To date, user participation in the reasoning processes of expert systems has been largely limited to probing expert reasoning or adding limited information. The user may only ask why the system requested more information and how it arrived at its advice. Research into extending the capabilities of expert systems [1, 2, 3] has so far failed to recognize the need to permit the full range of interactions possible when humans engage in the normal giving and getting of advice. input and human expert response.

From the radio show we collected twelve and one-half hours of user-expert interaction, involving 120 callers. An examination of these protocols reveals a regular pattern of interaction, which we describe as negotiation, the process whereby people arrive at a conclusion by means of a discussion. Rarely does a caller simply state a problem and passively listen to the expert's response. Rather the caller actively participates in the definition and resolution of the problem. Caller and expert must often negotiate to determine the statement of a problem the expert can solve and the statement of a solution the expert can support and the caller accept--and, ideally, understand. They may also need to negotiate a common understanding of terminology, a common set of world or domain beliefs, or an acceptable justification for the solution.