1. A computer-implemented method, comprising: receiving, by a computing device, a user-statement from a user during a simulated conversation with the user; determining a set of automatic-statements that each responds to the user-statement; determining a set of behavior-characteristics associated with the user; computing relevance scores for the automatic-statements based on the behavior-characteristics, wherein a respective relevance score indicates an outcome quality that the user is likely to perceive for the automatic-statement as a response to the user-statement, wherein computing the respective relevance score for a respective automatic-statement involves computing a template-relevance score using a response-prediction function that takes as input a response template and the user's behavior-characteristics, and wherein the template-relevance score indicates how well the response template matches a conversation style for a user having the behavior characteristics; selecting an automatic-statement that has a highest relevance score from the set of automatic-statements; and providing the selected automatic-statement to the user.