1. A machine-implemented method for changing an interaction policy in a processing device, the method comprising: determining whether values of any of a plurality of parameters are updated, each of the plurality of parameters representing at least one of a user preference or contextual information with respect to use of the processing device; selecting, based on the values of the plurality of parameters, an interaction policy from a plurality of predefined interaction policies included in the processing device, each of the plurality of predefined interaction policies being associated with a respective dialog behavior for the processing device, the selected interaction policy determining a better dialog behavior for the processing device than a previous interaction policy; and activating the selected interaction policy.