01 chapter 1_thinking critically with psychological science_student
TRANSCRIPT
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Goals of PsychologyDescription
Explanation
Prediction
Influence
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Hindsight Biasis the I-knew-it-all-alongphenomenon.
After learning the outcome of an event, manypeople believe they could have predicted that veryoutcome...
Hindsight Bias
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Sometimes we think we know morethan we actually know.
Overconfidence
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Critical Thinking
Critical thinking doesnot accept argumentsand conclusions blindly.
It examinesassumptions, discernshidden values,evaluates evidence andassesses conclusions.
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Scientific MethodAn approach to knowledge that relies on a
systematic method of testing theories:
1. hypotheses
2. collecting data
3. explaining the data4. revisions
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Scientific Method Theory:
Systematic explanation of a phenomenon
Explanation using a set of principles that organizes andpredicts observations
Hypothesis:
A specific, testable prediction derived from a theory
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Scientific Method
in Action
Develop
Theory DevelopHypotheses
Gather and
analyze data
Draw
Conclusions
ReviseTheory
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Scientific Method Collecting information or gathering data
There are many different ways to collect data
The choice of method depends on the question
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Descriptive Studies: Case Studies Descriptive Studies: Case Studies
Intensive description and analysis of a single individualor just a few individuals Rich description of an individual
Limitations Case exceptions
Decreased generalizability
Observer bias
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Example: Phineas Gage (1948) Railway construction
foreman
Accidental explosionblew his tamping ironthrough his frontal lobe
3 ft 7 inches long
1 - 1/4 inches indiameter (tapered)
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A technique for ascertaining the self-reportedattitudes, opinions or behaviors of peopleusually done by questioning a representative,
random sample of people.
Descriptive Studies: Survey
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Survey issues1. Wording Effect
Wording can change the results of a survey
2. Random Sampling Allows for a representative sample
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How do we sample?
Representative sample
Sample from the population that includes importantsub-groups in the same proportions as in the population
Biased sample
Sample that does not adequately reflect the largerpopulation
Survey issues
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The random sample
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Survey issues3. Desirability Bias
People dont want others to think negatively of them
Can change responses on surveys
4. Inaccurate Introspection
How many times have you done X?
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Descriptive Studies: Observation Types: naturalistic or laboratory
Naturalistic in real (natural) settings
Laboratory in a controlledsetting
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Prediction Using Correlation Correlation a statistical measure of a relationship
How related two traits, behaviors, or events are
Ranges from -1.00 to +1.00
Two things to look at
Strength of the relationship
Direction of the relationship
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Prediction Using Correlation
Correlationcoefficient
Indicates directionof relationship
(positive or negative)
Indicates strengthof relationship(0.00 to 1.00)
r = 0.37+
Correlation Coefficient is astatistical measure of the
relationship between two variables.
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Strength of a Correlation Strength of the relationship
Ignore the sign (+ or -), and just look at the number.
Large numbers mean strong relationship (+.89 or -.89).
Numbers near zero mean weak relationship (.004 = verylittle correlation).
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Direction of a Correlation Positive: as A goes up, B goes up
Negative: as A goes up, B goes down
Positive Negative
A B A B
E.g. Anger and Aggression E.g. Partying and gradesIncreases in Anger = More partying =
Increases in Aggression lower grades
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More correlation examplesAge and foot size: r= +.70
Moderately strong positive correlation
Temperature and freezingdeaths: r= -.95 Strong negative correlation
Money and happiness: r= +.05 Very weak positive correlation
Class attendance and grades: r= +.70
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Perfect positivecorrelation (+1.00)
Scatterplotsare graphs comprised of points that aregenerated by values of two variables. The slope ofthe points depicts the direction, while the amount of
scatter depicts the strength of the relationship.
Scatterplots
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No relationship (0.00)Perfect negative
correlation (-1.00)
The Scatterplot on the left shows a negative correlation,while the one on the right shows no relationship betweenthe two variables.
Scatterplots
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Limitations of CorrelationsCant show causation
Direction: did A B? Or, did B A?
CORRELATION DOES NOT MEAN CAUSATION!
Third variable problem
Relationship between 2 variables may be due to a third,unmeasured variable
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Third Variable FACT!
Higher ice cream sales are positively correlated with increaseddrowning deaths.
Should we ban ice cream???
Probably not
Ice cream sales go up in the summer/hot weather, when morepeople are likely to also swim.
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Explaining with Experiments Experimental designs manipulate variables to assess cause
and effect
Manipulate one variable, and keep all others constant tosee what happens
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Important Terms Used in Experimentation
Independent Variable (IV): variable the experimentermanipulates
Dependent Variable (DV): variable the experimentermeasures to see what changes
Confound: an extra variable that the experimenter didnot measure but that is related to the independent anddependent variables leading to false conclusions
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Experimental Method/terms Experimental group
Group exposed to the IV, or the treatment
Control group
Group and exposed to the same experimentalenvironment but is NOT exposed to the IV
Used for comparison
Random Assignment of participants to groupsensures equality between the groups
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Experimental Methods/Terms Operational definition:
Statement of the procedures used to define researchvariables
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Experimentation: Example