speculate that this earlier event is responsible for the fear, we cannot be cer-
tain that the fear wouldn’ t have developed without the experience. For this
reason, researchers using case studies must be cautious when speculating
about the causes of the behaviors they see.
Third, investigators ’subjective judgments can often interfere with scien-
tific objectivity in case study work. The expectancies researchers bring to a
case study may cause them to see that which confirms their hypotheses and
to overlook that which does not. It ’s possible that a different psychologist
working with the same individual might come to different conclusions. As
you will see in Chapter 3, Freud in particular has been criticized for ap-
proaching his cases with his own biases.
Strengths of the Case Study Method
With all these weaknesses, why do personality researchers occasionally usethe case study method? One reason is that other research methods might not
do the job. For example, Freud ’s concern with the deeper understanding of an
individual ’s unconscious mind is not easily examined in other ways. The rich-
ness of a single person’ s life can be lost when he or she is reduced to a few
numbers that are then added to other participants ’numbers. This was one
reason a team of researchers conducted a case study on Dodge Morgan, who
at age 54 sailed around the globe by himself (Nasby & Read, 1997). The de-
tailed analysis of Morgan ’s behavior and personality as he made his way
through this adventure provides insights unavailable through other methods.
The case study method is also valuable for generating hypotheses about the
nature of human personality. Researchers sometimes follow up case studies
with more traditional scientific investigations.
The case study method is a particularly useful research tool in at least four
situations. It is the most appropriate method when examining a rare case. Sup-
pose you wanted to investigate the personalities of political assassins. You
probably would be limited to exploring the background and behavior of only a
handful of people who fall into this category. Similarly, therapists working with
patients described as having multiple personalities often report their observa-
tions in a case study manner when recording information about what is proba-
bly a once-in-a-lifetime encounter.
The case study method is also appropriate when researchers can argue that
the individual being studied is essentially no different from all normal peopleon the dimension of interest. For example, case studies of “split-brain ”patients
have uncovered important information about the functioning of the human
brain. Participants in these studies have had the corpus callosum (which con-
nects the right and left halves of the cerebral hemisphere) severed as part of
treatment for severe epilepsy. Because the physical functions of the brain are
basically alike for all normally functioning people, studying the behavior of
these few patients tells us much about the way our right and left brains wouldoperate if not connected by the corpus callosum.
Still another appropriate use of the case study is to illustrate a treatment.
Therapists often describe in detail the procedures they used to treat a particularclient and the apparent success or failure of the therapy. A prudent therapistThe Case Study Method 29