Abstract: Successive sections of a computer program of a user interactive system are carried out. A user presents successive verbal items such as answers, to verbal items such as questions presented by the system. Each question corresponds to a respective program section. The user item is recognized and a next machine item is presented, if possible and appropriate. The recognizing is evaluated, and on the basis of the evaluating a progress score is kept. If the progress score attains a particular level, the system enables an operator to intervene in the dialogue in an unobtrusive manner. If a plurality of dialogs are supervised in parallel, the enabling is on the basis of a progress ranking among the dialogs. The intervention may be realized by emulating a user item in the form of speech or in the form of a mechanically entered user item.