Lecture 2
The Science of Psychology
Today’s Outline
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Critical Thinking & Science
Psychological Methods
Types of data
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Self report
Observation
Research Design
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Archival
Correlational
Longitudinal
Experimental
Methods of Psychology:
Scientific Method
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Science starts with an attitude and a desire
for the truth
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Systematic empirical study of phenomena
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__________: keep the bias out, include all data
and information even if it doesn’t “fit”
__________: based on observable events
__________: must be measurable
Short Video
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What was the study?
Did people believe it?
What’s a placebo?
Why do placebos work?
Problems with Common Sense
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People see some parts of the world and miss
others
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due to preconceptions, ability, attention, etc.)
People notice those things that fit
preconceptions
People often believe to be true whatever
feels good
The Scientific Method
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To develop theories about the world and to
test those theories using observations
Theory: An explanation
Scientific theory is backed by data
The scientific process
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Is self correcting (theories are tested, then
revised, then tested)
Theories are _________
The process is objective and public
The Science of Psychology
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Separating anecdotes, folk wisdom and advice
from data and conclusions!
Scientific Research is…
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Formulating _______________
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Testing __________ using the scientific method
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Interpreting the results
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Communicating the results --- realistically
The goals of science
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Description: What happens?
Prediction: When does it happen?
Explanation: Why does it happen?
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Theory
Causal Inferences
Intervention/Application: What could be
done to help?
These all build on each other
Self Report
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Self-report methods: ask participants to tell
you
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Interviews
Questionnaires
Daily diary methods
Observational Data
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Observational Data
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Observations in natural settings
Laboratory-based observation
Research Designs
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Archival – digging through the vaults…
Correlational research – when one goes up,
what happens to the other?
Longitudinal research – how do things relate
over time?
Experimental research – if one is changed,
what happens to the other?
Archival Research
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Researchers examine existing data that may
or may not have been intended for research
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Harker and Keltner (2001) used yearbook
pictures to predict marital outcomes 30 years
later
Archival Results
Smiling at age 20 predicted:
Correlational Research
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Assess the naturally occurring associations
among two variables
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Positive correlation
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rewards are positively associated with satisfaction
Negative correlation
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conflicts are negatively associated with satisfaction
Correlational research
The statistical concept of a “correlation coefficient
(r)”
Perfect positive
correlation (+1.00)
No relationship (0.00)
Perfect negative
correlation (-1.00)
Correlation does not imply causation!
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Three possible interpretations of any
correlation
Pros and Cons of Correlational
Research (descriptive)
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Advantages
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Disadvantages
Longitudinal Research
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Data collected at 2 or more time points
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Associations among variables across time
How are feelings of love across time
associated with divorce?
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Longitudinal Research
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Associations among variables within a day
How does a partner’s behavior during the day
influence feelings of commitment at night?
Pros and Cons of Longitudinal
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Advantages
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Disadvantages
Experimental Research
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Manipulate one variable to see if it causes
changes in another variable.
A
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B
Does arousal lead to greater liking?
Testing the WHATs and WHYs
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1:1 correspondence
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If you pour x into y, you know x caused the
explosion
If you pour x and z into y, you don’t know what
caused the explosion
Random Assignment
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In large enough samples, characteristics will be
equally distributed
Experimental:
Video Games & Violence
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What is an independent variable?
What is a dependent variable?
What is the point of experiments?
What is random assignment?
How are differences controlled?
Pros and Cons of Experimental
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Advantages
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Disadvantages