Progressive Iterative Delivery Hypothesis: A Psychological Processing Model of Habit Formation, Obsessive-Compulsive Disorder, and Depression

Abstract

AbstractThe transformation from goal-directed behavior to habitual action is a core issue in cognitive psychology and behavioral neuroscience. The prevailing dual-system competition model divides the goal-directed system and the habit system (neurally grounded in the dorsomedial striatum (DMS) and dorsolateral striatum (DLS) respectively) as two parallel systems competing for behavioral control, yet it fails to explain why learning must be initiated by the goal-directed system, nor can it resolve the paradox of coexisting automatic rituals and repetitive rumination in obsessive-compulsive disorder (OCD).This paper proposes the Progressive Iterative Delivery Hypothesis, arguing that the two striatal subsystems form a strict unidirectional psychological processing pipeline: the upstream goal-directed system undertakes trial-and-error generation, sequencing and verification of novel behavioral sequences, while the downstream habit system receives, consolidates and automatically outputs well-calibrated modules. Habit formation is a segmented, batch-delivered and iteratively updated process along this workflow, with Hebb’s rule serving as the micro-level synaptic plasticity foundation.Within this framework, OCD is defined as workflow deadlock caused by dysfunctional termination signals of delivery, whereas depression arises from impaired upstream processing capacity and abnormally strengthened downstream consolidation driven by chronic stress. This unified model provides a mechanistic account for habit acquisition, OCD and major depressive disorder, together with testable empirical predictions.