The extraction of knowledge is sometimes seen as a technical reference to the conception of the specialist systems and of systems based on knowledge. The present paper intends to present some reflections designed to provide greater psychological insights to this problem. In this work, I try to show how the problem knowledge extration is understood by Ergonomic and by Artificial Intelligence, how knowledge can be obtained throught different objectives, and finally, I analyze the domain of construction of a help system for decision making. The latter objective is emphasized because of its relation to Cognitive Ergonomics which in turn stresses multiple levels of activity regulation. These levels and kinds of knowledge with which the operator deals must be understood before we can approach the methodological questions converning the acess to knowledges itself.
Cognitive simulation; ergonomic; cognitive processes; problem solving