Kool, WouterGershman, SamuelCushman, Fiery2019-10-032017-07-21Kool, Wouter, Samuel Gershman, and Fiery Cushman. 2017. Cost-Benefit Arbitration Between Multiple Reinforcement-Learning Systems. Psychological Science.0956-79761467-9280http://nrs.harvard.edu/urn-3:HUL.InstRepos:41467544Human behavior is sometimes determined by habit and other times by goal-directed planning. Modern reinforcement-learning theories formalize this distinction as a competition between a computationally cheap but inaccurate model-free system that gives rise to habits and a computationally expensive but accurate model-based system that implements planning. It is unclear, however, how people choose to allocate control between these systems. Here, we propose that arbitration occurs by comparing each system’s task-specific costs and benefits. To investigate this proposal, we conducted two experiments showing that people increase model-based control when it achieves greater accuracy than model-free control, and especially when the rewards of accurate performance are amplified. In contrast, they are insensitive to reward amplification when model-based and model-free control yield equivalent accuracy. This suggests that humans adaptively balance habitual and planned action through on-line cost-benefit analysis.en-USJournal Article2019-10-0310.1177/0956797617708288