We designed Procope as a computational architecture system to model users’ Knowledge through semantic networks of action (S.N.O.A.) and to simulate with the computer the carrying out of tasks issued of varied S.N.O.A. where hierarchies of classes of objects are built using applied goals as properties of objects. Procope software helps formalize a unique description for procedural and declarative knowledge and can be put to various uses such as instructing subjects about how to use a device with the understanding of both “how to do it” and “how it works” as well as estimating the cognitive complexity of devices and simplifying interfaces. Two computer driven experiments attested the ability to improve subjects performance, when instructing novices with a documentation structured as the S.N.O.A. of an “Ideal User” (exp.1) or when decreasing the magnitude of the complexity values of a device (exp.2).