RESEARCH METHODS
AP PsychologySeptember 15, 2014
The Scientific Method - in Psychology Starts with a THEORY
An explanation using an integrated set of principles that organizes observations and predicts behaviors or events
E.g. The root of depression is low self-esteem. Theory produces testable predictions, called
HYPOTHESES. They give direction to research. They specify what results would support or
disconnfirm the theory. E.g. People who report poorer self-image on a
particular scale would score higher on a depression scale.
The Scientific Method - in PSYCHOLOGY, cont’d. Testing can be one of three types:
DESCRIPTIVE CORRELATIONAL EXPERIMENTAL
Eventually, testing leads to a revised theory, which better organizes and predicts what we know about the topic.
Types of Studies
They vary by purpose and methodology.
Three main types: Experimental Correlational Descriptive
EXPERIMENTAL STUDIES
Only way to study cause and effect One or more factors are manipulated
in order to observe cause & effect Factor that is manipulated =
INDEPENDENT VARIABLE Factor that is being tested (or depends
on the independent variable) = DEPENDENT VARIABLE
“Conditions” in an Experiment Experimental
exposed to independent variable Control
not exposed to independent variable serves as a comparison
Variables
Which variable is which? In a study to determine the effects of
caffeine consumption on class participation
In a study to determine the effects of video game playing on aggressive behavior
In a study to determine the effect of a certain medication on anxiety symptoms
How are variables measured in an experiment? Operational definitions
Specify precisely what procedures will be used to measure and manipulate variables
E.g. “Hunger” = “hours without eating” This allows for REPLICATION (repeating
the study in a different situation)
How do researchers ensure the groups are “equal”? Random assignment
Putting subjects into experimental and control conditions by chance
Minimizes preexisting differences Allows researchers to say that results are
probably due to manipulation of the independent variable