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© Robert J. Atkins, Ph.D.1
Thinking Critically with Psychology
© Robert J. Atkins, Ph.D.
© Robert J. Atkins, Ph.D.
What is a theory?
An explanation that organizes facts to predict
E.g. Self image and depression Black holes in space
© Robert J. Atkins, Ph.D.
What is an hypothesis?
A testable prediction Generally based on a theory
© Robert J. Atkins, Ph.D.5
What do you study? - Variables
Variables Independent variable Dependent variable
© Robert J. Atkins, Ph.D.6
How are variables related? - Correlation Positive and negative
© Robert J. Atkins, Ph.D.7
What is a positive correlation?
Mortality rates increase as people age Grades increase as study time increase
Grades
Study time
© Robert J. Atkins, Ph.D.8
What is no (zero) Correlation?
Height
Grades
© Robert J. Atkins, Ph.D.9
What is negative correlation?
As income increases free time decreases As one goes up, the other goes down
Grades
Party time
© Robert J. Atkins, Ph.D.10
What is an illusory correlation?
Adoption and conception
© Robert J. Atkins, Ph.D.11
Do not confuse correlation with causation “Correlation is not causation” Large brains (or ice cream) & violence
© Robert J. Atkins, Ph.D.
Do you remember?
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What is a theory? What is an hypothesis? What types of variables are there? What types of correlation are there? If they are correlated, did one thing cause
the other?
© Robert J. Atkins, Ph.D.13
How do you get people to study?
Population– All NSCC students
Representative Sample Random sample
– Ensures a representative sample
Random assignment– Ensures groups are equal
© Robert J. Atkins, Ph.D.14
Random sampling
Simple random Sample– Drawing names from a hat
– Lottery
Systematic random sample– Every 10th. Name
© Robert J. Atkins, Ph.D.
Do you remember?
What is a population? What is the difference between random
sample and random assignment? What is the difference between a simple
random sample and a systematic random sample?
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© Robert J. Atkins, Ph.D.16
What research methods does psychology use? Survey Case study
– In depth study of one person• E.g. Stroke victim
Naturalistic Observation– Observing behavior in a singles bar
Experimentation
© Robert J. Atkins, Ph.D.17
The experiment
Groups– Experimental group– Control group
Problems– Placebo effect
• Placebo = Pill with no drug• The double blind procedure
– Neither experimenter nor subject knows which pill is the drug or placebo.
– Hawthorne effect• Subjects give the results they think the experimenter wants
© Robert J. Atkins, Ph.D.
Do you remember?
What research methods so psychologists use? What is the difference between a case study
and naturalistic observation? What problems are there with an experiment? What is a double blind study?
– What problem does it attempt to solve?
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© Robert J. Atkins, Ph.D.
What is replication?
Repeating a study Helps to confirm the results of an earlier
study E.g. Classroom learning vs. distance
learning– Cold fusion
© Robert J. Atkins, Ph.D.
What are some problems with thinking? Seeing order in random events
– E.g. 10 heads in a row of coin toss Generalizing (Problems)
– Generalizing from unrepresentative samples– Generalizing from select cases
• Most remedial reading students in Mrs. Brown’s class are boys• Therefore, boys have more trouble reading than girls
Hindsight bias– Explaining events in hindsight
• Lee Harvey Oswald & Pres. Kennedy
© Robert J. Atkins, Ph.D.21
Do you remember?
Why do psychologists want to replicate a study?
What are some problems with thinking? After you know the results of a study, they
appear obvious. What is this called?
© Robert J. Atkins, Ph.D.
