This randomized controlled trial examines the effects of a mobile-based gamified combined cognitive bias modification (CBM-C) intervention on obsessive-compulsive symptoms, obsessive beliefs, attentional and interpretation biases, depressive symptoms, and psychological distress. The gamified CBM-C condition is compared to a standard mobile-based CBM-C and a placebo control condition. All interventions are delivered via a mobile application. Assessments are conducted at baseline, post-intervention (week 4), and 3-month follow-up.
Age 18 years or older
Primary diagnosis of obsessive-compulsive disorder (OCD), confirmed by a licensed clinician using the Structured Clinical Interview for DSM-5 (SCID-5)
No current suicidal ideation or psychotic symptoms
Access to the internet and a mobile phone
Presence of active suicidal ideation or psychotic symptoms
Unstable psychiatric medication use (e.g., recent dose change within the past month or expected change during the intervention period)
Significant neurological or medical illness that may interfere with participation
Visual impairments that would prevent accurate perception of colored stimuli (e.g., color blindness)
Parallel
Gamified-Combined Cognitive Bias Modification
BehavioralA gamified version of the combined cognitive bias modification (CBM-C) intervention, which includes both attention and interpretation bias modification tasks. The attention component is a modified dot-probe task, and the interpretation component consists of OCD-related scenarios with word-completion exercises. Gamification elements such as feedback and visual rewards are embedded to enhance motivation and engagement. The presentation order of the two intervention components will be counterbalanced: half of the participants will receive the attention bias task first followed by the interpretation task; the other half will receive the interpretation task first followed by the attention bias task. The intervention is delivered via mobile phone in eight sessions over four weeks (two sessions per week).
Standard Combined Cognitive Bias Modification
BehavioralA standard version of the combined cognitive bias modification (CBM-C) intervention, consisting of attention and interpretation bias tasks without gamification features. The attention task is a modified dot-probe paradigm, and the interpretation task involves OCD-related scenarios followed by word-completion exercises. The presentation order of the two intervention components will be counterbalanced: half of the participants will receive the attention bias task first followed by the interpretation task; the other half will receive the interpretation task first followed by the attention bias task. The intervention is delivered via mobile phone in eight sessions over four weeks (two sessions per week).
Placebo
BehavioralA placebo version of the standard CBM-C intervention that retains the same structure and timing but omits all active bias modification elements. The attention task (modified dot-probe) presents probes equally behind threat and neutral stimuli, and the interpretation task includes OCD-related scenarios with word-completion items that lead to neutral outcomes. No manipulations are applied to shift cognitive bias. The presentation order of the two intervention components will be counterbalanced: half of the participants will receive the attention bias task first followed by the interpretation task; the other half will receive the interpretation task first followed by the attention bias task. The intervention is delivered via mobile phone in eight sessions over four weeks (two sessions per week).
Yale-Brown Obsessive Compulsive Scale
This clinician-administered measure is used to assess the severity of obsessive-compulsive symptoms. It includes 19 items in total; however, only the first 10 items are used to calculate the total score. Each item is rated on a 0 to 4 scale, resulting in a total score range of 0 to 40. Higher scores indicate greater symptom severity (worse outcome).The measure is conducted through a semi-structured clinical interview.
Obsessive Beliefs Questionnaire-44
This self-report measure is used to assess dysfunctional beliefs commonly associated with obsessive-compulsive symptoms. It consists of 44 items rated on a Likert-type scale ranging from 1 to 7. The total score ranges from 44 to 308. Higher scores indicate that the individual has more maladaptive obsessive-compulsive beliefs (worse outcome).
OC bias index
Measure of interpretation biases. It is a computerized task that requires participants to read and imagine themselves in 10 OC-relevant test scenarios and 10 non-OC-relevant scenarios with a title and missing letter in the final word of the sentence. Participants are then provided with a recognition rating form where they see the title of only the 10 OC-relevant scenarios in which they had previously imagined themselves. Each title corresponds with four different interpretations: target bias (OC-positive and OC-negative), and foil bias (foil-positive and foil-negative). Participants are asked to rate (on a 4-point scale) each sentence independently in terms of how similar each interpretation option is to the meaning of the scenario they had previously read. Target and Foil Bias Index scores are calculated by subtracting ratings for negative items from ratings for positive items. A positive score indicates that the individual has more OC-positive interpretations (better outcome).
Dot-Probe Task with Eye-Tracking
A computerized task measuring attention bias using 48 trials combining probe type, position, and image type (neutral vs. OCD-related). Each trial includes a fixation cross (500 ms), a picture pair (1500 ms), and a directional probe replacing one image. Participants respond via keyboard; bias scores are calculated by subtracting response times for probes replacing OCD-related vs. neutral images. More negative bias scores indicate reduced attention to OCD-related stimuli (better outcome). Eye-tracking (Gazepoint HD 150Hz) measures (a) vigilance: first fixation latency and frequency (including direction bias), (b) disengagement: first fixation duration, and (c) sustained attention: total fixation count and duration. Post-assessment reductions in early, frequent, or prolonged fixations on OCD-related stimuli compared to baseline are interpreted as improved attentional control (better outcome).
Hamilton Depression Rating Scale
This clinician-rated measure is used to assess the severity of depressive symptoms. The version used includes 17 items, each rated on a scale of 0 to 2 or 0 to 4, depending on the item. Total scores range from 0 to 52. Higher scores indicate greater severity of depressive symptoms (worse outcome). The assessment is conducted through a structured clinical interview.
Kessler Psychological Distress Scale
This self-report measure is used to assess general psychological distress based on symptoms of anxiety and depression experienced over the past 30 days. It includes 10 items rated on a 5-point scale from 1 to 5. Total scores range from 10 to 50, with higher scores indicating greater levels of distress (worse outcome).
Feedback Form Questionnaire
This self-report form is used to assess participants' perceptions and experiences regarding the intervention they received. It consists of three sections: (1) perceived benefit and impact of the intervention, (2) usability and practicality of the program, and (3) qualitative feedback on helpful and unhelpful aspects of the intervention. The first section includes 4 items rated on a 5-point scale from 0 (not at all) to 4 (very much). The second section consists of 4 items rated on a 5-point scale from 1 (strongly disagree) to 5 (strongly agree). The third section includes open-ended questions that allow participants to elaborate on which elements of the intervention were helpful or not. Additionally, the form includes a categorical question assessing participants' views on session duration and an optional space for further suggestions.
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Dokuz Eylul University
Lead sponsor
The Scientific and Technological Research Council of Turkey
Collaborator
