Chapter 2: Research Methods
Psychology: From Inquiry to Understanding 1/e
C. Brown Unit 2
Scott O. Lilienfeld
Steven Jay Lynn
Laura Namy
Nancy J. Woolf
Class Notes
• Remember taking notes is like sending a text
message to yourself.
• Do not expect to write down every word.
• The members of each study group should help
th i “t
their
“team mates”
t ” fill in
i the
th gaps.
• You learn best by having to fill in the missing
information after the class period is over, but
before the day is over.
• __________________________________
• __________________________________
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The Importance of
Research Methods
• Protecting ourselves from inaccurate
impressions:
• The _____________________ Saga
Psychosurgery: A Sad History
• Following WWII thousands of returning veterans
sought assistance ____________________.
Some veterans may have been suffering from
post-traumatic stress disorder.
• Prior to the development of ________________
a lobotomy was “thought” to be a reasonable
treatment.
• Lobotomies were most prevalent in the
____________ States: nearly ________ WWII
veterans received lobotomies.
Psychosurgery
• The first controlled lobotomy was
performed by the Portuguese physician
António Moniz in 1936.
• Moniz won the Nobel Prize for medicine in
1949 for this work.
• The procedure was brought to the United
States by Drs. Walter Freeman and James
W. Watts.
Notable Cases: Rosemary
Kennedy
Rosemary Kennedy, sister of
______________________, was
given a lobotomy at age 23 to
“control” her moodiness and
growing interest in men. She was
reduced
d
d tto an iinfantile
f til mentality.
t lit
The nature of Rosemary's condition
was concealed for years by her
father, and was presented to the
public as the result of mental
retardation. Her sister, Eunice
Kennedy Shriver, founded the
___________________ in her
honor in 1968.
1
Notable Cases: Howard Dully
• Howard Dully received a
lobotomy at 12, to control his
"youthful defiance".
• He had no memory of the
procedure, and did not
discover the story of his
l b t
lobotomy
until
til h
he was iin hi
his
50’s.
• He noted, "I've always felt
different -- wondered if
something's missing from my
soul”.
• He is shown holding an icepick like instrument similar to
the one used for his lobotomy.
The Psychosurgery Saga
• Illustrates the _______________________ in
the absence of ethical guidelines, and research
methods.
• Lobotomies were adopted for use on human
j
following
g the report
p of only
y one case
subjects
study conducted on one chimpanzee.
• No controlled experiments were ever conducted.
• _________________: surgeons perceived
“improvements” in the behavior of their patients
that supported their belief in the benefits to be
derived from the procedure, and downplayed
outcomes that didn’t.
Modern Ethical
Guidelines
• HUMAN RESEARCH
– Institutional Review Board (IRB)
– ___________________
– Justification of ____________
– _______________ of subjects afterward
• Animal Research
– Institutional Animal Care and Use Committee
(IACUC)
– About 8% of psychological research uses animals
Psychosurgery Today
• In 1977, the U.S. Congress created a National
Committee for the Protection of Human Subjects
of Biomedical and Behavioral Research to
investigate allegations that lobotomy techniques
produced unethical after effects.
• It concluded that psychosurgery could have
positive effects in some cases.
• Today about 10-15 lobotomies are conducted in
the US each year.
Textbook Assignment Ch2-1
• The figure to the left is
from our textbook.
• What phenomenon is
being depicted here?
• Ans:____________
Ans:
• Were the results
supporting this procedure
more scientific than those
supporting prefrontal
lobotomies? Ans:______
• Email your response to
your SI.
The Need for Unbiased
Observations
• It is clear that behavioral scientists need to
develop rigorous methods to insure that
their conclusions are derived from ______
and __________ scientific observations,
observations
and are not “contaminated” by errors in
human judgment.
• The following exercise illustrates how
psychologists conduct experiments.
