The present disclosure relates to an information processing system, an information processing method, and an information processing device that make it possible to perform learning adaptively to changes in an external environment and circumstances. A learning section learns results of action selection made by a system in response to input information. An input information assessment section assesses a risk of the input information to the system. A first parameter calculation section calculates a first parameter representing stress on the system according to an assessed value of the input information. The learning section changes learning efficiency according to the first parameter. The technology according to the present disclosure is applicable, for example, to an information processing system that performs machine learning.