The Need for Psychological Science
 Critical Thinking
 thinking that does not
blindly accept
arguments and
conclusions
 examines
assumptions
 discerns hidden
values
 evaluates
evidence
The Amazing Randi-Skeptic
Critical Thinking
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Roadblocks to Critical Thinking:
The Limits of Intuition and
Common Sense
We are not passive recipients of
information, we ACTIVELY
INTERPRET and construct our
social perceptions to fit our
preconceived notions of how the
world works and operates.
– People are basically LAZY
THINKERS; willing to infer and
judge by using mental “shortcuts”
and otherwise not thinking too
much about things.
•
People make sense of their world
by fitting it to their preconceived
notions
The Need for Psychological Science
 Theory
 an explanation using
an integrated set of
principles that
organizes and predicts
observations
 Hypothesis
 a testable prediction
 often implied by a
theory
The Need for Psychological
Science
 Operational Definition
 a statement of procedures (operations)
used to define research variables
 Example intelligence may be operationally defined as
what an intelligence test measures
The Need for Psychological Science
 Replication
 repeating the essence of a research study to see
whether the basic finding generalizes to other
participants and circumstances
 usually with different participants in different situations
Description
Psychologists describe behavior
using case studies, surveys,
and naturalistic observation
Description
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?
Description
 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
Description
 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
Intuition and Common Sense
• Intuition and Common
Sense
• We are not passive recipients
of information, we ACTIVELY
INTERPRET and construct our
social perceptions to fit our
preconceived notions of how
the world works and operates.
– People are basically LAZY
THINKERS; willing to infer and
judge by using mental
“shortcuts” and otherwise not
thinking too much about
things.
– People make sense of their
world by fitting it to their
preconceived notions
Hindsight Bias
• Hindsight Bias – tendency to
believe that one would have
foreseen it after the results are
shown. “Seems like common
sense.” “The answer was right
there and look how obvious it
was.” “I knew it all along.”
– EX: Research on low selfesteem or high self-esteem
and susceptibility to flattery.
Perception that psychological
research findings merely verify
our common-sense
understanding
Hindsight Bias
– EX: Several weeks after a
political election, voters
often exaggerate their
ability to have predicted the
election outcome.
– EX: Mike’s stockbroker
has informed him of
substantial investment
losses. When Mike tells
his wife, she angrily
responds, “I could have
told you that your
investment plan would fail.”
Hindsight Bias
• False Consensus Effect – we
believe others agree with us
more than they do. We spend
most of out time with a biased
sample of people, mostly those
who share our attitudes and
habits.
– EX: David Letterman Activity
– EX: Conservatives think more
people support conservative
views than will people who are
liberals.
– EX: You mistakenly assume
that everyone around you
enjoys listening to country
music like you do.
Overconfidence Effect
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Overconfidence Effect – you are
more confident about how quickly
they can complete assignments or
how well they did on a test. A
result of the self-serving bias.
– EX: When American students
start college, only 2% say there is
a very good chance they will drop
out permanently or temporarily.
– EX: Planners often exhibit
overconfidence in estimating how
quickly and inexpensively they
can do a project.
– EX: Students are overconfident
about how quickly they can do
assignments and write papers.
Confirmation Bias
• Confirmation Bias – we
seek out or notice
evidence that will verify
our ideas more eagerly
than we seek evidence
that might refute them
– EX: Stereotypes we hold
– EX: Business managers
are more likely to follow the
successful careers of those
they once hired than to
track the achievements of
those they rejected.
Belief Perseverance
• Belief Perseverance –
tendency to cling to our
beliefs in the face of
contrary evidence.
– EX: Thomas believes that
rich people are stuck up.
His friend, Elaine,
introduces him to several
rich people who are not at
all stuck up. Thomas still
believes rich people are
stuck up.
– EX: Coaches continue to
believe that hot hands in bball exist
Illusory Correlations
• Both belief perseverance and
confirmation bias are results of
people making illusory
correlations (perceived
correlation that does not really
exist) – when we believe there
is a relationship between two
things, we are likely to notice
and recall instance that confirm
our belief
• EX: Infertile couples who
adopt become more likely to
conceive
• EX Hot hands in b-ball
• EX: “Of course it rained.
That is because I just washed
my car!”
Representative Heuristic
• Representative Heuristic judge a person, object, or
event by how similar it is to
what you imagine to be a
typical representative of a
category.
