A normative account of choice history effects in mice and humans

Choice history effects describe how future choices depend on the history of past choices. Choice history effects are typically framed as a bias rather than an adaptive phenomenon because the phenomenon generally degrades reward rates in experimental tasks. How-ever, in natural habitats, choices made in the past constrain choices that can be made in the future. For foraging animals, the probability of obtaining a reward in a given patch depends on the degree to which the animals have exploited the patch in the past. One problem with many experimental tasks that show choice history effects is that such tasks artificially decouple choice history from its consequences in regard to reward availability over time. To circumvent this, we used a variable interval (VI) reward schedule that reinstates a more natural contingency between past choices and future reward availability. By manipulating first- and second-order statistics of the environment, we dissociated choice history, reward history, and reaction times. We found that choice history effects reflect the growth rate of the reward probability of the unchosen option, reward history effects reflect environmental volatility, and reaction time reflects overall reward rate. By testing in mice and humans, we show that the same choice history effects can be generalized across species and that these effects are similar to those observed in optimal agents. Furthermore, we develop a new reinforcement learning model that explicitly incorporates choice history over multiple timescales into the decision process, and we examine its predictive adequacy in accounting for the associated behavioral data. We show that this new variant, known as the double trace model, has a higher predictive adequacy of choice data, in addition to better reward harvesting efficiency in simulated environments. Finally, we show that the choice history effects emerge in optimal models of foraging in habitats with diminishing returns, thus linking this phenomenon to a wider class of optimality models in behavioral ecology. These results suggests that choice history effects may be adaptive for natural contingencies between consumption and reward availability. This concept lends credence to a normative account of choice history effects that extends beyond its description as a bias.