1. 1.2 Research Methods
AP Psychology

2. Methods for studying behavior…
Experimental method
Surveys
Naturalistic observation
Case study
Longitudinal method
Cross-sectional method
Correlational studies

3. Experimental Method
Carefully controlled method of investigation used to establish cause-effect relationship
The experimenter purposely manipulates and controls selected variables

5. Testable Hypothesis
Hypothesis – statement that describes the relationship between two or more variables
Must be testable, verifiable, and refutable
Null Hypothesis – no new findings / no new relationship

7. Hypothesis

8. Null Hypothesis

9. IV vs. DV
Independent Variable – factor that is manipulated or controlled by the experimenter (aka explanatory variable)
Dependent Variable – factor that is measured by the experimenter (aka response variable)
Tips…
IV influences DV
Manipulate the IV, measure the DV
Dependent on the independent
If _________ (IV) then ___________ (DV).
How the______ affects the _____.
IV DV

13. IV vs. DV Examples
An experimenter wants to determine if playing violent video games increases the frequency of aggressive behavior in children.
IV – the type of video game
DV - the amount of aggressive behavior
An experimenter wants to determine the relationship between rehearsal/repetition of a list of definitions of difficult SAT vocab words and later recall of these definitions
IV – the amount of rehearsal/repetition
DV – recall of correct definitions

15. IV vs. DV Examples
An experimenter wants to determine if a new drug reduces hyperactivity in children.
IV – drug
DV – level of hyperactivity

16. Extraneous Variables Aka – confounding / lurking / hidden
Factor that the researcher failed to control or eliminate (damage the validity)

18. Operational Definitions
Precise description of how the variable in a study will be manipulated and measured

20. Operational Definition

21. Participants in Experiments
Experimental Group – the participants who are exposed to the IV
Control Group – the participants who are exposed to all experimental conditions except the IV

25. Experimental Controls
Purpose – ensure all groups in the experiment are treated exactly the same, except the IV
Limit lurking variables!

26. Problems with Experiments
Experimenter Bias – when a researchers expectations about the outcome influence the results
Sample Bias – participants are not representative of the larger population
Aka selection bias
Volunteer Bias – differences between those willing to participate and those who don’t

28. Solutions to Problems
Random Assignment – participants are assigned to EG or CG by chance
Minimizes pre-existing differences between groups
Placebo – an inactive substance or fake treatment used as a control (
Placebo Effect
Single-Blind Study – subjects don’t know whether they are the EG or CG
Double-Blind Study – neither the researcher nor the participants know which is the EG
Eliminates experimenter bias

34. Advantages of Experiments
Identify cause-and-effect relationships
Distinguish between real and placebo effects
Can control bias (double-blind)
Manipulate the IV; measure the DV
Replication of study; increase confidence in results (IV influences DV)

35. Disadvantages of Experiments
Artificial lab vs. real life
Confounding variables could cause results
Biases (researcher or participant)
Ethical concerns when subjects are deceived
Informed consent

36. Descriptive Research
Methods that enable researchers to observe and describe behaviors without manipulating
DO NOT establish cause-and-effect