Using the scientific method
Psych 231: Research
Methods in Psychology
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This week’s labs - Library Labs:
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Milner rooms 164d or 213c (for the psycINFO
lecture)
3rd floor (to meet with the GAs)
Check out Sharon’s library page (link on syllabus too)
Next week’s labs:
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Download and read the Assefi & Garry (2003) article
before labs
Lab Announcements
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Claim: People perform best with a good
night of sleep.
• To begin to answer it we’ve got to FOCUS the idea
• Break the general idea down into smaller more specific ideas
• Develop theories as to how & why
• EVALUATE the idea (e.g., the ROT test)
• TEST the idea: using research methods to test parts of the
theories (hypotheses)
Conducting Research: An example
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Claim: People perform best with a good
night of sleep.
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Focusing the idea
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What do we mean by performance?
• Academic performance?
• Physical performance?
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What do we mean by “good night sleep”?
• 8 hrs?, Uninterrupted?, 3 hours of REM?
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What is the underlying theory?
• e.g., consolidation of memories happen during REM sleep, so getting more REM
sleep should lead to better recall
Conducting Research: An example
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Claim: People perform best with a good
night of sleep.
Evaluating the idea (ROT)
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Can we replicate the research, do we get similar results?
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Answer may depend on how you choose to make your
observations (your research methods)
How do we observe performance? How do we observe good
sleep?
• Recall tests, recognition tests, “brain waves,” ,,,
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Are our predictions testable?
Conducting Research: An example
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Claim: People perform best with a good
night of sleep.
How might we go about trying to test this claim?
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What are the things (variables) of interest?
What is the hypothesized relationship between these
variables?
How should we test it?
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How do we observe the behavior?
What research design should we use?
Conducting Research: An example
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Observational approaches: How do we
observe the behaviors of interest?
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Naturalistic observation Direct
Participant observation Observation
Survey & interviews
Archival data
Systematic (contrived) observation
Observation
without
manipulation
General research approaches
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Naturalistic Observation: Observation and description
of behaviors within a natural setting
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Jane Goodall
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High external validity
Good for behaviors that don’t occur
(as well) in more controlled settings
Often a first step in the research
project
Can be difficult to do well
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Hard not to influence things (reactivity effect)
Takes a long time
Need multiple observers to agree
Dian Fossey
Observational Methods
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Participant Observation: The researcher engages in
the same behaviors as those being observed
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May allow observation of behaviors not normally accessible
to outside observation
Internal perspective from direct participation
• But could lead to loss of objectivity
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Potential for contamination by observer
Observational Methods
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Survey methods: Questionnaires and interviews that
ask people to provide information about themselves
• Widely used methodology
• Best way to collect some kinds of information:
• Descriptive, behavioral, and preferential
• e.g., demographic information, recreational
behavior, and attitudes
• Large amounts of data can be collected quickly with
relatively little cost (effort, time, etc.)
• But they’re often not as “cheap” as you may think
• Done correctly, can be a very difficult method
Observational Methods
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Archival data: Rather than making direct observations,
researcher examines existing public or private records
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If the appropriate existing records can be found, no need for
data collection
Data set may be more extensive than what you could collect
yourself
• However, you are limited to the data that exists, may be no way to
collect follow-up data
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Data may be of observations that you cannot (ethically)
collect or manipulate
• E.g., murder rates, who marries whom, etc.
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Word of caution: be aware of how and where the data
were collected
Observational Methods
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Advantages
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Complex patterns of behavior
in particular settings
Useful when little is known
about the subject of study
May learn about something
that never would have
thought of looking at
experimentally
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Disadvantages
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Causality is a problem
Threats to internal validity
because of lack of control
• Every confound is a threat
• Lots of alternative
explanations
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Directionality of the
relationship isn’t known
Sometimes the results are not
reproducible
Observation without manipulation
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Systematic (Contrived Observation): The observer
sets up the situation that is observed
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Observations of one or more specific variables made in a
precisely defined setting
Much less global than naturalistic observations
Often takes less time
However, since it isn’t a natural setting, the behavior may be
changed
Observational Methods
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Case studies
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Correlational
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Looking for a co-occurrence relationship between two
(or more) variables
Quasi-experimental
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Intensive study of a small set of individuals and their
behaviors
Experimental designs with one or more non-random
variables
Experimental
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Investigating the cause-and-effect relationship between
two (or more) variables through the manipulation of
variables
Types of research designs
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Intensive study of a single person, a very
traditional method
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Typically an interesting (and often rare) case
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Phineas Gage
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Sept 13, 1848 Explosion
propelled a railroad tamping
rod through his brain
This view has a number of disadvantages
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There may be poor generalizabilty
There are typically a number of possible
confounds and alternative explanations
Descriptive: Case Histories
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Measure two (or more) variables for each
individual to see if the variables co-occur
(suggesting that they are related)
Used for:
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Predictions
Reliability and Validity
Evaluating theories
Problems: Can’t make casual claims
Correlational Methods
We’d like to say:
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variable X --causes--> variable Y
To be able to do this:
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There must be co-variation between the two variables
The causal variable must come first
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Directionality problem
• Happy people sleep well
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Or is it that sleeping well when you’re happy?
Need to eliminate plausible alternative explanations
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Third variable problem
• Do Storks bring babies?
• A study reported a strong positive correlation between
number of babies and stork sightings
Causal claims
Theory 1: Storks deliver babies
Theory 2: Underlying third variable
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Manipulating and controlling variables in laboratory
experiments
Must have a comparison
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At least two groups (often more) that get compared
One groups serves as a control for the other group
Variables
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Independent variable - the variable that is manipulated
Dependent variable - the variable that is measured
Control variables - held constant for all participants in the
experiment
The experimental method
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Advantages
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Precise control
possible
Precise measurement
possible
Theory testing possible
Can make causal
claims
Disadvantages
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Artificial situations
may restrict
generalization to
“real world”
Complex behaviors
may be difficult to
measure
The experimental method