– We think that people who
exhibit certain characteristics
will exhibit other, related
characteristics. We think that
“like goes with like”
• EX: If I meet someone with a
laid back attitude and long
hair, I might assume they are
Californian, whereas someone
who is very polite but rigid may
be assumed to be English.
Heuristic Example
• EX: People who were told
that Linda majored in
philosophy and was a social
activist. Then they ranked
the probability of statements
about Linda
– Linda is a bank teller
– Linda is a bank teller and a
feminist
» 80% of people rated
the statement “Linda is
a bank teller and a
feminist” as more
likely than “Linda is a
bank teller”
» This contradicts the
fact that the probability
of x is greater than the
probability of x and y
co-occurring (when x
and y are independent
events)
Availability Heuristic
• Availability Heuristic –
people judge the
frequency of an event by
how easily it is brought to
mind.
– EX: People think jet
crashes are frequent
because instances of them
are salient, or easily
brought to mind.
– EX: Subjects guess that
more people die from guns
than asthma, cancer than
stroke, murder than floods.
Yet, in each case they
were wrong. perhaps
Anchoring and Adjustment
Heuristic
• Anchoring and Adjustment
Heuristic – make judgments
by starting with an initial
estimate and then adjust it to
yield the final answer. When
people are presented with an
answer to a question, they use
that answer as a reference
point.
– EX: Participants were shown
a number, either 10 or 65.
They were then asked to
estimate the proportion of
African nations in the UN.
People who saw a 10 gave an
average estimate of 25%.
Those who saw a 65 gave an
average estimate of 45%
Correlational Study
• Correlational Study
• -A statistical measure of
relationships that organizes a
set of facts and reveals how
accurately one behavior
predicts another.
• -e.g., more democratic
parents have children who
behave better
• -CANNOT prove causation
• -e.g., do democratic parents
produce better behaved
children?
• -e.g., do better behaved
children encourage parents to
be democratic?
Correlation Coefficient = r
• Correlation
Coefficient = r
• -Statistical calculation
that describes the
direction and strength
of the relationship
between two
variables.
Correlation Coefficient = r
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-Positive correlation means when
one goes up or down the other does
too. Two variables change in the same
direction, as x increases so does y
(max +1.00)
-Negative correlation: when one
goes up, the other goes down and visa
versa. Inverse relationship, as x
increases y decreases (min –1.00)
-Or not related! (~ 0.0)
-The higher the absolute value of r, the
stronger the relationship
-Perfect correlation r = + or – 1.00
-EX: r = +.37 (r – correlation
coefficient
+ - indicates direction of relationship
.37 – indicates strength of relationship
0.00 to 1.00)
Negative Correlation
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-Negative correlation: when one
goes up, the other goes down and
visa versa. Inverse relationship,
as x increases y decreases (min –
1.00)
-Or not related! (~ 0.0)
-The higher the absolute value of
r, the stronger the relationship
-Perfect correlation r = + or – 1.00
-EX: r = +.37 (r – correlation
coefficient
+ - indicates direction of
relationship
.37 – indicates strength of
relationship 0.00 to 1.00)
Scatterplot
• 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 between
the two variables. The
amount of scatter
suggests the strength of
the correlation (little
scatter indicates high
correlation).
Illusory Correlation
• A perceived
correlation that does
not really exist is an
illusory correlation the perception of a
relationship where
none exists
Measures of Central Tendency
• Measures of Central
Tendency
• Summarizes a set of data
by providing a
representative number.
• Mean - the arithmetic
average
• Ÿ Median - the center
score, the score that
divides a data set in two
• Ÿ Mode - the score that
occurs the most
Measures of Variability
• Measures of Variability
• Indicates the dispersion or
spread in a set of data – tell
you if the scores are very
different from one another or if
they cluster around the mean
• Range - the difference
between the highest and
lowest score in a set of data
• Ÿ
Standard deviation reflects the average distance
between every score and the
mean
Scientific Method
• Scientific Method
• Scientific method - Set
of rules and procedures
on how to study, observe,
or conduct experiments
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Steps include:
• 1. Formulate a research
question
• Generated by theories set of tentative
explanations of behavior
and mental processes.
