A determination regarding whether to intervene in a dialog to provide system-initiated assistive information involves monitoring a dialog between at least two participants and capturing data from a dialog environment containing at least one of the participants. The captured data represent the content of the dialog and physiological data for one or more participants. Assistive information relevant to the dialog and participants is identified, and the captured data are used to determine an intervention index of delivering the assistive information to one or more participants during the dialog. This intervention index is then used to determine whether or not to intervene in the dialog to deliver the assistive information to one or more participants.