180 CHAPTER 5
Alternatively, instead of a “no treatment” or wait-list control group, research-
ers may use a placebo control group, the members of which meet with a “therapist”
with the same frequency as the members of the treatment group. The “placebo ther-
apist” refrains from using any of the active treatment techniques employed in the
treatment group, but patients still receive attention and some level of support. For
a study of your grief box therapy, a placebo control group might consist of patients
who meet with therapists who listen to their concerns or complaints—without grief
boxes, social support, or any other specifi c interventions.
With either type of control group—wait-list or placebo—researchers compare
the level of symptoms in the treatment group with that in the control group before
and after the treatment (or at equivalent times, if there was no treatment). It is
possible that symptoms of members of the control group might diminish simply
with the passage of time, and thus the crucial comparison is not whether people
in the treatment group got better—but rather how much more they improved than
did the people in the control group.
Researchers have conducted such studies for over half a century. How did they
answer the question of whether therapy works? With a resounding “yes.” Ther-
apy really does make a difference (Lambert & Ogles, 2004). And, not surprisingly,
treatment shows a larger effect when a treatment group is compared to a wait-
list control group than when a treatment group is compared to a placebo group,
which highlights the benefi cial effects of common factors (Lambert & Ogles, 2004;
Roth & Fonagy, 2005). However, studies with a wait-list control only reveal that all
the myriad factors that go into treatment are more effective than no treatment at all.
This sort of research doesn’t identify which common factors or specifi c factors lead
patients to improve (Borkovec & Miranda, 1999).
But what does it really mean to say that therapy works—that people who
receive therapy are better off than those who don’t receive therapy? How much
better off are they? This is a complex question, and researchers currently frame
it in terms of clinical signifi cance, which may be either statistically meaningful or
clinically meaningful. Consider a woman with the eating disorder bulimia ner-
vosa, which typically involves compulsively eating large amounts of food (more
than just “pigging out”—such bingeing consists of eating well past the point of
normal fullness) and then vomiting to try to prevent weight gain. Suppose that,
prior to treatment, the woman was bingeing and vomiting daily, but after treat-
ment she was doing so only three times a week. This reduction may be statistically
meaningful (although her symptoms are still over the threshold of the DSM-IV-TR
criteria for the disorder). But is it clinically meaningful—does this decrease in
symptoms improve her daily functioning or other aspects of her quality of life
(Kendall, Holmbeck, & Verduin, 2004)? Such assessments of clinical signifi cance
may be based on the patients’ own perceptions, on observations of friends and
family members of the patients, or on the therapists’ judgment.Is One Type of Therapy Generally More Effective
Than Another?
With the advent of behavior therapy in the 1960s, some researchers asked whether one
type of therapy is generally more effective than another. Researchers who addressed
this question randomly assigned participants to one of two groups, which received
two different types of treatment. Participants in the therapy groups were compared to
each other at the end of treatment, and sometimes at some later point in time.
The initial results of such research were surprising: No type of therapy
appeared more effective than another, a fi nding that has been called the Dodo bird
verdict of psychotherapy (Luborsky, Singer, & Luborsky, 1975). In the book Alice’s
Adventures in Wonderland, the Dodo Bird says: “Everybody has won, and all must
have prizes.” In this fi rst generation of psychotherapy research, researchers did not
investigate what actually transpired in the therapy sessions or whether some types
of treatment were more effective for particular disorders.Initially, studies designed to test the overall
superiority of one form of psychotherapy over
another did not fi nd one type of therapy to be
more effective. This fi nding has been called the
Dodo bird verdict, in reference to the Dodo bird’s
proclamation in Alice’s Adventures in Wonderland:
“Everybody has won and all must have prizes.”
However, the Dodo bird verdict was based on
research of particular therapies available at that
time, using less rigorous research methods than
those generally used today (Beutler, 2000).
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