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Multi-task reinforcement learning in humans

Nature Human Behaviour volume 5, pages 764–773 (2021)Cite this article

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Abstract

The ability to transfer knowledge across tasks and generalize to novel ones is an important hallmark of human intelligence. Yet not much is known about human multitask reinforcement learning. We study participants’ behaviour in a two-step decision-making task with multiple features and changing reward functions. We compare their behaviour with two algorithms for multitask reinforcement learning, one that maps previous policies and encountered features to new reward functions and one that approximates value functions across tasks, as well as to standard model-based and model-free algorithms. Across three exploratory experiments and a large preregistered confirmatory experiment, our results provide evidence that participants who are able to learn the task use a strategy that maps previously learned policies to novel scenarios. These results enrich our understanding of human reinforcement learning in complex environments with changing task demands.

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Fig. 1: Overview of theoretical setup and experiments.
Fig. 2: Overview and results of experiment 1.
Fig. 3: Overview and results of experiment 2.
Fig. 4: Overview and results of experiment 3.
Fig. 5: Results of preregistered experiment 4.

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Data availability

Anonymized participant data and model simulation data are available at https://github.com/tomov/MTRL.

Code availability

Code for all models and analyses is available at https://github.com/tomov/MTRL.

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Acknowledgements

The authors thank N. Franklin and W. Yang for helpful discussions. This research was supported by the Toyota Corporation, the Office of Naval Research (award N000141712984), the Harvard Data Science Initiative and the Center for Brains, Minds and Machines (CBMM), funded by NSF STC award CCF-1231216. The funders had no role in study design, data collection and analysis, decision to publish or preparation of the manuscript.

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Author notes

  1. Contributed equally. Momchil S. Tomov and Eric Schulz

Authors and Affiliations

  1. Program in Neuroscience, Harvard Medical School, Boston, MA, USA

    Momchil S. Tomov

  2. Center for Brain Science, Harvard University, Cambridge, MA, USA

    Momchil S. Tomov & Samuel J. Gershman

  3. Max Planck Institute for Biological Cybernetics, Tübingen, Germany

    Eric Schulz

  4. Department of Psychology, Harvard University, Cambridge, MA, USA

    Eric Schulz & Samuel J. Gershman

  5. Center for Brains, Minds and Machines, Cambridge, MA, USA

    Samuel J. Gershman

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  1. Momchil S. Tomov
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  3. Samuel J. Gershman
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Contributions

M.S.T. and E.S. contributed equally. M.S.T., E.S. and S.J.G. conceived the experiments, M.S.T. and E.S. conducted the experiments and analysed the results. All authors wrote the manuscript.

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Correspondence to Momchil S. Tomov or Eric Schulz.

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The authors declare no competing interests.

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Supplementary Information with additional analyses and plots, Supplementary Figs. 1–6 and Supplementary References.

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Tomov, M.S., Schulz, E. & Gershman, S.J. Multi-task reinforcement learning in humans. Nat Hum Behav 5, 764–773 (2021). https://doi.org/10.1038/s41562-020-01035-y

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