The present disclosure relates to an information processing device, an information processing method, a program, and an information processing system that enable the reinforcement of a behavior to be reinforced, without making a user conscious of the reinforcement. A quest is presented to a user so as to encourage a behavior to be reinforced. Brain waves are measured when the user performs the behavior to be reinforced in response to the quest. Emotions are estimated on the basis of the brain waves. When an emotion determined to be a controlling emotion with the highest score, from among the emotions of the emotion estimation results, occurs as the controlling emotion a number of times exceeding a prescribed number of times, an avatar is changed in correspondence with the emotion deemed to be the controlling emotion. The present disclosure is applicable to long-term feedback technology.
INFORMATION PROCESSING DEVICE, INFORMATION PROCESSING METHOD, PROGRAM, AND INFORMATION PROCESSING SYSTEM