Reducing Biases in Clinical Judgment with Single Subject Treatment Design

Psychological literature exposes a number of biases that can influence one's judgment (e.g., pathology bias, confirmatory bias, hindsight bias, misestimation of covariance, decision heuristics, false consensus effect, and over-confidence in clinical judgment). Clinical judgment, the subjective method of arranging client data to establish a diagnosis and a treatment plan, can also be biased and may lead to inaccurate assessment and inefficient treatment. Taking repeated measures of symptoms, similar to the single subjects research design used in the behavioral sciences, may lead to better therapy because it reduces judgment bias. ********** When evaluating another person's behavior, there are numerous factors that may distort an accurate account of the response in context. Clinicians are not immune to these distortions in judgment, and several such biases will be examined in the clinical context. The use of single subject design methodology in treatment contexts may reduce these biases and help improve therapeutic endeavors. Behavior analysts recognize the benefits of the single subject research design. This ideographic approach to research, which emphasizes repeated measures of individual behavior where subjects serve as their own control under different conditions, is well suited for applied settings (Hayes, Barlow, & Nelson Gray, 1999). Clinicians using this time-series methodology can investigate not only the environmental influences on their client's therapeutic gains, but also their rate of behavioral change and its maintenance. Assessing each client's progress as an N=1 design supports the client's right to effective treatment (Van Houten et al., 1988), maintains scientific and practical standards of practice (Burns, 1990; Davison & Lazarus, 1995; Zaro, Barach, Nedelmann & Dreiblatt, 1977). Morgan & Morgan (2001), in an article in the American Psychologist, extolled the use of these designs and suggested that this technology may inform future business with managed care. There is an additional, very good reason to utilize these techniques. Specifically, it is prudent for therapists to use the single subject treatment design because this mechanical prediction technology reduces the deleterious biases involved in using clinical judgment to make a diagnosis (of category or severity) and treat a client's behavioral disorder. Many clinicians have little insight into how they make judgments in the clinical setting (Garb, 1998), and some critics argue that even when clinicians acknowledge that certain information is important, such information can have little influence on clinicians' judgments (Rock, 1994). Additionally, clinicians with many years of experience are usually not any more accurate than graduate students in clinical training (Dawes, 1989; Garb, 1998; Grove, Zald, Boyd, Snitz, & Nelson, 2000). This demonstrates that the amount of experience does not necessarily lead to better accuracy in the use of subjective methods of psychological assessment. Clinical judgment is the informal and subjective method of arranging client data to establish a diagnosis and formulate treatment plans (Grove et al., 2000). Conversely, mechanical prediction involves formal and/ or statistical techniques for the behavioral assessment of clients (Grove et al.). While therapists may contend that effective and accurate psychological assessment is the result of clinical experience, the single subject treatment design demands well-defined, specified methodological processes that are reproducible, and therefore less prone to subjective bias than clinical judgment. The Oxford English Dictionary defines bias as "An inclination; prejudice" (OED, 1989). When a person's behavior is called "biased," it implies that one response is more likely than other responses possible at that time. Bias itself is not problematic, as clinicians may be biased to use reliable data for their diagnoses, or defer diagnosis until more data is acquired. …