Psychology2016

The Science of Psychology 29

specifically names the operations (steps or procedures) that the experimenter must use to
control or measure the variables in the experiment (Lilienfeld et al., 2015). An operational-
ization of aggressive behavior might be a checklist of very specific actions such as hitting,
pushing, and so on that an observer can mark off as the children do the items on the list.
If the observers were just told to look for “aggressive behavior,” the researchers would
probably get half a dozen or more different interpretations of what aggressive behavior is.
The name for the variable that is manipulated in any experiment is the independent
variable because it is independent of anything the participants do. The participants in the
study do not get to choose or vary the independent variable, and their behavior does not
affect this variable at all. In the preceding example, the independent variable would be
the presence or absence of violence in the cartoons.
The response of the participants to the manipulation of the independent variable is
a dependent relationship, so the response of the participants that is measured is known
as the dependent variable. Their behavior, if the hypothesis is correct, should depend on
whether or not they were exposed to the independent variable, and in the example, the
dependent variable would be the measure of aggressive behavior in the children. The
dependent variable is always the thing (response of subjects or result of some action) that
is measured to see just how the independent variable may have affected it.

THE GROUPS

If researchers do all of this and find that the children’s behavior

is aggressive, can they say that the aggressive behavior was caused

by the violence in the cartoon?

No, what has been described so far is not enough. The researchers may find that the
children who watch the violent cartoon are aggressive, but how would they know if their
aggressive behavior was caused by the cartoon or was just the natural aggression level of
those particular children or the result of the particular time of day they were observed?
Those sorts of confounding variables (variables that interfere with each other and their possi-
ble effects on some other variable of interest) are the kind researchers have to control for in
some way. For example, if most children in this experiment just happened to be from a fairly
aggressive family background, any effects the violent cartoon in the experiment might have

dependent variable

variable in an experiment that rep-

resents the measurable response

or behavior of the subjects in the

experiment.

independent variable

variable in an experiment that is

manipulated by the experimenter.

Watch the Video Experiments: Independent versus Dependent Variables

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