Can listening to classical music make you
(or your child) smarter?
Elementary Psychology
Research Methods
PSY 120
Dr. Jay W. Jackson
IPFW
Does playing violent video games make
people more aggressive?
How do we answer
such questions?
Can
meditation
improve your
health?
Authority
Ways of knowing . . .
1
Common Sense, Intuition

Birds of a feather
flock together

Opposites attract

Two heads are better
than one

Too many cooks spoil
the broth

Absence makes the
heart grow stronger

Out of sight, out of
mind
Logical Analysis
All cats have four
legs. I have four
legs. Therefore, I
am a cat.
Basic Goals of Science
Science
Assumption of
determinism
 Attitude of openminded skepticism
 Method of
objective
observation


IS NOT simply an untested idea or vague
belief (consider: Theory of electricity, theory of
relativity, heliocentric theory, Atomic theory)
IS a carefully thought out set of propositions
based on sound science
Predict
Explain
Control
The Importance of Science to
Psychology
A Scientific Theory . . .

Describe


Without science, there is no psychology
Without science, psychology would be built on
unsupported opinion rather than on empirical
evidence
2
Two Basic Types of Research
Experimental
 Correlational

Experimental Research

Researcher systematically manipulates one
variable (independent variable) and then
measures another variable (dependent variable)

Observes if any change in the dependent
variable occurred as a result of the manipulation

All other variables are controlled
Experimental and Control
Groups

Experimental Group: participants who receive
some special treatment (with respect to the
independent variable)

Control Group: participants who do not receive
the special treatment
Importance of Random Assignment
Random assignment ensures that there
are no preexisting differences between
participants in the experimental group and
those in the control group
A researcher’s wife had twins. He was delighted. He
rang the minister who was also delighted. "Bring
them to church on Sunday and we'll baptize them,"
said the minister. "No," replied the researcher.
"Baptize one. We'll keep the other as a control."
H1: Anxiety Increases
Desire to Affiliate
Manipulate IV (anxiety)
Experimental group: “Shocks will be very painful”
Control group: “Shocks will be mild, painless”
Measure DV (desire to affiliate)
Observe if participant waits with others or alone
3
Participants Wanting to Wait With Others (%)
For each item, identify the independent
variable and the dependent variable
1. A biopsychologist is interested in how blood
pressure is affected by viewing a violent film
sequence as opposed to a nonviolent film
sequence.
2. A social psychologist investigates the impact
of group size on degree of conformity
expressed by participants.
Correlational Research
Advantage of experimentation
 Can establish causality

Disadvantage of experimentation
 Not all variables can be manipulated

Measure naturally occurring variables to see if a
change in one is associated with a change in
the other
Examples:
– Birth order and creativity
– Gender and math ability
– Drug use and neural functioning
– Speed limit and accidents
4
Two Properties of a Correlation
Valence (or Direction)
Correlation Coefficient ( r )

Statistic that indicates precise strength &
direction of the relationship

Ranges between -1.00 and +1.00

Sign indicates valence (direction)

Absolute value indicates strength (larger the
value, the better prediction)
Positive: increase in one variable is associated with an
increase in the other (Examples: class attendance and grade
on test, amount of exercise per week and physical health)
Negative: increase in one variable is associated with a
decrease in the other (Examples: number of alcoholic drinks
and coordination, degree of shyness and number of friends)
Zero: The variables are unrelated
Strength: Relationship is relatively strong or weak
Main advantage of correlational research
 Allows for the study of variables that can not be
examined experimentally
– Ethical limitations
– Person variables
Disadvantage of Correlational Research
 Can not establish causation
– Directional Problem
– Third Variable
Another example:
A researcher discovers
that stress and cancer are
correlated
How might you explain
the relationship?
5
A survey of over 2000 couples found that those
who lived together before getting married were
2.3 times as likely to get divorced as couples
who had not lived together
“In fact, several studies show that living
together actually leads to divorce”
http://centralillinoisproud.com/content/fulltext/?cid=3570
Fig 1.5
Evaluating Research
Headlines of Public Press Articles






Church attendance boosts immunity
Breast implants lower cancer risks but boost
suicides
Venting emotions after trauma predicts worse
outcomes
Eating fish prevents crime
Child anxiety linked to ecstasy use
Sexual lyrics prompt teens to have sex
Hypotheses . . .


Internal validity – To what extent did
the study establish causality?
 External validity – To what extent do
the findings generalize to different types
of people and settings?
 Construct validity - What does the
measure really measure? What does the
manipulation really manipulate?

Operational definitions link concepts with concrete observations
Propose how variables will be related
Must be falsifiable
– "Gold will melt in rain water”
– "Some folk remedies help with some problems”

Variables must be operationally defined
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Scientists Have Ethical
Responsibilities To:
Building Confidence in Findings

1. Replication


Science -- report findings truthfully
Participants -- prevent harm, treat with respect
Society -- to use results for good ends
2. Meta-Analysis
One thing I have learned in a
long life: that all of our
science, measured against
reality, is primitive and
childlike--and yet it is the most
precious thing we have
-- Albert Einstein
Conclusion



To pursue their scientific goals, psychologists
utilize many different research methods
Experiments are especially powerful because
they allow researchers to draw conclusions
about causality
Correlational methods are useful because they
allow for a wide range of variables to be studied
For each research scenario below, provide 3
possible explanations using causality, reverse
causality, and a third variable



Researchers measure how much violent TV a group of 100 children
watch over a 16 week period, and then measure how aggressive
these children behave toward their peers for the next 16 weeks.
They find a positive correlation.
Students in Professor Miller’s class say they want a review session.
The professor holds an open review session for two hours the day
before the exam. He writes down when each student arrives at the
session and when each departs. When the exams are graded,
professor Miller announces the results: The longer students spent at
the review session the lower their score on the exam!
A ten-year world-wide study found that as more ice cream treats
were sold near beaches, there was an increase in the number of
human fatalities by drowning.
For each scenario below, identify the experimental group, the control
group, the independent variable, and the dependent variable.
1.
Dr. Bendele wants to know if people with depression will benefit from
cognitive behavioral therapy. He recruits 90 people seeking treatment for
clinical depression. They all complete a test to measure their degree of
depression. Then, he randomly assigns each participant to one of two groups.
The first group is put on a waiting list (they receive no therapy). The second
group receives cognitive behavioral therapy twice a week for six weeks. At the
end of six weeks, all participants again complete the measure of depression.
Dr. Bendele will calculate the difference between the first measure of
depression and the second measure of depression to obtain an improvement
score for each participant.
2.
A study indicates that antioxidants found in blueberries may slow down the
process of aging. In this study, 19-month old rats (equivalent to 60-year old
humans) were fed either their standard diet or a diet supplemented by either
blueberry, strawberry, or spinach powder. After eight weeks, the rats were
given memory and motor tests. Although all supplemented rats showed
improvement, those supplemented with blueberry powder showed the most
notable improvement.
7
Identify the IV and DV for each:
1.
2.
3.
4.
5.
Developmental psychologists want to know if
playing video games increases children’s math
skills.
Physiological psychologists want to determine if
listening to soft music reduces heart rate.
Clinical psychologists want to know if anxiety can
be treated with Systematic desensitization
Personality researchers want to determine if
optimism can be influenced by regular exercise
Consumer psychologists examine the impact of
brand names on consumer evaluations.
Variations in Experimental Design

Within subjects design:
Expose a single group to
two different conditions

Factorial design:
Manipulate more than one
independent variable

Multivariate design:
Use more than one
dependent variable
8