Hypothesis
• Worded as a hypothesis assertion or prediction for
a behavior stated as a
testable proposition,
usually in the form of an
if-then statement
• can be verified or
falsified
• examine relationships
between variables –
specific factors that are
manipulated and
measured in research.
Research Methods
• 2. Select the research
method and design the
study
• Research methods
include experiments,
case studies, surveys,
naturalistic observation
• Must provide
operational definitions statement of the
specific procedures
used and the behaviors
studied (variables) in
the research
Collect the data
• 3. Collect the data direct observations,
questionnaires,
interviews,
psychological
tests, physiological
recordings, and
examination of archival
records
• 4. Analyze the data and
draw conclusions
Report the findings- Professional
Journals
• 5. Report the findings
• Report research in
professional journals
• Replication - repeating
the essence of a research
study, usually with
different participants in
different situations, to see
whether the basic finding
generalizes to other
participants and
circumstances.
Report the findings
• 5. Report the findings
• Report research in
professional journals
• Replication - repeating
the essence of a research
study, usually with
different participants in
different situations, to see
whether the basic finding
generalizes to other
participants and
circumstances.
Methods in Psychology
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Methods in Psychology
Setting - field vs. laboratory
Laboratory
provide uniform conditions for
all subjects
permits elimination of
irrelevant factors
may seem artificial
Field research
behavior observed in realworld setting
poor control over conditions
measures may be more
representative of reality
Data Collection Methods
• Data collection methods - selfreport vs. observational
• Self-report - procedures in
which people rate or describe
their own behavior or mental
state
• Questionnaires/ surveys
• rating scales on a scale from
1 to 7 rate your opinion of …
• judgments about perceptions
• on a scale from 1 to 100 how
hot is ...
Observational Methods
• Observational methods researchers directly observe
and record behavior rather
than relying on subject
descriptions
• naturalistic observation researcher records behavior as
it occurs naturally
• tests - researcher presents
stimuli or problems and
records responses
• experiments - researcher
measures whether variables
effect other variables in a
controlled laboratory
procedure.
Descriptive Study
• Descriptive Study
• Describes a set of
facts
• Cannot be used to
determine the causes
of behavior
Natural Observation
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Naturalistic Observation –
method of gathering descriptive
information, involves watching
behaviors of interest, without
interfering, as they occur in their
natural environments.
Advantage = obtain data about a
truly natural behavior rather than a
behavior that is in reaction to
contrived experimental situation
Disadvantage = if participants
realize they are being observed,
their behavior becomes unnatural;
difficult and time-consuming;
controls are lacking; difficult to
generalize the results of the
research; scientific objectivity is
lost if experimenters interact with
participants
Case Studies
• Case Studies – an
observation technique in which
one person, group, or situation
is studied in depth in the hope
of revealing universal
principles. Often combines
observations, interviews, tests,
and analyses of written
records.
• Advantage - useful in studying
rare or complex phenomena
• Disadvantage – can mislead
us: any given individual may
be atypical and lead to false
conclusions
Surveys
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Survey – questionnaires, tests, or
special interviews administered to
a large, random group of people to
ascertain their self-reported
attitudes or behaviors.
Advantage – enable researchers
to describe the characteristics of a
relatively small sample (a few
hundred people) and then
generalize that information to a
larger population, quickly collect
Disadvantage – easily biased
(tend to hang around people like
us), a small return rate means that
the sample is not representative,
wording of questions can have
major effects on the opinions
respondents express, not indepth, not answered truthfully
Tests
• Tests - measures various
traits and characteristics
in a population, such as
intelligence, aptitude, and
personality tests
• Reliable – consistency of
measurement.
• Test-retest reliability –
comparing scores on
tests taken on different
occasions.
• Valid – degree to which
test measures what it is
supposed to measure
Experimental Study
• Experimental Study
• Experiment = Carefully
controlled scientific procedure
in which a group of subjects
obtains a treatment and are
then observed carefully to
determine whether the
treatment makes a difference
in their behavior.
• Measures how variables
manipulated by the
experimenter have an effect on
other variables.
• Direct way to test a hypothesis
about a cause-effect
relationship between factors
Experimental Study
• Advantages – precise control
available in the experiment
allows them to isolate the
relationship between the
independent and dependent
variable and find out causeand-effect relationships.
• Disadvantages – experiments
are artificial and require great
control Can’t be used to
explore some research
questions because of ethical
concerns and some
manipulations of variables are
difficult or impossible.
