1 thinking critically with psychological science chapter 1
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1
Thinking Critically with Psychological
Science
Chapter 1
2
Thinking Critically with Psychological Science
The Need for Psychological Science The limits of Intuition and
Common Sense
The Scientific Attitude
The Scientific Method
3
Thinking Critically …
Description The Case Study
The Survey
Naturalistic Observation
4
Thinking Critically …
Correlation Correlation and Causation Illusory Correlation Perceiving Order in Random
Events
5
Thinking Critically …
Experimentation Exploring Cause and Effect
Evaluating Therapies
Independent and Dependent Variables
6
Thinking Critically …
Statistical Reasoning Describing Data
Making Inferences
FAQs About Psychology
7
Impression of Psychology With hopes of satisfying curiosity, many
people listen to talk-radio counselors and psychics to learn about others and themselves.
Dr. Crane (radio-shrink)
http://ww
w.nbc.com
http://ww
w.photovault.com
Psychic (Ball gazing)
8
The Need for Psychological Science
Intuition & Common Sense
Many people believe that intuition and common sense are enough to bring forth
answers regarding human nature.
Intuition and common sense may aid queries, but they are not free of error.
9
Limits of Intuition
Personal interviewers may rely too much on their “gut feelings” when
meeting with job applicants.
Taxi/ G
etty Images
10
Errors of Common Sense
Try this !
Pennies in a cup
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
11
Hindsight Bias is the “I-knew-it-all-along” phenomenon.
After learning the outcome of an event, many people believe they could have
predicted that very outcome. We only knew the dot.com stocks would plummet after
they actually did plummet.
Hindsight Bias
12
OverconfidenceSometimes we think we know more than we actually know.
Anagram
BARGEGRABE
ENTRYETYRN
WATERWREATHow long do you think it would take to unscramble
these anagrams?
People said it would take about 10 seconds, yet on
average they took about 3 minutes (Goranson, 1978).
13
Psychological Science
1. How can we differentiate between uniformed opinions and examined conclusions?
2. The science of psychology helps make these examined conclusions, which leads to our understanding of how people feel, think, and act as they do!
14
4 GOALS OF PSYCHOLOGY
1. DESCRIBE
2. EXPLAIN
3. PREDICT
4. INFLUENCE
15
The Scientific Attitude
The scientific attitude is composed of curiosity (passion for exploration), skepticism
(doubting and questioning) and humility (ability to accept responsibility when wrong).
16
Critical Thinking
Critical thinking does not accept arguments and
conclusions blindly.
It examines assumptions,
discerns hidden values, evaluates
evidence and assesses
conclusions.The Amazing Randi
Courtesy of the Jam
es Randi E
ducation Foundation
17
Scientific Method
Psychologists, like all scientists, use the scientific method to construct theories that organize, summarize
and simplify observations.
18
Psychologists Analyze Data Scientifically
• Behavior must be measurable– detected by direct observation or
other measuring devices
• Methods and data must be objective
– no opinions or bias
• Scientists must be able to communicate the results of their experiment to others
– Meetings, journals
19
Guidelines cont.
• Procedures must be repeatable– Other scientists can do
the same procedure or experiment
• Must use an organized and systematic approach in gathering data
20
The Testing Method
•Reliability: a measure of consistency; must yield similar results on different testing occasions
•Validity: the degree to which a test measures what it is suppose to measure
21
A Theory is an explanation that integrates principles and organizes
and predicts behavior or events.
For example, low self-esteem contributes to depression.
Theory
22
A Hypothesis is a testable prediction, often prompted by a theory, to enable
us to accept, reject or revise the theory.
People with low self-esteem are apt to feel more depressed.
Hypothesis
23
Research would require us to administer tests of self-esteem and
depression. Individuals who score low on a self-esteem test and high on a depression test would confirm our
hypothesis.
Research Observations
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Research Process
25
Description
Case Study
A technique in which one person is studied in depth to reveal underlying behavioral principles.