Copyright © Allyn & Bacon 2008
2
The Research Process
In Class Experiment
• In Chapter 3 we will learn that the two
sides of the brain are not symmetrical
regarding their function. This finding is
called _______________.
• In the following exercise we will “test” the
idea that the two sides of the human face
are unequal regarding the expression of
human emotion.
• Research scientists would test this
idea by posing two alternative
hypothesizes. Studies are designed
to collect data to determine if the Null
Hypothesis
yp
is statistically
y unlikely.
y
• Hypothesis: the two side of the face
differ in their capacity to express (or
conceal) emotion.
• Null Hypothesis: the two sides are
equally expressive.
Research Designs
• In this experiment a computer has been used to
split the human face into two images.
• One image is composed of the left-side and a
mirror image of the left half of the face.
• The second image is composed of the right-side
and the mirror image of the right half of the face.
Class Results
• The results from our class suggest that the
two sides of the human face are equally
expressive.
– T/F
• Vote for the most expressive side!
Class Results
• The results from our class “rejected” the
null hypothesis (the two side are equally
expressive).
Confounding Variable
• A variable__________________________
– T/F
3
Our Class Experiment
Has A Confound In Its Design
• Results from a large sample of students suggest
that the left-side of the face is emotionally most
expressive. This side of the face is controlled by
the right brain.
possibility
y that the right
g
• The confound is the p
brain is also more sensitive to the detection of
emotion, and it receives images from the left
visual field.
• Thus, we are uncertain if the left side of the face
is more expressive emotionally, or if images in
the left visual field are perceived as being more
emotionally expressive.
Answer
•
•
•
•
•
•
•
•
__________________________________
__________________________________
__________________________________
__________________________________
__________________________________
__________________________________
__________________________________
__________________________________
How to Influence +/- Thoughts
• Give the exam on a computer and present
“bogus” feedback during an exam via
computerized testing.
• Deceive the subjects into thinking they
are performing very well or very poorly.
– E.g. “Correct! Not many students select the
right answer the first time they are tested on
this concept.”
How could you change the location
of the pictures in the slides to
correct for this potential confound?
• Confer with the members of your study
group to propose a solution to the
confound.
• You have 60 seconds to meet.
• There are at least two ways to resolve the
confound.
Anatomy of an Experiment
• Some students score well on exams while
others score poorly.
• Differences between exam scores may not
always be due to the student’s
student s ability level.
level
• Positive and negative thoughts that arise
during the exam may reduce or heighten
anxiety, and differences in anxiety may
alter test performance.
Hypothetical Experiment
• In the hypothetical experiment that follows
the investigator attempts to “improve”
performance during the exam by giving
“positive”
positive feedback to the students
students. After
a response is submitted, the student is
always told that they were correct.
• A control group_____________________
4
Question
Population of Students
Random
Sample A
Random
Sample B
Experimental Group Independent
Variable
(positive feedback)
Outcome
(test scores)
Dependent
Variable
Control Group
(no feedback)
Outcome
(test scores)
Answer
•
•
•
•
•
•
•
•
__________________________________
__________________________________
__________________________________
__________________________________
__________________________________
__________________________________
__________________________________
__________________________________
Research Designs
Experiments
• Experimental Group
– ___________________________________________
___________________________________________
• Control Group
– ___________________________________________
___________________________________________
• It would be easier for the investigator to
assign all the female students to the
Experimental Group, and all the male
students to the Control Group.
Group Would this
be a good idea? Justify your answer.
• Confer with the members of your study
group and develop your response.
• You have 60 seconds to meet.
Research Designs
Experiments
• Independent Variable
– __________________________________
__________________________________
– The proposed cause of change in the
dependent variable.
• Dependent Variable
– __________________________________
__________________________________
– Proposed to be affected by the
independent variable.
Experimentation
• Random Assignment
–assigning participants
_____________________________
_____________________________
–minimizes _____________________
between those assigned to the
different groups
5
Data Analysis
Question
• The Dependent variable is the variable
that is being altered, changed or
manipulated by the investigator.
