture
2. Heredity versus Environment
B. Evolution and Natural Selection
1. Natural Selection: Fundamental assumption of psychology
a) Charles Darwin published The Origin of the Species in 1859
b) Survival of the fittest: Only those organisms most adapted to the
environment survive
2. Genotypes: A specific genetic structure
3. Phenotypes: Outward appearance and repertory of behaviors
4. Genotype and the environment interact to yield a particular phenotype
C. Human Evolution
1. Human evolution favored two adaptations: Bipedalism and Encephalization
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CHAPTER3: THE BIOLOGICAL BASES OF BEHAVIOR
a) Bipedalism: the ability to walk upright
b) Encephalization: increases in brain size
2. Language: A third critical evolutionary milestone for humans
a) Language is the basis of cultural evolution–the ability of cultures to
respond adaptively, through learning, to environmental change. Works
much more quickly than genetic evolution.
D. Variation in the Human Genotype
1. Basic Genetics
a) Genes: Organized packets of DNA that contain the instructions for the
production of proteins
b) Genes are found on rod like structures known as chromosomes. Humans
contain 46 chromosomes, 23 from the mother and 23 from the father.
c) Estimates of the number of genes in the human genome range from 30,000
to 150,000
d) The X and Y sex chromosomes determine sex. One X comes from the
mother, and either an X or a Y comes from the father. XX = female. XY =
male.
2. Genes and Behavior: the interaction of psychology and genetics
a) Biology (genes) is (are) not destiny
b) Genes only determine the range of effects that the environment can have in
shaping phenotype and behavior
c) The person that you become is jointly determined by genes and the
environment, by nature and nurture
3. Sociobiology focuses on evolutionary explanations for social behavior and social
systems of humans and other animal species
II.Biology and Behavior
A. Early Explanations of Behavior
1. Rene Descartes argued that human physiology could be studied empirically, that
humans are just an animal machine, and that human action is a mechanical
response to the environment
2. Sir Charles Sherrington provided evidence for Descartes’ ideas and suggested that
the human nervous system involves both excitatory and inhibitory processes
3. Santiago Ramón y Cajal detected the physical gaps between adjacent neurons
4. Donald Hebb proposed that the brain is not merely a mass of tissue but a highly
integrated series of structures, or cell assemblies, that perform specific functions
5. Neuroscience is one of the most rapidly growing areas of research today
B. Eavesdropping on the Brain
1. Broca’s Area: The region of the brain that translates thoughts into speech
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2. Producing brain lesions
a) Not done on humans for obvious ethical reasons
b) Helpful in treating some neurological disorders such as epilepsy
3. Electrical stimulation
a) Walter Hess found that sleep, sexual arousal, anxiety, and terror could be
turned on and off by electrically stimulating specific areas of the brain
4. Recording and imaging brain activity
a) Electroencephalogram (EEG) records large, integrated patterns of brain
electrical activity
b) Positron-Emission Tomography (PET) scans construct a dynamic portrait
of the brain by detecting how radioactive (but safe) substances are
processed in the brain during different cognitive and behavioral activities
c) Magnetic Resonance Imaging (MRI) uses pulses of energy to cause atoms
to align with a magnetic field. Special radio receivers then monitor the rate
at which atoms decay from alignment once the energy pulse is complete.
Computers analyze this information to create dynamic models of brain
activity.