Experimental Variables
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Experimental Variables
Variables – specific factors or
characteristics that can vary
(weight, time, distance between
people, scores on a test, number
of responses)
Independent variable
the controlled factor in an
experiment
e.g., democratic vs.
authoritarian classroom
hypothesized to cause an effect
on another variable
totally independent of anything the
subject does
administered to the experimental
group
Experimental Variables
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Dependent variable
the measurable behavior exhibited –
before and after the administration of
the independent variable
e.g., cooperative behavior among
students
behaviors or mental processes
affected by the independent variable
Subject variables – age, gender,
race, ethnicity, cultural background,
socioeconomic status, sexual
orientation, disability. Must consider
the impact of variables on the behavior
or mental processes being studied
Situation-relevant variables - test
conditions, experimenter behavior,
timing
Experimental Design
• Experimental Design
• Experimental vs. Control
– experiments must have
at least two groups of
subjects so that the
performance of one group
can be compared with the
other’s:
• Experimental group –
receives the independent
variable or the treatment
in an experiment
Control group
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Control group – does not receive the
independent variable, thus providing a
baseline for comparison to the
experimental group. (this group is
identical to the experimental group in
every way except that these subjects
do not receive independent variable)
Any difference in the dependent
variable between the control and
experimental groups is caused by the
independent variable
Levels may differ between or within
people
Within-subject experiment - different
levels of the independent variable are
applied to the same subject
Between-groups experiment - different
levels of the independent variable are
applied to different groups of subjects
Human Participants
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Selecting Human Participants for
Research
Sampling = choosing subjects for
research. The subjects chosen should
be representative of the population
(the total of all possible cases from
which a sample is selected) being
studied.
Random sample - every member of
pop. has an equal chance of being
selected for the study
Stratified sample – identified
subgroups in the population are
represented proportionately in the
sample.
Random assignment - every subject
has an equal chance of being placed
in either the experimental or control
group (even/odd, draw straws)
Randomization helps avoid false
results
Counterbalancing
• Group matching – the
nature of the experiment
demands a certain
population be used for an
experiment instead of
randomization.
• Counterbalancing –
change one variable with
another, i.e. if one group
of depressed clients
received an IV in the am
and the other group
received a placebo in the
pm, switch times
Experimenter Flaws
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Experimenter Flaws
Confounding of Variables - difficulty
separating the effects of
extraneous/random variables from
those of the independent variable, thus
confusing interpretation of the
experimental data
Extraneous/Random Variables uncontrolled factors that might have
affected the dependent variable
instead of or along with the
independent variable (difference in
subjects’ backgrounds, personalities,
health, and so on, that might confound
research results)
Experimenter Bias / Observerexpectancy Effect - researcher
affects the dependent variable by
encouraging subjects to respond in a
way that supports her hypothesis or
experimental results
BIAS
• Subject-expectancy effect subject knows design and tries
to produce expected result
• To prevent bias,
psychologists use blinding minimize expectancy by
removing knowledge about
experimental conditions
• Single-blind study - when
subjects are kept uninformed
as to the treatment they are
receiving
• Demand characteristics –
any cues in a study that
suggest to subjects the
purpose of the study or what
the researcher hopes to find
Placebo
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Double-blind study - neither the
experimenter nor the subjects know who has
received the independent variable.
Volunteer Bias – people who offer or
volunteer to participate in research studies
differ from people who do not.
Sample bias – sample is not truly
representative of the population being
studied. Everyone in the population of
interest did not have an equal chance of
being selected to participate in a study.
Use random assignment to reduce the
impact of random variables on the results
Big sample – the larger the sample, the
more likely it will represent a cross section of
the entire population
Placebo Effects – placebo is a physical or
psychological treatment that contains no
active ingredient but produces an effect on
the dependent variable because the person
receiving it believes it will.
Quasi-Experiments
• Quasi-Experiments
– Use pre-existing
groups, so not able to
randomly assign
participants.
Conducted when an
experiment with
adequate controls
would be unethical or
impossible.
Correlation Study
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Correlation Study
Organizes a set of facts and
reveals relationships among facts
e.g., more democratic parents
have children who behave better
Cannot prove causation
Do democratic parents produce
better behaved children?
