Abstract: An illustrative frustration processing system modifies the operation of a target system to improve its performance. In one case, the frustration processing system receives express indications that a user is frustrated in the course of interacting with the target system. The frustration processing system responds to these indications by modifying the operation of the target system to reduce the likelihood that the user will be frustrated in the future. The frustration processing system can modify the operation of the target system by applying a policy to the target system. The policy, in turn, is created using a prediction model. The prediction model predicts when a user is likely to be frustrated based on the user's prior indications of frustration.