Action-sequence learning, habits and automaticity in obsessive-compulsive disorder

Enhanced habit formation, greater automaticity and impaired goal/habit arbitration in obsessive-com-pulsive disorder (OCD) are key hypotheses from the goal/habit imbalance theory of compulsion which have not been directly investigated. This study tests these hypotheses using a combination of newly developed behavioral tasks. First, we trained both OCD patients and healthy controls, using a smartphone app, to perform chunked action sequences. This motor training was conducted daily for one month. Both groups displayed equivalent procedural learning and attainment of habitual perfor-mance (measured with an objective criterion of automaticity), despite greater subjective habitual tendencies in patients with OCD, self-reported via a recently developed questionnaire. Participants were subsequently tested on a re-evaluation task to assess choice between established automatic and novel goal-directed action sequences. This task showed that both groups were sensitive to re-evaluation based on monetary feedback. However, when re-evaluation was based on physical effort, OCD patients showed a pronounced preference for the previously trained habitual sequence, hypothetically due to its intrinsic value. This was particularly evident in patients with higher compulsive symptoms and habitual tendencies, who also engaged significantly more with the motor habit-training app and reported symptom relief at the end of the study. The tendency to attribute higher intrinsic value to familiar actions may be a potential mechanism leading to compulsions and an important addition to the goal/habit imbalance hypothesis in OCD. We also highlight the potential of the app-training as a habit reversal therapeutic tool.