Chapter 1 What Is Psychology? 29in drug research. Different doses of a drug (and
whether it is the active drug or a placebo) are
coded in some way, and the person administer-
ing the drug is kept in the dark about the code’s
meaning until after the experiment. To run our
cell phone study in a double-blind fashion, we
could use a simulator that automatically records
collisions and have the experimenter give instruc-
tions through an intercom so that he or she will
not know which group a participant was in until
after the results are tallied.Advantages and Limitations
of Experiments
Because experiments allow conclusions about
cause and effect, and because they permit re-
searchers to distinguish real effects from placebo
effects, they have long been the method of choice
in psychology.
However, like all methods, the experiment has
its limitations. Just as in other kinds of studies, the
participants are typically college students and may
not always be representative of the larger popula-
tion. Moreover, in an experiment, the researcher
sets up what is often a rather artificial situation,
and the participants try to do as they are told.
In their desire to cooperate, advance scientific
knowledge, or present themselves in a positive
light, they may act in ways that they ordinarily
would not.Control groups can also be crucial in descrip-
tive studies. For example, if you give a self-esteem
test only to girls, you can’t conclude that they have
lower self-esteem than boys do. And if someone
reports that divorce has long-term consequences
for the children, you will need to know how chil-
dren in a control group (whose parents are still
together) are doing.
Experimenter Effects LO 1.17
Because expectations can influence the results of
a study, participants should not know whether
they are in an experimental or a control group.
When this is so, as it usually is, the experiment is
said to be a single-blind study. But participants are
not the only ones who bring expectations to the
laboratory; so do researchers. And researchers’
expectations, biases, and hopes for a particular
result may cause them to inadvertently influence
the participants’ responses through facial expres-
sions, posture, tone of voice, or some other cue.
Such experimenter effects can be powerful; even an
experimenter’s friendly smile can affect people’s
responses in a study (Rosenthal, 1994).
One solution to this problem is to do a
double-blind study. In such a study, the person
running the experiment, the one having actual
contact with the participants, also does not know
who is in which group until the data have been
gathered. Double-blind procedures are standard
single-blind study An
experiment in which
subjects do not know
whether they are in an
experimental or a control
group.experimenter effects
Unintended changes in
subjects’ behavior as a
result of cues that the
experimenter inadver-
tently conveys.double-blind study
An experiment in which
neither the people
being studied nor the
individuals running the
study know who is in the
control group and who is
in the experimental group
until after the results are
tallied.Psychologists doing field research have studied diverse questions, such as whether men and
women differ in how much they talk and how people in crowded places modify their gaze and
body position to preserve a sense of privacy.