Conflict and Competition between Model-based and Model-free Control

Abstract

There are two learning systems behind human decision-making: the model-based (MB) system and the model-free (MF) system. While they both contribute to decision-making behaviors, it is not clear how the two systems interact to formulate a single decision, especially when they are in conflict. This present thesis defines decision conflict between the systems in two popular binary-choice tasks: Daw’s Two-step task and Kool’s Rocket Task. We used hierarchical modeling to identify conflict-related changes during decision process using the Drift-Diffusion Model (DDM). Evidence showed that the MB system compromises when there is a conflict with the MF system, whether the conflict is on the valuational level or action level. We also looked at how a key component of obsessive compulsive disorder (OCD), the cognitive self-consciousness (CSC), affects the two learning systems during decision.