– T/F
 Researchers rely on statistics to
analyze the results they collect.
 Statistics is a branch of
mathematics that is used for
analyzing research data.
Central Tendency
Summary Statistics
• Measures of _____________________
– Mean – Mode – Median -
________________ score
________________ score
________________ score
• Measures of Variability
– Range
– Average Deviation
– Standard Deviation
Subject
1
2
3
4
5
6
7
8
9
10
11
Sum
• Mode
– the most ________________ score in a
distribution
• Mean
– the arithmetic ___________ of a distribution
– obtained by adding the scores and then dividing
by the number of scores
• Median
– the ___________ score in a distribution
– half the scores are _____ it and half are _____ it
Dispersion
Summary Statistics
Score
100
96
126
130
104
110
98
100
108
100
102
1174
Central Tendency
• Range
Mean = 1174/11 = 106.7
Mode = 100
Median = 102
– _______________________________________
_______________________________________
• Standard Deviation
– _______________________________________
_______________________________________
96 98 100 100 100
102
104 108 110 126 130
6
Subject
Class Notes
Summary Statistics
1
2
3
4
5
6
7
8
9
10
11
Sum
Mean
Score
/X – M/
/X – M/2
6.7
10.7
19.3
23.3
27
2.7
3.3
8.7
6.7
1.3
6.7
4.7
96.1
8.7
44.89
114.49
372.49
542.89
7 29
7.29
10.89
75.69
44.89
1.69
44.89
22.09
1282.19
116.56+
100
96
126
130
104
110
98
100
108
100
102
1174
106.7
• The average deviation is an intuitively sensible
way to characterize dispersion around the mean.
• The values generated by the average and
standard deviation are different numbers, but
they tend to be similar to each other.
• The average deviation is of no value in statistical
tests, and it is rarely ever calculated.
• Standard deviations are a very useful value to
calculate.
Historical Figure
Summary Statistics
• Sir Francis Galton, 1812-1911
(Charles Darwin’s half cousin).
 Measures of Variability
• Founder of ____________.
• Discovered that psychological
traits were _________
distributed.
• Proposed that a distribution be
described by only two
numbers: the ______ and
________________.
• Invented the concept of
___________ and the formula
for its computation.
 Range 96 – 130
 Average Deviation Σ/X – M/
N
Standard Deviation
Σ/X – M/2
N
Distributions
Statistical Reasoning**
• Skewed Distributions
• The Normal Curve
• Rectangular
A Skewed Distribution
15 20 25 30 35 40 45 50
90
475
710
70
Mode Median
One Family
Mean
Income per family in thousands of dollars
7
Measures of Variation**
Standard Deviation Units and the Normal
Distribution**
Range: The difference between the highest and lowest scores in a distribution.
Standard Deviation: A computed measure of how much scores vary around the mean.
h
d th
Revised 2006 PSB
Rectangular Distribution
Question
• Which value is the mode in a rectangular
distribution?
– A. Every value within the range of scores in
the distribution has the same frequency
frequency…they
they
are all the mode.
– B. The median value.
Low
Scores
High
Standard Deviation Units and the Normal
Distribution**
34% of the scores fall between the mean and 1 SD
below or above the mean
Class Notes
• For the purpose of this class round
34.13% to 34%.
• Round 13.59% to 14%.
• SD = Standard Deviation
• __________________________________
• __________________________________
• __________________________________
8
Standard Deviation Units and the Normal
Distribution**
Question
• What is the approximate percentage of
scores that fall between the mean and 1
SD above the mean?
14% of the scores fall between 1 and 2 SD either
above or below the mean
Question
• What is the approximate percentage of
scores that fall between 1 SD below the
mean and 2 SD below the mean?
Question
• For his first two college assignments Sam
earned a score of 26 in his psychology
class and a 32 in biology. In which of
these classes did Sam perform best
relative to his classmates?
