Running title: BLOCKING IN THE SOCIAL DOMAIN Efficient learning mechanisms hold in the social domain and are implemented in the medial prefrontal cortex

When we are learning to associate novel cues with outcomes, learning is more efficient if we take advantage of previously learned associations and thereby avoid redundant learning. The blocking effect represents this sort of efficiency mechanism and refers to the phenomenon in which a novel stimulus is blocked from learning when it is associated with a fully predicted outcome. Although there is sufficient evidence that this effect manifests itself when individuals learn about their own rewards, it remains unclear whether it also does when they learn about others’ rewards. We employed behavioral and neuroimaging methods to address this question. We demonstrate that blocking does indeed occur in the social domain and it does so to a similar degree as observed in the individual domain. On the neural level, activations in the medial prefrontal cortex (mPFC) show a specific contribution to blocking and learning-related prediction errors in the social domain. These findings suggest that the efficiency principle that applies to reward learning in the individual domain also applies to that in the social domain, with the mPFC playing a central role in implementing it. DOI: https://doi.org/10.1093/scan/nsu130 Posted at the Zurich Open Repository and Archive, University of Zurich ZORA URL: https://doi.org/10.5167/uzh-100547 Accepted Version Originally published at: Seid-Fatemi, Azade; Tobler, Philippe N (2015). Efficient learning mechanisms hold in the social domain and are implemented in the medial prefrontal cortex. Social Cognitive and Affective Neuroscience, 10(5):735-743. DOI: https://doi.org/10.1093/scan/nsu130 Running title: BLOCKING IN THE SOCIAL DOMAIN Efficient learning mechanisms hold in the social domain and are implemented in the medial prefrontal cortex Azade Seid-Fatemi and Philippe N. Tobler University of Zurich Number of words: 5,958 Author Note: Azade Seid-Fatemi, Laboratory for Social and Neural Systems Research, Department of Economics, University of Zurich, Zurich, Switzerland; Philippe N. Tobler, Laboratory for Social and Neural Systems Research, Department of Economics, University of Zurich, Zurich, Switzerland. We thank several members of the Department of Economics, University of Zurich, and Bertram Gerber for fruitful discussions, JiSoo Park for assistance with data collection, and Christopher Burke, Tamara Herz, Quentin Huys, and Yosuke Morishima for helpful comments on a previous version of this paper. This work was supported by funding from the Swiss National Science Foundation (PP00P1_128574). We also acknowledge the Neuroscience Center Zurich (ZNZ) and the Zurich Center for Integrative Human