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Credit assignment to state-independent task representations and its relationship with model-based decision making

2019; National Academy of Sciences; Volume: 116; Issue: 32 Linguagem: Inglês

10.1073/pnas.1821647116

1091-6490

Nitzan Shahar, Rani Moran, Tobias U. Hauser, Rogier Kievit, Daniel McNamee, Michael Moutoussis, Raymond J. Dolan, Edward T. Bullmore, Raymond J. Dolan, Ian Goodyer, Peter Fonagy, Peter B. Jones, Michael Moutoussis, Tobias U. Hauser, Sharon Neufeld, Rafael Romero-García, Michelle St Clair, Petra E. Vértes, Kirstie Whitaker, Becky Inkster, Gita Prabhu, Cinly Ooi, Umar Toseeb, Barry Widmer, Junaid Bhatti, Laura Villis, Ayesha Alrumaithi, Sarah Birt, Aislinn Bowler, Kalia Cleridou, Hina Dadabhoy, Emma Davies, Ashlyn Firkins, Sian Granville, Elizabeth Harding, Alexandra Hopkins, Daniel Isaacs, Janchai King, Danae Kokorikou, Christina Maurice, Cleo McIntosh, Jessica Memarzia, Harriet L. Mills, Ciara O’Donnell, Sara Pantaleone, Jenny Scott, Pasco Fearon, John Suckling, Anne‐Laura van Harmelen, Rogier Kievit,

Neural dynamics and brain function

Model-free learning enables an agent to make better decisions based on prior experience while representing only minimal knowledge about an environment’s structure. It is generally assumed that model-free state representations are based on outcome-relevant features of the environment. Here, we challenge this assumption by providing evidence that a putative model-free system assigns credit to task representations that are irrelevant to an outcome. We examined data from 769 individuals performing a well-described 2-step reward decision task where stimulus identity but not spatial-motor aspects of the task predicted reward. We show that participants assigned value to spatial-motor representations despite it being outcome irrelevant. Strikingly, spatial-motor value associations affected behavior across all outcome-relevant features and stages of the task, consistent with credit assignment to low-level state-independent task representations. Individual difference analyses suggested that the impact of spatial-motor value formation was attenuated for individuals who showed greater deployment of goal-directed (model-based) strategies. Our findings highlight a need for a reconsideration of how model-free representations are formed and regulated according to the structure of the environment.