Single Case and Idiographic Research: Introduction to the Special Issue

Full text

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Persons, J. B., & Boswell, J. F. (2019). Single case and idiographic research: Introduction to the special
issue. Behaviour Research and Therapy, 117, pp. 1-2.
Single Case and Idiographic Research: Introduction to the Special Issue
Jacqueline B. Persons
Oakland Cognitive Behavior Therapy Center and University of California, Berkeley
James F. Boswell
University at Albany, State University of New York
Our goal in organizing this special issue focused on single case and idiographic research
is to highlight the important scientific contributions that the study of the single case and the use
of idiographic methods can make to our field. Single case investigations hold an important place
in the history of behavior research and therapy, as described in the paper by Onghena et al in this
series, but have been largely supplanted by group designs. However, the pendulum appears to be
swinging back toward the study of the single case. It is unlikely to be a coincidence that the
increased interest in the single case comes at a time when the National Institutes of Health (NIH)
have called for an increased emphasis on personalized health care (Hamburg & Collins, 2010),
and strategy 3.2 of the National Institute of Mental Health’s (NIMH) Strategic Plan calls for
mental health researchers to expand and deepen the focus on personalized intervention research.
We welcome this increased focus on idiographic methods and approaches to treatment, and we
aim to support it with the collection of articles we have gathered here.
A carefully-designed single case study can test causal hypotheses about the relationship
between interventions and outcomes. The design features needed to provide this quality of
evidence are clearly described by Alan Kazdin, one of the masters of the field, in his article for
this series. Of course, replication is needed to show that the effect generalizes to other cases. But
as Kazdin (2011) points out, this is also true of large-sample randomized controlled trials
(RCTs), and as Fisher et al. (2018) point out, group-to-individual generalizability is also a threat
to our research. The Kazdin paper in this series provides a thoughtful primer of methods that can
guide readers who were not trained in single case methods, and that we hope will encourage
them to consider conducting these studies themselves and training their graduate students to do
so.
One of the other papers in the series makes methodological contributions. Onghena and
colleagues provide an introduction to changing criterion single case experimental designs, and
they describe statistical tests that can be used in this less widely used single case experimental
design (SCED). The article offers a very clear exposition that is easy for even non-
methodologically-sophisticated readers to understand. As an added bonus, the paper begins with
a gorgeous and thoughtful account of the history of single case methodology in psychology.

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A particularly beautiful and elegant feature of the single case study is that its design can
match up very closely with high-quality routine clinical practice, as Hayes (1981) showed in his
classic paper. In the present series, the paper by Caneiro, Smith, Lingon, Moseley and
O’Sullivan effectively illustrates the way that single case study design and high-quality clinical
practice can overlap. Caneiro et al. study four individuals who suffer from persistent low back
pain. The study design consists simply of intensive data collection assessing multiple variables,
including pain, pain controllability, fear, distress, sleep, and disability collected during an 8-
week baseline period, weekly during treatment, and 12 weeks later. Although clinicians may
assert that an 8-week baseline assessment period during which no treatment is provided is not
tenable, an argument can also be made that for many patients with chronic illnesses that have not
responded to many interventions, an 8-week baseline assessment that will allow the provider to
clearly identify whether the treatment provided is helpful or not, is a worthwhile investment. All
of the features of the design (long baseline, intensive data collection during the intervention,
follow up assessment) can be built into routine clinical practice, and will both increase the
quality of care and, with patient informed consent, allow clinicians to make a contribution to
knowledge. We hope that this article, and indeed all of the articles in the special series, will
encourage practitioners to consider collecting data from their patients and publishing studies that
can make a contribution to the field and to shrinking the science-practice gap.
The paper by Hayes, Hofmann, and colleagues presents a model of Process-Based
Therapy (PBT), in which interventions target processes, in contrast to the prevailing model of
treatment described in protocols that target disorders. Several of the key elements of PBT
overlap with typical elements of single case studies, such as the idiographic focus of treatment,
and the focus on mechanisms underpinning change process. PBT’s focus on process change
allows for a tighter link between research and practice, as it describes exactly the type of
thinking that the clinician carries out in the process of doing clinical work that is guided by
collecting data to develop and test hypotheses about the psychological mechanisms that maintain
and support the patient’s symptoms (Persons, 2007). We can hope the process-focused thinking
in the Hayes et al. paper, and indeed all of the articles in this special issue, will encourage
investigators who are doing larger-scaled studies, including RCTs, to collect fine-grained
process data that will allow them to learn not just about outcome, but also about the process of
change of the treatments they study.
The single case study is also an excellent medium for the development of new treatments,
as the paper by Boswell and colleagues illustrates. They flesh out the details and provide some
initial information about the feasibility and acceptability of a novel transdiagnostic strategy for
eating disorders that is based on the hypotheses that these patients’ symptoms are maintained in
part by anxiety sensitivity (beliefs about the dangers posed by somatic sensations and
experiences of anxiety), and by interoceptive deficits, including, for example, perceived
sensations of fullness that trigger beliefs that the person is fat and intense disgust emotions. The
paper examines, in 4 cases, some very creative intervention ideas that are drawn from
conceptualization and treatment of panic disorder and applied in this study to the treatment of
eating disorders, which are some of the most serious, sometimes life-threatening disorders, and
among the most refractory to change of the psychiatric disorders.

