title: Model-based learning protects against forming habits.
abstract: Studies in humans and rodents have suggested that behavior can at times be "goal-directed"-that is, planned, and purposeful-and at times "habitual"-that is, inflexible and automatically evoked by stimuli. This distinction is central to conceptions of pathological compulsion, as in drug abuse and obsessive-compulsive disorder. Evidence for the distinction has primarily come from outcome devaluation studies, in which the sensitivity of a previously learned behavior to motivational change is used to assay the dominance of habits versus goal-directed actions. However, little is known about how habits and goal-directed control arise. Specifically, in the present study we sought to reveal the trial-by-trial dynamics of instrumental learning that would promote, and protect against, developing habits. In two complementary experiments with independent samples, participants completed a sequential decision task that dissociated two computational-learning mechanisms, model-based and model-free. We then tested for habits by devaluing one of the rewards that had reinforced behavior. In each case, we found that individual differences in model-based learning predicted the participants' subsequent sensitivity to outcome devaluation, suggesting that an associative mechanism underlies a bias toward habit formation in healthy individuals.
authors: Department of Psychology, New York University, 6 Washington Place, New York, NY, 10003, USA, claire.gillan@gmail.com.
authors: Claire M
authors: CM
authors: Gillan
authors: A Ross
authors: AR
authors: Otto
authors: Elizabeth A
authors: EA
authors: Phelps
authors: Nathaniel D
authors: ND
authors: Daw
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D003216:Conditioning, Operant; D003657:Decision Making; D056344:Executive Function; D005260:Female; D006040:Goals; D006184:Habits; D006801:Humans; D008297:Male; D008875:Middle Aged; D008960:Models, Psychological; D011581:Psychological Tests; D012054:Reinforcement, Psychology; D055815:Young Adult