“…As a consequence of technological development, the human operator of the industrial process control room is becoming less and less involved in manual control tasks, while at the same time, realizing ever more complex cognitive tasks to solve problems (Rasmussen, 1986;Moray 1986). In complex processes, the tendency has been to assist the operator by "assistance systems" (see for instance the works of Helander, 1988;Millot, 1988;Boy, 1988;1990;Tendjaoui et al, 1991 ;Kolski et al, 1992, and so on). These new systems can be based -or not-on Artificial Intelligence approach, such as expert systems.…”