– 1. Psychology
– 2. Biology
– 3. I need to know the mean and SD for the
scores in each class to answer this question.
Question
• Given: Psy: M = 20, SD = 3
Bio: M = 30, SD = 4
In terms of percentile ranks, which
score is better,
better a value of 26 in
psychology or a grade of 32 in
biology?
1. Psychology
2. Biology
Class Notes
• M = mean
• You are expected to know how to evaluate
scores using percentile rankings. Ask
questions now if this is unclear!
• __________________________________
• __________________________________
• __________________________________
• __________________________________
9
Correlation**
Correlation
• Sometimes ___________ cannot be
conducted.
• The correlation coefficient is a measure of
how strongly two variables are
“____________”.
• A high association ___________ imply
causation.
• Correlation Coefficient
– a statistical measure of the extent to which two factors vary
together, and thus how well either factor predicts the other
Indicates direction
of relationship
(positive or negative)
Correlation
coefficient
r = +.37
Indicates strength
of relationship
(0.00 to 1.00)
Examples of a Scatterplot
Correlation
• Scatterplot
– a ___________________, each of which
p
the values of _____ variables
represents
– the ______ of the points suggests the direction
of the relationship
– the _________ of scatter suggests the _______
of the correlation
• little scatter indicates ____ correlation
– also called a scattergram or scatter diagram
Copyright © Allyn & Bacon 2008
Correlation**
Perfect positive
correlation (+1.00)
No relationship (0.00)
Correlation
Perfect negative
correlation (-1.00)
Scatterplots, showing patterns of correlations
• A correlation is an x y plot of how strongly
two variables are associated.
• In a positive correlation (positive slope) as
x values ________ yy-values
x-values
values also tend to
_________.
• In a negative correlation (negative slope)
as x-values __________, y-values tend to
_________.
10
Textbook Assignment Ch2-2
Free Transportation
• In addition to experiments and studies using
correlation, two other methods are sometimes
used in psychological research. What are they?
• _______________designs involve watching
g
behavior in real-world settings.
• _______________ designs can provide
existence proofs, but are largely anecdotal.
• Of the two designs noted above,
________________has high external validity,
but low internal validity.
• Email your response to your SI.
• At the University of South Alabama a free
public transportation system (Jag Tran)
was launched just prior to the onset of the
rise in the cost of gasoline.
• It took a while for students to begin to ride
the Jag Tran.
• The association between the number of
students riding the Jag Tran and the cost
of gasoline is shown in the next slide.
Correlation and Causation
Correlation and Causation
Jag Tran and the Cost of Gas
• Is it fair to argue that the increase in the
number of Jag Tran riders has caused the
increase in the cost of gasoline?
• A strong correlation or association does
not prove ___________!!
700
Riders per We
eek
600
500
400
300
200
100
0
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
Dollars per Gallon
The Advantage of Experiments
• Experiments permit researchers to
establish cause and effect relationships
between dependent and independent
variables.
• Other types of research design may
provide greater ________ validity.
Question
• All psychological research is conducted in
laboratory settings.
– T/F
11
THE RULES
Cooperative Group Challenge
•
•
•
•
•
•
Q1
1. _____- harm resulting from the mere
expectation of harm
Placebo effect
Nocebo effect
Double blind design
Experimenter expectancy effect
Demand characteristics
Hawthorne effect
Q2
2. _____- neither researchers nor subjects
know who is in the experimental or
control group
Q3
3. _____- phenomenon in which
participants’ knowledge that they’re being
studied can affect their behavior
1.
2.
3.
4.
5.
6.
Q4
•
4. _____- improvement resulting from the
subject’s expectation of improvement
12
Q5
•
5. _____- cues that participants pick up
from a study that allow them to generate
guesses regarding the researcher’s
hypothesis
Q6
•
6. _____- improvement resulting from the
investigator’s expectation of
improvement
13