Psychiatric disorders characterized by compulsivity, such as obsessive-compulsive disorder (OCD), result in considerable functional impairment and many individuals do not respond to gold-standard treatments. Compulsivity has long been thought to occur due to exaggerated habits and reduced goal-directed control, although more recently, this conceptualization of compulsivity as an imbalance of two cognitive systems has been challenged as overly narrow. This study will recruit 100 individuals (50 adults diagnosed with OCD, 50 healthy controls) and leverage the measurement precision offered by theory-driven computational modeling in combination with electroencephalogram (EEG) to go beyond this binary theory of compulsivity, revealing how more complex interactions of neurocognitive subcomponents contribute to compulsivity-information that could ultimately lead to improved treatment personalization and clinical outcomes.