Is language uniquely human?
Susan K
uklin/ Photo R
esearchers
26
Case Study
A clinical study is a form of case study in which the therapist
investigates the problems associated
with a client.
http://behavioralhealth.typepad.com
Clinical Study
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METHODS cont.• CASE-STUDY METHOD:
– Study an individual’s background forces that influence their behavior (family background, home life, neighborhood, school, etc.)
– ADVANTAGE:• Can exhibit individual differences and suggest
hypotheses• Can study phenomena you cannot manipulate• Can generate hypotheses to be tested
– DISADVANTAGE:• Information comes from family,
teachers and friends of individual being studied (biased?)
• Info. may be misleading• Can’t generalize nor replicate• Observer bias could be present• Cannot show causality• Psychologists can guide patients into saying
what they want hear
28
METHODS cont.
• INTERVIEWS:– One-on-one questioning– ADVANTAGE:
• Develop rapport, relaxed atmosphere, questions in advance/flexibility
– DISADVANTAGE:• getting rid of the personal
prejudices of the interviewer, difficulty in expressing the results of an interview in exact terms
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METHODS cont.
• QUESTIONNAIRE:– ADVANTAGES:
• Gather facts about individuals or opinions
• Answers can be treated statistically
30
METHODS cont.• TESTS
– I.Q.– Aptitude (A.S.V.A.B.)– Achievement (A.C.T., S.A.T.,
M.A.P.)– ADVANTAGES:
• more objective data than interviews and questionnaires
• Results can be expressed in statistical terms
• Scores can be compared with scores for large groups
– DISADVANTAGES:• Results do not give full and final
answers to individual problems
31
Survey
A technique for ascertaining the self-reported attitudes, opinions or behaviors of people usually done by questioning a
representative, random sample of people.
http://ww
w.lynnefeatherstone.org
32
Survey• Reveals attitudes and behaviors of large sample of people
•Learn about behavior and mental processes that cannot be observed in the natural setting or studied experimentally
33
Limitations
• Limited generalization• Replication sensitive to sample selected
• Give socially desirable answers• Exaggerated answers to foul up results
• Different interviewers for different samples (gender, SES, ethnicity)
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Limitations (cont.)
•Easy to bias by Wording Effect
-“Given the number of shootings in schools, should we regulate handguns? True or False
-Cannot establish causal relationships
35
Survey
Wording can change the results of a survey.
Q: Should cigarette ads and pornography be allowed on television? (not allowed vs.
forbid)
Wording Effect
36
Survey
A tendency to overestimate the extent to which others share
our beliefs and behaviors.
False Consensus Effect
37
Samples and Populations
• Example: Alf Landon defeated Franklin D. Roosevelt in 1936 poll (Roosevelt won by landslide)- surveyed voters by phone-during Great Depression
Wealthy->phones>Republican
38
Samples• Must accurately represent the population they are intended to reflect.
• Only representative samples allow us to generalize from research samples to populations.
39
Sample/Population• Sample: The individuals who are studied; part of a population
• Population: a complete group of organisms or events
• Infer:Draw a conclusion
40
Problems in Generalizing
• Research sample (consider gender, age, ethnicity)
• Volunteer Bias
41
Volunteer Bias
A source of bias or error in research that
reflects the prospect that people who offer to participate in research
studies differ systematically from people who don’t.
42
Volunteer Bias
• More willing to disclose intimate information
• Volunteers have more spare time than nonvolunteers
• How do they differ from the population at large?
43
Problems with Generalization
• Demographic variables:-age-education-socioeconomic status-marital status-number of children-location
44
Survey
Random Sampling
If each member of a population has an equal chance of inclusion into a sample, it is called a
random sample (unbiased). If the survey
sample is biased, its results are not valid.
The fastest way to know about the marble color ratio is to blindly transfer a few into a smaller jar and count them.
45
QuestionIf scientists conducted research with a “random sample” of students from Valencia, would their sample represent the
general U.S. population? Why or why not?
