Chapter Two
Psychological
Science
RESEARCH GOALS
• Basic Research • Applied
• Answers fundamental
Research
questions about
behavior
• Implications for
everyday life;
– e.g., how nerves
provides solutions to
conduct impulses from
problems
the skin to the brain
– e.g., which type of
advertising campaign
will reduce alcohol
abuse
The Scientific Method
• = The set of assumptions, rules, and
procedures scientists use to conduct
research
• Empirical *
• = Systematic collection & analysis of data
• Objective *
• = Free from bias
Theory
• Most psychologists have a theoretical
perspective.
• What is a Theory?
• an integrated set of principles that explains
and predicts many, but not all, observed
relationships within a given domain of inquiry.
• Theories can be proven incorrect. This
requires *
• Variables that can be measured
• Relationships between variables that can be
tested
• Prediction of that relationship = a hypothesis
Hypothesis
• Research begins with a hypothesis
• What is a Hypothesis ?
• A specific and falsifiable prediction about
the relationship between or among two or
more variables.
• Variable *
• = Any attribute that can have different
values.
• Give some examples of variables.
Descriptive, Correlational, and
Experimental Research Designs
Approaches used to collect,
analyze and interpret data
Which to use?
Descriptive Methods
• Case Study *
• Record of one or more individual’s
experiences and behavior.
• Survey *
• Interview or questionnaire
measuring beliefs or
behaviors in a sample group.*
Samples and Populations
• Sample *
• the people chosen to participate in a
research project
• Population *
• The people the researcher wants to know
about
• Representative Sample *
• Study participants who closely match the
characteristics of the larger population.
Observation
• Naturalistic Observation *
• Research based on the observation
of everyday events(natural settings)
• Video: Observation of Toddler
• Laboratory Observation *
• Descriptive research conducted
by observation of behavior in
a controlled setting.
Correlation
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•
•
Correlation *
A relationship between variables
Correlational Research *
Measures variables and assesses
the relationship between them.
• Correlation Coefficient *
• Indicates the strength and direction of a
linear relationship. Correlation coefficient
ranges from -1 to +1.
Do a Correlational Study
• Is there a correlation between hair length and
playing violent video games?
• Survey students in your class.
• How many who consider their hair long play
violent video games more than 1 hr. per week?
• How many who consider their hair medium?
• How many who consider their hair short?
• Draw a graph with one axis for hair length,
another for # playing violent video games.
• Is there a correlation? A cause-effect relationship?
If there is a correlation, what might have caused it?
Correlation v. Causation
• Correlational Research does NOT prove a cause
– effect relationship.
• positive correlation between the # of violent TV shows
children watch and scores on a measure of aggressive
play can mean :
• 1. Violent TV leads to aggressive behavior.
• 2. Aggressive kids watch more violent TV.
• 3. Viewing violent TV and aggressive behavior interact.
• 4. A third variable (e.g., parenting style) leads both to
viewing violent TV and behaving aggressively.
• How do you prove a cause – effect relationship?
• Experimental method *
Experimental Method *
• A research design in which an
independent variable is manipulated to
provide evidence for a cause and effect
relationship between variables.
• Independent variable *
• The causing variable, manipulated by the
experimenter.
• Hypothesis states how the independent
variable will cause the dependent variable
to change.
• Dependent variable *
• the measured variable that is expected to
be influenced by the experimental
manipulation.
• How do you know the change in the
dependent variable was caused by the
independent variable?
• Compare two groups.
• Experimental Group *
• Exposed to the experimental manipulation
• Control Group *
• Not exposed to the experimental
manipulation (or exposed to a different level of
the manipulation)
• How do you know the two groups are the
same?
• Random assignment *
• Participants have an equal chance of
being in either group. They are assigned
to groups randomly.
• What if the participants in the experimental
group react differently because they
received a treatment? (or felt “helped”)
• Sometimes a placebo group is also used.
• Placebo *
• A control group which receives an inactive
treatment.
• Placebo effects
• changes caused by participant expectations
• What if the experimenter is biased?
• Double blind technique *
• both the researcher and the research
participants are blind to condition.
Exercise: Applied Research
• Watch the video Twitter *
• What was the hypothesis?
• Was this a descriptive study, a correlational
study, or an experiment?
• What was the independent variable?
• What was the dependent variable?
• Which was the experimental group?
• Which was the control group?
• What were some possible problems with the
study?
Ethics and Research
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Costs v. benefits
Minimize harm
Participants freely choose to participate
Protect privacy
Informed consent
Minimize deception
Debriefing
Deception and Debriefing ( video)
Institutional review board