According to Simon (1995: 507), "the very complex behaviour of the human expert are produced by a small number of rather simple processes". More precisely, experts would essentially use recognition skills (based on a great amount of knowledge on the activity to process), that they would combine with heuristic research skills (based on a set of research techniques). This would then explain their rapidity and their efficiency in most cognitive activities. According to Ericsson and Lehmann (1996), experts are distinguished from novices by their capacity to adapt themselves in an optimal and maximal manner to constraints linked to the task, whatever it is.