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Experimental Research: Understanding the Causes of Behavior
The goal of experimental research design is to provide more definitive conclusions about the
causal relationships among the variables in the research hypothesis than is available from
correlational designs. In an experimental research design, the variables of interest are called
the independent variable(or variables) and the dependent variable. The independent variable in
an experiment is the causing variable that is created (manipulated) by the experimenter.
The dependent variable in an experiment is a measured variable that is expected to be influenced
by the experimental manipulation. The research hypothesis suggests that the manipulated
independent variable or variables will cause changes in the measured dependent variables. We
can diagram the research hypothesis by using an arrow that points in one direction. This
demonstrates the expected direction of causality:
Figure 2.2.3
Research Focus: Video Games and Aggression
Consider an experiment conducted by Anderson and Dill (2000). [7] The study was designed to test the hypothesis that
viewing violent video games would increase aggressive behavior. In this research, male and female undergraduates
from Iowa State University were given a chance to play with either a violent video game (Wolfenstein 3D) or a
nonviolent video game (Myst). During the experimental session, the participants played their assigned video games
for 15 minutes. Then, after the play, each participant played a competitive game with an opponent in which the
participant could deliver blasts of white noise through the earphones of the opponent. The operational definition of
the dependent variable (aggressive behavior) was the level and duration of noise delivered to the opponent. The
design of the experiment is shown in Figure 2.17 "An Experimental Research Design".
Figure 2.17An Experimental Research Design