Chapter 2: Perspectives on Abnormal Behaviour

2.5 Evidence Based Practice & Empirically Supported Treatments

Cailey Strauss and Jorden A. Cummings

Section Learning Objectives

  • Describe the key components of evidence-based practice
  • Explain how a treatment is deemed empirically-supported
  • Define treatments that harm and explain why they should be of concern for mental health providers


Evidence-Based Practice

Evidence-based practice (EBP) is defined by the Canadian Psychological Association as the intentional and careful use of the best research evidence available at the time, in order to guide each clinical decision and delivered service. To practice in an evidence-based way, a clinician must make themselves aware of the best available research and utilize it while considering specific client preferences, personality traits, and cultural contexts. Selecting a treatment approach that has been shown to be effective for the specific problem is important, as well as tailoring it to fit the individual client (referred to as client specificity). Delivering treatment is therefore a more intentional process than simply learning one treatment modality and applying it indiscriminately to every client.

Given that research is constantly evolving and new studies are frequently added to the existing body of literature, evidence-based practice requires that a clinician maintain a commitment to being and staying informed. Clinicians must also not just consume empirical research, but thoughtfully evaluate it for validity. Every study has limitations, and understanding these limitations is integral to the critical consumption of research. Then, a clinician is charged with the difficult task of deciding how to translate the empirical research into every decision made in clinical practice. Lastly, there must always be open and honest communication between the clinician and client, in an environment where the client feels comfortable and safe expressing their needs.

Although EBP requires a great amount of work on the part of the service provider, it is necessary in order to protect the public from intentional or inadvertent harm. It also maximizes the chances for successful treatment. Evidence-based practice also encourages the view of Psychology as a legitimate, ethical and scientific field of study and practice.

Empirically-Supported Treatments

Born out of an increasing focus on accountability, cost effectiveness, and protecting Psychology’s reputation as a credible health service, task forces were mobilized in the 1990s to investigate the available treatments and services. By endorsing only those modalities that met certain criteria, the task forces created lists of empirically supported treatments. In order to be on the list, the therapy approach had to have been shown to be effective in controlled research settings. This means that the therapy was better than placebo in a statistically significant way, or was found to be at least as effective as an already empirically supported treatment. There was also a move towards standardized and manualized treatment. Treatments that could be easily described (and therefore taught) through a clear step-by-step set of rules were prioritized over those that could not. Clinicians were urged to utilize only those treatments that were found to be empirically supported, in an effort to be fully evidence based in practice.

The advantages of using empirically supported treatments are numerous. Subjecting each therapy to in-depth scrutiny helps to prevent ineffective or harmful approaches from being used. It therefore protects the public from adverse effects that range from paying for an ineffective treatment, to sustaining psychological damage. Focusing on empirically supported treatments serves as a quality control system for the field of Psychology, and protects it from becoming “watered down” by treatment approaches that lack efficacy. By using this system it also becomes less likely that one will make ethical missteps. When a clinician commits to evidence based practice using only empirically supported treatments, the public can be confident that they will receive therapy that is cost effective and has been shown to have a high likelihood of helping them.

However, any big change within a field is likely to have negative consequences no matter how beneficial it may be. There have been several arguments made against a system that strictly adheres to empirically supported treatments. Some took issue with the notion that “validity” is objective and can ever be achieved. They argued that validity is an ever-changing process and that judgments of validity are only as good as the studies that investigate each treatment approach (some of which are plagued with small sample sizes and subpar research conditions). Other critics suggested that many legitimate therapies do not lend themselves to manualized approaches and that strict adherence to a manual does not allow the flexibility required for client specificity. Yet another argument against the list of empirically supported treatments is that it is easily misinterpreted and used as a tool of elitism. Third-party payers may decide to fund only those approaches that are on the list and exclude all others, which is not how the list was intended to be used. Also, therapy approaches for use with certain psychological disorders (notably the personality disorders) are underrepresented on the list of empirically supported treatments, leaving a large subset of clients without appropriate services. As with most issues, the concept of empirically supported treatments is therefore likely best used as a flexible guideline rather than a rigid prescription for practice.

Treatments that Harm

In 2007 Scott Lilienfeld wrote an important article about psychological treatments that cause harm. He argued that the potential for psychology treatments to be harmful had been largely ignored. Despite an increased interest in the negative side effects of psychiatric medications, the field of psychology had been allowed to “fly under the radar.” Lilienfeld posited that this oversight carried with it serious risk to both the field of psychology and the public at large. He researched potentially harmful therapies (PHTs) and broke them down into two categories: Level I (probably harmful) and Level II (possibly harmful). It was noted that the distinction between these two categories likely requires further research, as the therapies listed under Level II may actually be moved to Level I with further information gathered.

According to Lilienfeld, there are two reasons why clinicians need to be concerned about potentially harmful therapies. First, clinicians are bound by an ethical duty to avoid harming their clients. Ignorance is not a valid defense for causing harm, no matter how unintentional. Second, investigating the sometimes negative effects of therapy can shed light on potential causes of client deterioration. Learning about situations in which clients do not get better is as important as the cases in which they do – failure presents an opportunity for growth and increased knowledge. In his article Lilienfeld describes potential harm as including several possibilities: a worsening of symptoms or emergence of new ones, increased distress about existing symptoms, unhealthy dependency on the therapist, reluctance to seek future treatment when needed, and in extreme cases physical harm. Harm can even be done to family and friends of the client, as in the case of false abuse accusations. A therapy is considered a PHT if (1) it causes harmful psychological or physical effects in clients or their relatives, (2) the harmful effects are enduring and are not simply a short-term worsening of symptoms during treatment (as in the case of some PTSD treatments), and (3) the harm has been replicated by independent study. Treatments that harm are concerning because they contribute to client attrition (i.e., clients prematurely leaving therapy), long-term deterioration (i.e., a worsening of client functioning), and a general degradation of psychology’s reputation as a discipline.

In Lilienfeld’s opinion, the topic of treatments that harm requires further investigation. His suggestions for future research include the extent to which harmful therapies are being administered, reasons for the continued popularity of harmful therapies, therapist or client variables that may increase or decrease the likelihood of harm, as well as any mediating variables. He also posits that the antidote to PHTs may include using standardized questionnaires at every session to track client outcomes.


Canadian Psychological Association (2012). Evidence-based practice of psychological treatments: A Canadian perspective. Report of the CPA Task Force on Evidence-Based Practice of Psychological Treatments.

Hunsley, J., Dobson, K. S., Johnston, C., & Mikhail, S. F. (1999). Empirically supported treatments in psychology: Implications for Canadian professional psychology. Canadian Psychologist/Psychologie Canadienne, 40(4), 289-302.

Lilienfeld, S. O. (2007). Psychological treatments that cause harm. Perspectives on Psychological Science, 2(1), 53-70.


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Abnormal Psychology by Cailey Strauss and Jorden A. Cummings is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License, except where otherwise noted.

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