46
Naturalistic ObservationObserving and recording the behavior of animals in the wild and recording self-seating patterns in a multiracial school lunch room constitute naturalistic observation.
Courtesy of G
ilda Morelli
47
METHODS
• NATURAL OBSERVATION:
– Observing and recording the behavior of organisms in their natural environment.
– ADVANTAGE:
description of the way organisms behave in their surroundings
– DISADVANTAGE:
no information on how or why the behavior occurs
48
METHODS cont.
• DIRECTED OBSERVATION:– Involves observing
behavior under controlled conditions in an experimental or a laboratory setting
– ADVANTAGE:• Allows for control of
events and behaviors
– DISADVANTAGE:• Taking an organism from
its natural environment may change its behavior
49
Descriptive Methods
Case studies, surveys, and naturalistic observation describe
behaviors.
Summary
50
Assignment
• Form a hypothesis about human behavior and use the method of naturalistic observation to support/refute your hypothesis.
• Write what you observed and concluded.• Ex: If there are sales, then more women
than men will shop at malls. • Due MONDAY SEPTEMEBER 15
51
longitudinal studies
• A psychologist studies the same group of people at regular intervals over a period of years to determine whether their behavior and/or feelings have changed and if so, how.
• Ex: Studying you when you were 5, then 10, then 15, then 20, then 25, then 30, etc…
52
cross-sectional studies.
• In this study, psychologists organize individuals into groups based on age.
• Then, these groups are randomly sampled, and the members of each group are surveyed, tested, or observed simultaneously.
• Single point in time (snapshot)
• Ex: IQ, memory, disease
53
Correlation
When one trait or behavior accompanies another, we say the two correlate.
Correlation coefficient
Indicates directionof relationship
(positive or negative)
Indicates strengthof relationship(0.00 to 1.00)
r = 0.37+
Correlation Coefficient is a statistical measure of the relationship between two
variables.
54
Correlational Method
Examines the extent to which two or more variables are related and can
predict one another.
55
Correlational Method
• Virtues:-reveals relations of variables outside the lab-replication possible
• Limitations:-cannot establish causal relationships because you do not manipulate the variables
56
Correlation Coefficient
•A number that varies between +1.00 and -1.00
•Expresses the strength and direction (+/-) of the relationship between two variables
•The closer it is to 1.00 (regardless of +/-) the stronger the relationship
57
Positive Correlation
•A relationship between variables in which one variable increases as the other also increases
• Example: Hours of study and GPA
58
Positive Correlation
•A positive relationship means:As (A) increases, so does (B)
Hours of study (A) is positively correlated with GPA (B)
59
Negative Correlation
A relationship between two variables in which one
variable increases as the other decreases.
•Example: Hours of TV and GPA
60
Negative Correlation
•A negative relationship means:As (A) increases, (B) decreases
Number of hours of TV (A) has a negative relationship with GPA (B)
61
Correlation Research
• Correlational research may suggest but does not show cause and effect
• Often seems clear cut:Increase in Hours of study-> increase in
GPA • But could go other way:Students doing well in school are motivated to study more
GPA-> Hours of study
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63
64
65
Correlation Research
•Or some third factor (Confounding Variable): Achievement Motivation could cause both
-> Hours of study-> GPATest: length of marriage is correlated with male baldness.
Does marriage cause baldness?
66
Perfect positivecorrelation (+1.00)
Scatterplot is a graph comprised of points that are generated by values of two
variables. The slope of the points depicts the direction, while the amount of scatter depicts the strength of the relationship.
Scatterplots
67
No relationship (0.00)Perfect negativecorrelation (-1.00)
The Scatterplot on the left shows a negative correlation, while the one on the right shows no
relationship between the two variables.
Scatterplots
68
69
DataData showing height and temperament in people.
70
Scatterplot
The Scatterplot below shows the relationship between height and temperament in people. There
is a moderate positive correlation of +0.63.
