Unit 2: Research Methods
Aim: To what extent did a scientific approach
to psychology produce more reliable
answers?
Do Now: Choose an index card
“Psychological findings” on cards:
1. Absence makes the heart grow fonder
2. Out of sight out of mind
The Need for
Psychological Science
Psychologists, like all scientists, use the
scientific method to construct theories that
organize observations and imply testable
hypotheses
This research has 3 hurdles that tend to
skew our logic…
1. Hindsight Bias
The tendency to
believe, after
learning the
outcome, that you
knew it all along.
After Evan Marshall (former
student/teacher at Sewanhaka)
was arrested for killing his
neighbor by chopping her up into
pieces and driving around with
her head in his passenger seat,
many came out and said they
knew something was wrong with
him!!!
Monday Morning
Quarterbacking!!!
Did they really?
2. Overconfidence
• We tend to think we
know more than we do.
•
•
•
•
Common anagrams:
WREAT  WATER
ETRYN  ENTRY
GRABE  BARGE
• About how many seconds do
you think it would it have taken
you to unscramble these?
OCHSA 
REBTI 
ERTOSP 
The Barnum Effect
It is the tendency for
people to accept very
general or vague
characterizations of
themselves and take
them to be accurate.
Psychologists, as scientists,
approach the world of
behavior with skepticism.
The Need for
Psychological Science
The Scientific Method
 Theory
 an explanation using an integrated set of
principles that organizes and predicts
observations
 Hypothesis
 a testable prediction
Hypothesis
• Expresses a
relationship between
two variables.
• A variable is anything
that can vary among
participants in a study.
• Participating in class
leads to better grades
than not participating.
Operational Definitions
• Explain what you mean
in your hypothesis.
• How will the variables
be measured in “real
life” terms.
• How you
operationalize the
variables will tell us if
the study is valid and
reliable.
Let’s say your hypothesis
is that chocolate causes
violent behavior.
• What do you mean by
chocolate?
• What do you mean by
violent behavior?
Experimentation
Descriptive
Case Study
 Psychologists
study one or
more individuals
in great depth in
the hope of
revealing things
true of us all.
Is language uniquely human?
Descriptive
 Survey
 technique for ascertaining the self-reported
attitudes or behaviors of people
 usually by questioning a representative, random
sample of people
 Random Sample
 a sample that fairly represents a population
because each member has an equal chance of
inclusion
Descriptive
 False Consensus Effect
 tendency to overestimate the extent to
which others share our beliefs and
behaviors
 Population
 all the cases in a group, from which
samples may be drawn for a study
Descriptive
 Naturalistic
Observation
 observing and
recording behavior
in naturally
occurring situations
without trying to
manipulate and
control the situation
Correlational
 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)
Correlational Method
Correlation
expresses a
relationship between
two variable.
Does not show
causation.
As more ice cream is eaten,
more people are murdered.
Does ice cream cause murder, or murder cause people to eat ice cream?
Correlational
 Scatterplot
 a graphed cluster of dots, each of which
represents the values of two variables
 the slope of the points suggests the direction of
the relationship
 the amount of scatter suggests the strength of
the correlation
Correlation
Perfect positive
correlation (+1.00)
No relationship (0.00)
Perfect negative
correlation (-1.00)
Scatterplots, showing patterns of correlations
Correlation
Height and Temperament of 20 Men
Height in
Subject Inches Temperament
1
2
3
4
5
6
7
8
9
10
80
63
61
79
74
69
62
75
77
60
75
66
60
90
60
42
42
60
81
39
Height in
Subject Inches Temperament
11
12
13
14
15
16
17
18
19
20
64
76
71
66
73
70
63
71
68
70
48
69
72
57
63
75
30
57
84
39
Correlation
95
Temperament 90
scores 85
80
75
70
65
60
55
50
45
40
35
30
25
55
60
65
70
Height in inches
75
80
Scatterplot of Height and Temperament
85
Correlation Coefficient
A number that
measures the
strength of a
relationship.
Range is from -1 to +1
The relationship gets
weaker the closer you
get to zero.
Which is a stronger
correlation?
-.13 or +.38
-.72 or +.59
-.91 or +.04
Illusory Correlation
 Illusory Correlation
 the perception of a relationship
where none exists
 For example…
Experimentation
 Experiment
 an investigator manipulates one or more
factors (independent variables) to
observe their effect on some behavior or
mental process (the dependent variable)
 Used to illustrate cause and effect
Experimentation
 Placebo
 an inert substance or condition that may be
administered instead of a presumed active agent,
such as a drug, to see if it triggers the effects
believed to characterize the active agent
 Double-blind Procedure
 both the research participants and the research
staff are ignorant (blind) about whether the
research participants have received the treatment
or a placebo
 commonly used in drug-evaluation studies
Experimentation
 Experimental Group
 the condition of an experiment that exposes
participants to the treatment, that is, to one
version of the independent variable
 Control Group
 the condition of an experiment that contrasts
with the experimental treatment
 serves as a comparison for evaluating the effect
of the treatment
Experimentation
 Random Assignment
 assigning participants to
experimental and control conditions
by chance
Independent Variable
Whatever is being
manipulated in the
experiment.
The variable whose
effect is being
studied.
If there is a drug in an
experiment, the
drug is almost always
the independent
variable.
Dependent Variable
The dependent variable
would be the effect
of the drug.
• Whatever is being
measured in the
experiment.
• It is dependent on the
independent variable.
• In psychology it is
usually a behavior or
mental process.
Experimentation
Confounding variable-are factors affecting
the dependent variable in an experiment.
Random variables-are uncontrollable
factors that could affect the dependent
variable in an experiment.
Experimenter bias-occurs when a
researcher encourages subjects to
respond in a way that supports their
hypothesis.
STATISICAL ANALYSIS
Statistical analyses are used to interpret
research results.
Descriptive statistics describe data.
Inferential statistics are used to draw
conclusions and make inferences about
what the data mean.
Central Tendency
 Mean, Median and Mode.
 Watch out for extreme scores or outliers.
Let’s look at the salaries of the
employees at Dunder Mifflen Paper
in Scranton:
$25,000-Pam
$25,000- Kevin
$25,000- Angela
$100,000- Andy
$100,000- Dwight
$200,000- Jim
$300,000- Michael
The median salary looks good at
$100,000.
The mean salary also looks good at
about $110,000.
But the mode salary is only $25,000.
Maybe not the best place to work.
 Range
 the difference between the highest and lowest
scores in a distribution
 Standard Deviation
 It measures the average difference between each
score and the mean of the data set or a measure
of how much scores vary around the mean
 Statistical Significance
 a statistical statement of how likely it is that an
obtained result occurred by chance
Normal Distribution
Distributions
• Outliers skew
distributions.
• If group has one high
score, the curve has a
positive skew
(contains more low
scores)
• If a group has a low
outlier, the curve has
a negative skew
(contains more high
scores)
APA Ethical Guidelines for
Research
IRB- Internal
Review Board
Both for humans and
animals.
Animal Research
Clear purpose
Treated in a humane
way
Acquire animals
legally
Least amount of
suffering possible.
Human Research
No Coercion- must
be voluntary
Informed consent
Anonymity
No significant risk
Must debrief