C. The Nervous System
1. Comprised of two major divisions
a) The central nervous system (CNS), comprised of all the neurons in the
brain and spinal cord
b) The peripheral nervous system (PNS), comprised of all the neurons
forming the nerve fibers that connect the CNS to the body
2. The Central Nervous System (CNS)
a) Integrates and coordinates all bodily functions, processes all incoming
neural messages, and sends commands to different parts of the body
b) Relies on PNS for information from sensory receptors
3. The Peripheral Nervous System (PNS)
a) Provides the CNS with sensory information and relays commands from
the brain to the body’s organs and muscles
b) Composed of two subdivisions
(1) The Somatic Nervous System (SNS), which regulates the actions
of skeletal muscles
(2) The Autonomic Nervous System (ANS), which sustains basic life
processes, further divided into two subdivisions:
(i) The Sympathetic Division governs response to
emergencies
(ii) The Parasympathetic Division governs routine operation
of internal bodily functions
D. Brain Structures and Their Functions
1. The brain is the most important component of the CNS and is composed of three
layers: the brain stem, the limbic system, and the cerebrum
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CHAPTER3: THE BIOLOGICAL BASES OF BEHAVIOR
2. The Brain Stem
a) The Medulla, located at the top of the spinal cord, controls breathing, blood
pressure, and the heart
b) The Pons, located directly above the Medulla, provides inputs to other
structures of the brain stem and to the cerebellum
c) The Reticular Formation, located between the Medulla and Pons, arouses
the cerebral cortex to new stimulation and keeps the brain alert even
during sleep
d) The Thalamus, located above the Pons, receives input from the reticular
formation and channels incoming sensory information to the appropriate
area of the cerebral cortex
e) The Cerebellum, located attached to the brain stem at the base of the skull,
coordinates bodily movements and plays a role in some types of learning
3. The Limbic System mediates motivated behaviors, emotional states, and memory
processes and is composed of three structures:
a) The Hippocampus plays an important role in the acquisition of explicit
memories–memories that you are aware of retrieving
b) The Amygdala plays a role in emotional control and the formation of
emotional memories, especially those related to threat and danger
c) The Hypothalamus plays a role in maintaining homeostasis such as body
weight, temperature, and the endocrine system
4. The Cerebrum regulates higher emotional and cognitive functions
a) The Cerebral Cortex is the thin outer layer of the cerebrum
b) The cerebrum is also divided into two symmetrical halves, the cerebral
hemispheres
c) The two cerebral hemispheres are connected by a thick mass of nerve fibers
called the corpus callosum, which relays messages between hemispheres
d) Grooves in the cerebrum, called the Central Sulcus and the Lateral Fissure,
help divide each cerebral hemisphere into four lobes
e) The Frontal lobe is located at the front of the cerebrum and is involved in
motor control and cognitive activities such as planning, decision making,
and goal setting
f) The Parietal lobe is located at the top of the cerebrum and is responsible for
the sensations of touch, pain, and temperature
g) The Occipital lobe is located at the back of the cerebrum and is responsible
for visual processing
h) The Temporal lobe is located at the side of the cerebrum and is responsible
for auditory processing
i) The hemispheres and lobes of the brain do not function independently,
rather they work as an integrated unit similar to an orchestra
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j) The Motor Cortex, located in front of the central sulcus, controls movement
of the body’s voluntary muscles
k) The Somatosensory Cortex, located behind the central sulcus in the parietal
lobes, processes information about temperature, touch, body position, and
pain
l) The Auditory Cortex, located in the temporal lobes, processes auditory
information
m) The Visual Cortex, located in the occipital lobes, processes visual
information
n) The Association Cortex, which includes all of the cortex that is unlabeled,
works to interpret and integrate information from many parts of the brain
5. Hemispheric Lateralization
a) Roger Sperry and Michael Gazzaniga devised situations that could allow
visual information to be presented separately to each hemisphere.
b) Information from the right visual field goes to the left hemisphere, and
information from the left visual field goes to the right hemisphere
c) Speech may be the most highly lateralized of all brain functions. For most
people, speech is a left hemisphere function.
d) The left hemisphere tends to be more analytical, processing information bit
by bit
e) The right hemisphere tends to be more holistic, processing information in
global patterns
f) There may be gender differences in lateralization. When making
r /> judgments, the left hemispheres of males showed more activity, while both
hemispheres of females showed activity
E. The Endocrine System
1. A highly complex communication system comprised of a network of glands that
supplements the work of the nervous system
a) Hormones–“the messengers of life”–are chemicals secreted by the glands of
the endocrine system. They influence sexual development, physical
growth, moods, arousal level, immune functioning, and metabolism rate.
2. The Hypothalamus serves as an intermediary between the endocrine system and the
nervous system. Messages from the brain cause the hypothalamus to release
hormones to the pituitary gland.
3. The Pituitary Gland, the “master gland,” secretes about ten different types of
hormones, which influence the functioning of all other endocrine system glands, and
influences growth
a) In males, the pituitary gland activates secretion of testosterone, which leads
to sperm production
b) In females, the pituitary gland activates secretion of estrogen, which is
essential to the release of eggs from the ovaries
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III. The Nervous System in Action
A. The Neuron
1. The neuron is a cell specialized to receive, process, and transmit information to other
cells. There are at least 200 different types of neurons, which are typically comprised
of dendrites, soma, axon, and terminal buttons.
