This study focuses on explaining the occurrence and development of compulsive behaviors from habit hypothesis. Investigators will study both OCD patients and healthy individuals using Hardwick's forced-response time task(2019), the habit Go/No-Go task, and the Intra-Extra Dimensional Set Shift task. Investigators aim to explore the cognitive abilities and differences between OCD patients and healthy controls in these three tasks. Control variables will include participants' levels of anxiety, depression, and stress, as well as sense of incompleteness and intolerance of uncertainty levels. By examining the differences in habit formation and expression abilities between OCD patients and healthy controls, and exploring the specific brain electroencephalographic activity processes in OCD patients, investigators hope to reveal the abnormal neural activity in habit-related circuits in OCD patients. This could provide new insights for the diagnosis and treatment of OCD.

Inclusion Criteria:

1. Aged between 18 and 50;
2. Y-BOCS score greater than or equal to 16;
3. Meet DSM-5 diagnostic criteria with no medication changes in the past two weeks;
4. Right-handed.

Exclusion Criteria:

1. Diagnosed with any DSM-5 disorder other than OCD;
2. Have a major physical illness;
3. Have strong suicidal ideation.