Behavioral Research
Chapter 9
“Conducting the Experiment”
. Conducting the Experiment
• Selecting Research Participants
– Probability vs. non probability sampling
– Sample Size
Manipulating the Independent
Variable
• Construct an operational definition of
the variable of interest .
• Set the Stage for introducing the
independent and dependent variable.
– Obtain informed consent
– Provide the rationale for why the
experiment is being conducted
– May have to use deception which carries
an obligation for a debrief at the
conclusion of the experiment.
Types of Manipulations
• Straightforward manipulations
• Staged manipulations
– Used for two reasons:
» Researcher may be trying to create some physiological
state in the participant, such as anger, or temporarily
lowering self esteem.
» May be necessary to simulate some situation that occurs
in the real world confederate Asch conformity study
Strength of the Manipulation
• Make the manipulation as strong as
possible thus maximizing the difference
between the two groups and increasing the
chance that the IV will have a statistically
significant effect on the dependent variable.
• Ethical considerations
Measuring the Dependent
Variable
• Three general types: self-report, behavioral,
physiological
• Sensitivity of the Dependent Variable
• Multiple Measures
• Cost of Measures
• Ethics.
Types of Manipulations
– Self report- can be used to measure attitudes, liking for someone,
judgments about someone’s personality characteristics intended
behaviors, emotional states, etc
– Behavioral measures: direct observation of behavior
• Rate-record the number of times the behavior occurs in a given time period
• Reaction time-how quickly a response occurs after a stimulus
• Duration-how long the behavior lasts.
– Physiological Measures -recordings of responses of the body.
• Galvanic skin response measure of general emotional arousal and anxiety by
measuring the conductance of the skin which changes when sweating occurs.
• Electromyogram measures muscle tension and is used as a measure of
tension and stress.
• Electroencephalogram-measure of electrical activity of brain cells, can be used
to record general brain arousal as a response to different activity---especially
during sleep
• Others: heart rate, blood pressure urine and blood analysis, etc.
Sensitivity of the Dependent
Variable
• Measure should be sensitive enough to
detect differences between groups
• Important when measuring human
performance
– Ceiling effects
– Floor effects
Multiple Measures
• Can strengthen the conclusions
• Independent variable (e.g. illness or stress)
may have an effect on many measurable
dependent variables.
– Missed work days
– Number of doctor visits
– Phsyiological measures
• Order effects
• may not be feasible due to cost, or ethics.
Additional Characteristics
• Demand Characteristics
• Placebo Groups
• Experimenter Expectations
Additional Considerations
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Research Proposals
Pilot studies
Manipulation Checks
Debriefing
Analyzing & Interpreting Results
• Statistical Analysis
• Communicating Research to others
– Professional meetings
– Journal articles
Method Section
• The placement of the Method section is
immediately following the Introduction. The
title is Method.
• The first sub heading is participants, left
justified and bolded. In this section you will
describe your participants as to how many,
how recruited, incentive for participation.
• The second subheading is procedure, also
left side justified, and bolded.
Procedures
• This is a subsection in which you inform
the reader of all of the details necessary
for another party to replicate your
experiment.
• First, you must obtain informed consent.
Second, you need to describe the
environment in which the experiment will
be run. This should include the set up of
the room, the number of researchers
needed and any materials.
Procedures (continued)
• You must specify the testing instrument
and scoring.
• The next subsection is Experimental
Design-again left side justified and bolded.
This is one sentence, such as the design
of the current experiment is a two session
repeated measures, post test only.
• The last section is statistical analysis
which will gone over in class.