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The paper by Boettcher and Barlow also focuses on interoceptive exposure, yet for panic
and claustrophobia symptoms. Boettcher and Barlow adopt a flexible single case design to
examine the unique impact of interoceptive exposure alone, as well as combined interoceptive
and situational exposure, on panic and claustrophobia symptoms. The article raises a clinically
relevant and interesting subject (i.e., the unique and additive effects of different forms of
exposure), and the results highlight important clinical implications for adapting a treatment
component to give the most effective care to a specific patient. In a similar fashion to Boswell et
al. and Boettcher and Barlow, Sauer-Zavala et al.’s study focuses on a particular intervention
component – opposite or inconsistent action in response to urges associated with an intense
emotional state. The researchers adopted a core SCED, the alternating treatment design (ATD),
to explore the effects of an opposite action intervention in a sample of individuals with
borderline personality disorder, with clear clinical practice implications.
A hallmark of single case and idiographic research is the reliance on intensive
measurement of key variables over the course of the interventions(s), as well as the baseline
period. The paper in this series by Bentley et al. highlights this characteristic. For example,
Bentley et al. discuss the methodology and implications of real time monitoring technologies and
ecological momentary assessment for single case research. They offer a useful review of the real-
time monitoring literature and provide examples of ways to translate the data gathered from real-
time monitoring approaches to conceptualization and treatment planning.
The articles in this special issue provide encouragement and assistance to readers who
wish to incorporate intensive data collection and other features of single case design into their
research methodology and their clinical practice, so that important learning about change
processes in individual cases can contribute to clinical practice, knowledge in our field, and the
narrowing of the science-practice gap.
References
Fisher, A. J., Medaglia, J. D., & Jeronimus, B. F. (2018). Lack of group-to-individual
generalizability is a threat to human subjects research. PNAS Latest Articles, pp. 1 – 10.
Hamburg, M. A., & Collins, F. S. (2010). The path to personalized medicine. The New England
Journal of Medicine, 363(4), 301-304. doi: 10.1056/NEJMp1006304
Hayes, Steven C. (1981). Single case experimental design and empirical clinical practice.
Journal of Consulting and Clinical Psychology, 49(2), 193-211. doi:10.1037/0022-
006X.49.2.193
Kazdin, A. E. (2011). Single-case research designs: Methods for clinical and applied settings
(Second ed.). New York, NY: Oxford University Press.
Persons, J. B. (2007). Psychotherapists collect data during routine clinical work that can
contribute to knowledge about mechanisms of change in psychotherapy. Clinical
Psychology: Science and Practice, 14, 244-246.