1. AP Psychology September 15, 2014

2. 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.

3. 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.

4. Types of Studies  They vary by purpose and methodology.  Three main types:  Experimental  Correlational  Descriptive

5. 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

6. “Conditions” in an Experiment  Experimental  exposed to independent variable  Control  not exposed to independent variable  serves as a comparison

7. 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

8. 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)

9. 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