71
or
Correlation and Causation
72
Illusory Correlation
The perception of a relationship where no relationship actually exists. Parents conceive
children after adoption.
Confirming evidence
Disconfirming evidence
Do not
adopt
Disconfirming evidence
Confirming evidence
Adopt
Do not conceiveConceive
Michael N
ewm
an Jr./ Photo Edit
73
IMPORTANT
Correlation
does NOT mean Causation!!!
74
Given random data, we look for order and meaningful patterns.
Order in Random Events
Your chances of being dealt either of these hands is precisely the same: 1 in 2,598,960.
75
Order in Random Events
Given large numbers of random outcomes, a few are likely to express order.
Angelo and Maria Gallina won two California lottery games on the same day.
Jerry Telfer/ S
an Francisco C
hronicle
76
Experimentation
Like other sciences, experimentation is the backbone of psychology research.
Experiments isolate causes and their effects.
Exploring Cause and Effect
77
Experimental Method
A scientific method that seeks to confirm cause and effect relationships
by introducing independent variables and observing their effects on dependent variables.
78
Experimental Method
•Treatment: in experiments, a condition received by participants so that its effects may be observed.
79
Many factors influence our behavior. Experiments (1) manipulate factors that interest us, while other factors are kept
under (2) control.
Effects generated by manipulated factors isolate cause and effect relationships.
Exploring Cause & Effect
80
An Independent Variable is a factor manipulated by the experimenter.
The effect of the independent variable is the focus of the study. For example, when examining the effects of
breast feeding upon intelligence, breast feeding is the independent variable.
Independent Variable
81
A Dependent Variable is a factor that may change in response to an
independent variable. In psychology, it is usually a behavior
or a mental process.
For example, in our study on the effect of breast feeding upon intelligence, intelligence is the dependent variable.
Dependent Variable
82
Experimental Research
Manipulate the Independent Variable (IV)
Holding all other variables constant
Observe the impact on the Dependent Variable (DV)
83
DRY MIX
Dependent Manipulate
Result Independent
Y X
Operational Definition of DV-the parameters of how we measure things
84
Experimental Research
Example: Aggression & Alcohol
(IV): Alcohol-administered at different levels, doses
(DV):Aggressive behavior
85
Experimental Research• Experimental Participants:Partake of the treatment (example: members would ingest alcohol)
• Control Group: do not take the treatment
(example: do not ingest alcohol)
*** all other conditions are held constant (helps determine cause and effect)
86
Placebo
“Sugar pill” often results in the behavior that people expect.
•Physicians now and then give sugar pills to demanding, but healthy people. They often report they feel better.
87
PlaceboExample: Tonic water & alcohol•Giving participants placebo (tonic water) but they think they are drinking alcohol
•We can conclude that changes in behavior stem from their beliefs about alcohol, not the alcohol itself.
88
Blinds and Double Blinds
Expectations:-Aggression may not have resulted from alcohol because individuals may have expectations of the effects of alcohol.
-People act in stereotypical ways when they believe they have been drinking alcohol.
(people may become less anxious in social situations, more aggressive, or more sexually aroused)
89
BlindWell-designed experiments control for the effects
of expectations by creating conditions under which participants are
unaware of the treatment.
90
Double-Blind Studies
A study in which neither the participants nor the persons measuring results know who has received the
treatment.
91
In evaluating drug therapies, patients and experimenter’s assistants should
remain unaware of which patients had the real treatment and which patients had the
placebo treatment.
Evaluating Therapies
Double-blind Procedure
92
Assigning participants to experimental (Breast-fed) and control (formula-fed) conditions by random assignment minimizes pre-existing
differences between the two groups.
* Different from random sampling
Evaluating Therapies
Random Assignment
93
ExperimentationA summary of steps during experimentation.
94
ComparisonBelow is a comparison of different
research methods.
95
Statistical Reasoning
Statistical procedures analyze and interpret data allowing us to see what the unaided eye misses.
