  The integration of information from many sources is an important feature of consciousness and, as noted above (section 6.4), is often cited as one of its major functions.  Content integration plays an important role in various theories especially global workspace theory (section 9.3).  However, a proposal by the neuroscientist Giulio Tononi (2008) goes further in identifying consciousness with integrated information and asserting that information integration of the relevant sort is both necessary and sufficient for consciousness regardless of the substrate in which it is realized (which need not be neural or biological).  According to Tononi's Integrated Information Theory (IIT), consciousness is a purely information-theoretic property of systems.  He proposes a mathematical measure φ that aims to measure not merely the information in the parts of a given system but also the information contained in the organization of the system over and above that in its parts. φ thus corresponds to the system's degree of informational integration.  Such a system can contain many overlapping complexes and the complex with the highest φ value will be conscious according to IIT.