An Intervention to Correct Dualistic Reasoning About the Effectiveness of Psychotherapy for Biologically Caused Mental Disorders

Exemption: Perception of Mental Disorders

The goal of this clinical trial is to test in three samples, including sample 1: lay people without reported depression symptoms, sample 2: lay people with reported depression symptoms and sample 3: mental health clinicians. The main questions it aims to answer are: 1) do each of these populations show a bias against psychotherapy wherein they judge psychotherapy to be less effective, relative to baseline ratings, when a mental illness (i.e., depression) is attributed to biological factors, 2) whether an intervention emphasizing the neurobiological effects of psychotherapy can remove this bias against psychotherapy for biologically-caused mental disorders, and 3) whether this intervention is more effective compared to an active control intervention that emphasizes the effectiveness of psychotherapy, but not its neurobiological effects. Participants will

• rate the effectiveness of psychotherapy for depression before and after learning about the biological causes of depression
• be assigned to one of three conditions: 1) an intervention condition where participants will receive a brief reading passage (approximately 126 words in length) providing psychoeducation about how psychotherapy changes the brain of an individual with depression, or 2) an active control condition where participants will receive a reading passage (approximately 115 words) emphasizing the effectiveness of psychotherapy, or 3) a control condition where they will receive no additional materials
• as a secondary outcome, participants will also rate the effectiveness of medication for depression, before and after learning about the biological causes of depression

Overview: Previous studies showed that biological explanations for mental disorders, which are popularizing, cause laypeople and clinicians to judge that psychotherapy is less effective. This could be clinically detrimental, as the combination of pharmacotherapy and psychotherapy is often optimal. Objective: This study tests a "de-biasing" intervention developed to counteract the flawed dualistic belief that activities perceived as occurring in the mind (e.g., psychotherapy) do not necessarily affect the brain. Design, Setting, Participants: This survey was conducted between September 10, 2020 and April 2, 2022 through Qualtrics.com over laypeople with and without symptoms of depression, and licensed clinicians in the U.S. Participants were randomly assigned to either an intervention condition explaining how psychotherapy results in brain-level changes, an active control condition explaining the effectiveness of psychotherapy but not its biological mechanisms, or a control condition with no intervention. Main Outcome Measures: Participants rated the efficacy of psychotherapy for biologically caused depression before and after being assigned to one of the three conditions. It was hypothesized that the dualism intervention would increase ratings of the effectiveness of psychotherapy, even after participants learned about the biological causes of depression. It was also expected that this intervention would increase psychotherapy ratings more than the active control materials that also emphasized the effectiveness of psychotherapy.

Inclusion Criteria:

• Participation was open to individuals in the US
• For sample 1, lay people without reported depression symptoms, there was no specific inclusion criteria
• For sample 2, lay people with reported depression symptoms, participants were included if they indicated via Amazon Mechanical Turk Toolkit that they experienced symptoms of depression
• For sample 3, mental health clinicians, participants were included if they indicated that they were a practicing mental health clinician in the United States

Exclusion Criteria:

• For lay people without reported depression symptoms, the only exclusion criteria was age (i.e., no participants under 18 years of age)
• For lay people with reported depression symptoms, participants were excluded if they scored < 14 on the Beck Depression Inventory-II (BDI-II), indicating no depression symptoms
• For mental health clinicians, participants were excluded if they indicated that they were not currently licensed