Correlation Study - Descriptive
Statistics
Used to describe or summarize
sets of data to make them more
understandable
Data - a collection of numerical
measurements of research results
Statistics - mathematical
descriptions of data (i.e., mean,
medium, range)
Measures of Central Tendency
• Measures of Central
Tendency
• Summarizes a set of data
by providing a
representative number.
• Mean - the arithmetic
average
• Median - the center
score, the score that
divides a data set in two
• Mode - the score that
occurs the most
Measures of Variability
• Measures of Variability
• Indicates the dispersion or
spread in a set of data – tell
you if the scores are very
different from one another or if
they cluster around the mean
• Range - the difference
between the highest and
lowest score in a set of data
• Standard deviation - reflects
the average distance between
every score and the mean
Correlation
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Correlation Coefficient
Statistical calculation that describes
the direction and strength of the
relationship between two variables.
Correlations do not indicate causation.
Measures whether two variables
change in a related way (r)
Can be positive (max +1.00) – two
variables change in the same
direction, as x increases so does y
Negative (min -1.00) – inverse
relationship, as x increases y
decreases
Or not related! (~ 0.0)
The higher the absolute value of r, the
stronger the relationship
Perfect correlation r = + or – 1.00
Scatterplot
• 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 between the
two variables. The amount of
scatter suggests the strength
of the correlation (little scatter
indicates high correlation).
• A perceived correlation that
does not really exist is an
illusory correlation - the
perception of a relationship
where none exists.
Correlation Study Inferential Statistics
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Correlation Study - Inferential
Statistics
Gives probability that the sample is like
the world at large – draw conclusions
and make inferences about what the
data mean
Probability means how likely
something is
How likely are results like mine to
occur by chance?
Statistical inferences
significant result (statistically
significant) – indicates that the group
differences or correlation reflects the
real world rather than chance, with
high probability (e.g., > .95 )
not significant - results reflect chance
Ethical Issues in Psychological
Research
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Ethical Issues in Psychological
Research
http://www.sciam.com/0297issue/
0297forum.html
Ethical Guidelines – rules about
research, counseling, and
teaching that psychologists are
required to follow
Right to privacy
Informed consent vs. use of
deception
Participants will behave differently
if know study
Debrief participants after
experiment – explain research
process to participants
Animal rights
Ethical Issues in Psychological Research
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Ethical Issues in Psychological
Research
Ethical Guidelines – rules about
research, counseling, and teaching
that psychologists are required to
follow
Psych departments have review
panels to screen all proposals for
research - Institutional Review Board
Scientists must accurately report their
results, minimize subject discomfort,
and prevent any long-term negative
effects.
Voluntary Participation - people cannot
be coerced into participating in
research.
Right to Privacy - studies are
conducted to ensure confidentiality
Confidentiality
• Confidentiality - information will
not be made available to
anyone who is not directly
involved in the study
• Anonymity - participant will
remain anonymous throughout
the study - even to the
researchers.
• Use coded numbers instead of
individuals’ names and, if
possible, data are reported in
group form rather than
individual responses
Debriefing
• Deception - not possible to tell
whole truth about a study
• Truth would bias the subjects behave differently if know
study
• However, involves risk to
person’s self-esteem
• Debriefing - subjects should
be told about the purpose of
the research, the hypotheses
being tested, the nature of the
results or anticipated results,
and the implications of those
results for the science of
psychology immediately or
soon after participation.
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Issues of Risk
• Issues of Risk - subjects
should not be put at risk,
except in cases where there is
no other way to conduct
research and research results
offer promise to advance
knowledge
• Subjects have to sign consent
form and can withdraw any
time
• Right to Service - treatment
might have beneficial effects,
so persons in no-treatment
control group may be upset
Animal rights
• Animal rights - Animal Care
Guidelines
• Specify the proper care and
maintenance of animals,
including the adequacy of
space requirements,
maintenance of good health,
and supervision by qualified
personnel.
• Researchers are required to
make every effort to minimize
the pain and discomfort of
animal subjects and to seek
alternative methods for their
research if possible.
Comparing Research Methods
Frequently Asked Questions aout
Psychology
Why do psychologists study
animals?
Is it ethical to experiment on
animals?
Is it ethical to experiment on
people?
Frequently Asked Questions about
Psychology
• Is psychology free
of value
judgments?
Is psychology
potentially
dangerous?
Frequently Asked Questions
about Psychology
Does behavior vary with
gender?