different treatment each of the groups received, some researchers refer to the
dependent variable as the outcome variable.
However, most personality research is more elaborate than this example in-
dicates. Researchers typically use more than one independent variable. In theinformation-seeking example, an experimenter might want to further divide par-
ticipants into groups according to how shy they typically are. The researchermight predict that anxiety leads to a search for information, but only among peo-
ple who are not shy. Researchers in this hypothetical study might use two inde-
pendent variables to divide participants into groups. They might randomlyassign participants to either an anxiety (anticipates speech) or a no-anxiety
group, and within each of these groups identify those who are shy and those
who are not. If the dependent variable remains the number of questions askedof the experimenter, the results might turn out like those shown in Figure 2.2.
This figure illustrates what is called an interaction . That is, how one independent
variable affects the dependent variable depends on the other independent vari-
able. In this example, whether anxiety leads to an increase in questions depends
on whether the participant is high or low in shyness.
Manipulated Versus Nonmanipulated Independent Variables
Sometimes personality researchers randomly assign participants to conditions,
such as putting them into anxiety or no-anxiety groups. However, other times
they simply identify which group the participant already belongs to, such as
whether the person is shy or not shy. The significance of this difference is illus-
trated in the following example.
Suppose you are interested in the effect violent television programs have on
the amount of aggression people display in real life. You recruit two kinds of
participants —those who watch a lot of violent TV shows and those who watchNumber of Questions Asked
No-Anxiety
ConditionAnxiety
Condition1234 Shy ParticipantsNonshy Participants
FIGURE 2.2 An Interaction Between Two Independent Variables24 CHAPTER 2 Personality Research Methods