a) Dendrites are branched fibers that extend outward from the body of the
neuron and that receive messages from other neurons
b) The Soma, or cell body, integrates information received by the dendrites
and passes it along to the axon
c) The Axon is a single extended fiber that conducts information to terminal
buttons
d) Terminal buttons are bulblike structures that secrete neurotransmitters
which influence other neurons
2. There are three major classes of neurons: sensory neurons, motor neurons, and
interneurons
a) Sensory neurons carry messages from sense receptors toward the CNS
b) Motor neurons carry messages from the CNS to the muscles and glands
c) Interneurons carry messages between different neurons
3. Glia cells, derived from the Greek word for “glue,” outnumber neurons in the brain by
about five or ten to one and perform three primary functions: housekeeping,
insulation, and protection of the brain
a) Development: Glia cells help guide newborn neurons to appropriate
locations in the brain
b) Housekeeping: Glia cells clean up after neurons die and absorb excess
neurotransmitters
c) Insulation: Glia cells form a myelin sheath around the axon of some types
of neurons, greatly increasing the conduction speed of the axon
d) Protection: Glia cells form a blood-brain barrier that prevents toxins from
reaching the brain
B. Action Potentials
1. Neurons send messages in an all-or-none fashion through action potentials traveling
down the axon, and they receive messages in the form of graded potentials through
the dendrites
a) Excitatory input increases the likelihood that a neuron will fire
b) Inhibitory input decreases the likelihood that a neuron will fire
c) Graded Potentials are generated by excitatory inputs and vary in size
according to the magnitude of the stimulation. One graded potential is
often not enough to cause a neuron to fire
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PSYCHOLOGY AND LIFE
d) Temporal Summation involves several excitatory or inhibitory inputs from
the same source over time
e) Spatial Summation involves several excitatory or inhibitory inputs from
different sources at the same time
2. The Biochemical Basis of Action Potentials
a) An Action Potential begins when excitatory inputs are strong enough to
overcome inhibitory inputs and involves depolarization of the neuron by
sodium ions rushing into the cell
b) Resting Potential is the slightly negative voltage of a neuron in a resting
state
c) Ion Channels in neuron membranes respond to changes in excitatory and
inhibitory input. Excitatory input causes the ion channels to allow sodium
ions into the neuron, allowing the neuron to fire. Inhibitory input causes
the ion channels to keep the neuron negatively charged, preventing the
neuron from firing.
d) The action potential then travels down the axon as adjacent areas of the
axon successively depolarize
e) When the fluid inside the neuron becomes positive, the sodium ion
channels close and potassium ion channels open, allowing potassium
ions to exit the cell, restoring negative charge of the neuron.
f) Action potentials obey the All-or-None Law. The size of the action potential
is not influenced by the intensity of stimulation beyond the threshold level.
g) After firing, neurons enter a Refractory Period, a period during which they
cannot fire or will only fire with more intense stimulation dm normal
C. Synaptic Transmission
1. Transmission of neural impulses between neurons involves the movement of
neurotransmitters across the synaptic cleft
a) A Synapse is a small physical gap between neurons
b) Once an action potential reaches an axon terminal button, vesicles release
neurotransmitters into the synaptic gap chemical substances that
stimulate other neurons. The neurotransmitters then traverse across the
synaptic gap and attach to receptor molecules embedded in the
postsynaptic neuron membrane.
D. Neurotransmitters and Their Functions
1. At least 60 substances are suspected to function as neurotransmitters in the brain
2. Acetylcholine, a neurotransmitter found in both the central and peripheral nervous
systems, is implicated in memory loss associated with Alzheimer’s disease and in
some types of respiratory failure
3. Gamma-Amino Butyric Acid (GABA) is thought to be related to anxiety, as depressants
bind to receptor molecules sensitive to GABA and cause sedation
4. Catecholamines such as dopamine and norepinephrine play prominent roles in mood
disturbances and schizophrenia
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CHAPTER3: THE BIOLOGICAL BASES OF BEHAVIOR
a) Decreased levels of norepinephrine have been related to depression
b) Increased levels of dopamine have been related to schizophrenia
5. Serotonin is involved in autonomic processes, arousal, and depression
6. Endorphins are neuromodulators that modify the activities of postsynaptic neurons
and may play an important role in emotional behaviors
DISCUSSION QUESTIONS
1. A fundamental, yet often overlooked, assumption of this chapter is that Darwin’s Theory of Natural
Selection accurately explains how humans reached our current stage of development. Indeed, it has
become so well accepted that few students will stop to wonder how this chapter would be different
if it were incorrect. But what