© 2014 IEEE.A notion of phenomenological percolation for Conceptual Structures associated to Complex Systems (CS) is proposed. This process on concept lattices (from Formal Concept Analysis) consists in the allocation of (non-previous) objects in the lattice, which can induce its extension. The aim is to study the robustness of this conceptual structure when facing unexpected changes (represented by the new object) in the CS it models. Results show that concept lattices associated to CS present more robustness than concept lattices modeling other kind of systems.