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Modeling human decision-making in generalized Gaussian multi-armed bandits

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Paul Reverdy, Vaibhav Srivastava and Naomi Ehrich Leonard

(2014), *Proceedings of the IEEE*, Vol. 102, No. 4, 544-571.

Paper at Proc. IEEE
Paper at arXiv:1307.6134v2 [cs.LG]
We present a formal model of human decision-making in explore-exploit tasks using the context of multi-armed bandit problems,
where the decision-maker must choose among multiple options with uncertain rewards. We address the standard multi-armed bandit problem,
the multi-armed bandit problem with transition costs, and the multi-armed bandit problem on graphs. We focus on the case of Gaussian
rewards in a setting where the decision-maker uses Bayesian inference to estimate the reward values. We model the decision-maker's
prior knowledge with the Bayesian prior on the mean reward. We develop the upper credible limit (UCL) algorithm for the standard
multi-armed bandit problem and show that this deterministic algorithm achieves logarithmic cumulative expected regret, which is optimal
performance for uninformative priors. We show how good priors and good assumptions on the correlation structure among arms can greatly
enhance decision-making performance, even over short time horizons. We extend to the stochastic UCL algorithm and draw several
connections to human decision-making behavior. We present empirical data from human experiments and show that human performance is
efficiently captured by the stochastic UCL algorithm with appropriate parameters. For the multi-armed bandit problem with transition
costs and the multi-armed bandit problem on graphs, we generalize the UCL algorithm to the block UCL algorithm and the graphical block
UCL algorithm, respectively. We show that these algorithms also achieve logarithmic cumulative expected regret and require a
sub-logarithmic expected number of transitions among arms. We further illustrate the performance of these algorithms with numerical examples.

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