Reinforcement learning for discounted values often loses the goal in the application to animal learning

The impulsive preference of an animal for an immediate reward implies that it might subjectively discount the value of potential future outcomes. A theoretical framework to maximize the discounted subjective value has been established in the reinforcement learning theory. The framework has been successfully applied in engineering. However, this study identified a limitation when applied to animal behavior, where in some cases, there is no learning goal. Here a possible learning framework was proposed that is well-posed in any cases and that is consistent with the impulsive preference.