• Research in Social Psychology I
• Correlational Research
• Two or more variables are measured and a relationship is established
• The correlation coefficient (r) is used to evaluate correlational relationships between variables
• The correlation coefficient can range from -1 (negative correlations) through 0 to +1 (positive correlations)
• Positive correlation: When the values of two variables increase or decrease in the same direction (e.g., more alcohol consumed during pregnancy, greater the chance of birth defects)
• Negative correlation: When the value of one variable increases and the value of a second decreases (e.g., better prenatal care, fewer birth complications)
• The magnitude of r tells you about the degree of relationship between variables (higher number = stronger correlation)
• The sign of r tells you the direction (positive or negative) of a relationship between variables
• Correlational research is used in social psychology and has many advantages (e.g., finding relationships between real-world variables)
• Correlational research cannot be used to establish a causal relationship between variables because of two problems
• The directionality problem: It is often difficult to state clearly the direction in which the causal arrow runs (i.e., does variable A cause changes in B, or does variable B cause changes in A?)
• The third-variable problem: There may be another, unmeasured variable that is the actual cause for behavior
• Research in Social Psychology II
• Experimental Research
• In experimental research the researcher manipulates (i.e., changes the value) of one variable and measures related changes in a second
• The variable manipulated is the independent variable and the one measured is the dependent variable
• Extraneous variables (unmanipulated variables that could affect the outcome of an experiment) are controlled
• The simplest experiment includes one independent variable with two groups:
• The experimental group receives some treatment (e.g., a dose of alcohol before a simulated driving test)
• The control group does not receive the treatment (e.g., no alcohol before a simulated driving task)
• The basic experiment can be expanded by adding groups (levels of the independent variable). For example, include a different dose of alcohol to subjects in different experimental groups
• Experiments may also include more than one independent variable. This is a factorial experiment
• Allows you to look at the independent effect of each independent variable
• Also allows you to look at the interaction between variables
• An interaction occurs when the effect of one variable changes over levels of a second (a violent program affects aggression when a person is angered but not when the person is not angered)
• Experimental research can be used to establish causal relationships between variables
• Research in Social Psychology II
• Types of Research
• Basic research: Done primarily to test a theory (e.g., does a prediction from balance theory hold)
• Applied research: Done to investigate a real-world problem (e.g., does a defendant's race affect jury decisions)
• Laboratory research: Done in a tightly controlled laboratory environment
• Field research: Done in the subject's natural environment