 The maximally irreducible cause-effect repertoire of each concept within a conceptual structure specifies what the concept contributes to the quality of the experience, while its irreducibility formula_11 specifies how much the concept is present in the experience.According to IIT, an experience is thus an intrinsic property of a complex of mechanisms in a state.The calculation of even a modestly-sized system's formula_12 is often computationally intractable, so efforts have been made to develop heuristic or proxy measures of integrated information.