Composition of ethnicity in urban locales
96
Describing DataA meaningful description of data is
important in research. Misrepresentation may lead to incorrect conclusions.
97
Measures of Central Tendency
Mode: The most frequently occurring score in a distribution.
Mean: The arithmetic average of scores in a distribution obtained by adding the scores and then dividing by the number of scores that were added together.
Median: The middle score in a rank-ordered distribution.
98
M&Ms Activity
1) Quantify (count) the data within the bag=total M&Ms
2) Sort them according to color (10 orange, 3 red, 4 green, etc…)
99
M&M Activity
3) Determine the groups quantity (total)
4) Find the groups mean5) Find individual mode6) Find group’s mode
Bi-modal=> two categories with the same mode
100
Measures of Central Tendency
A Skewed Distribution
101
Measures of Variation
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.
102
M&M Activity
7) Find the range of group’s bag quantity
*Highest # of m&ms-lowest # of m&ms
8) Find the range of colors in individual bag
9) Calculate Standard Deviation
103
Standard Deviation
1) Determine the mean2) Subtract the mean from every number to get
the list of deviations (negative numbers are ok)3) Square the resulting list of numbers4) Add up all the resulting squares to get their
total sum5) Divide your result by one less than the number
of items in the list6) To get the SD, take the square root of the
resulting number
104
Practice Standard Deviation
your list of numbers: 1, 3, 4, 6, 9, 19
1) mean: (1+3+4+6+9+19) / 6 = 42 / 6 = 7
2) list of deviations: -6, -4, -3, -1, 2, 12
3) squares of deviations: 36, 16, 9, 1, 4, 144
4) sum of deviations: 36+16+9+1+4+144 = 210
5) divided by one less than the number of items in the list: 210 / 5 = 42
6) square root of this number: square root (42) = about 6.48
105
Standard Deviation
106
Making Inferences
A statistical statement of how frequently an obtained result occurred by
experimental manipulation or by chance.
107
Making Inferences
Representative samples are better than biased samples.
Less variable observations are more reliable than more variable ones.
More cases are better than fewer cases.
When is an Observed Difference Reliable?
108
Making Inferences
When sample averages are reliable and the difference between them is relatively large,
we say the difference has statistical significance.
For psychologists this difference is measured through alpha level set at 5 percent (.05)
When is a Difference Significant?
109
FAQ
Q1. Can laboratory experiments illuminate everyday life?
Ans: Artificial laboratory conditions are created to study behavior in simplistic terms. The goal is
to find underlying principles that govern behavior.
110
FAQ
Q2. Does behavior depend on one’s culture?
Ans: Even when specific attitudes and behaviors vary across cultures, as they often do, the underlying processes are much the same.
Am
i Vitale/ G
etty Images
111
FAQ
Q3. Does behavior vary with gender?
Ans: Yes. Biology determines our sex, and culture further bends the genders.
However, in many ways woman and man are similarly human.
112
FAQ
Q4. Why do psychologists study animals?
Ans: Studying animals gives us the understanding of many behaviors that may have
common biology across animals and humans.
D. Shapiro, © Wildlife Conservation Society
113
FAQ
Q5. Is it ethical to experiment on animals?
Ans: Yes. To gain insights to devastating and fatal diseases. All researchers who deal with animal research are required to follow
ethical guidelines in caring for these animals.
114
FAQ
Q6. Is it ethical to experiment on people?
Ans: Yes. Experiments that do not involve any kind of physical or psychological harm beyond normal levels encountered in daily
life may be carried out.
115
FAQ
Q7. Is psychology free of value judgments?
Ans: No. Psychology emerges from people who subscribe to a set of values and judgments.
© Roger Shepard
116
FAQ
Q8. Is psychology potentially dangerous?
Ans: It can be, but it is not. The purpose of psychology is to help humanity with
problems such as war, hunger, prejudice, crime, family dysfunction, etc.
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