From the Phenomenology to the Mechanisms of Consciousness: Integrated Information Theory 3.0

Integrated Information Theory (IIT) 3.0 proposes that consciousness is identical to a maximally irreducible conceptual structure (MICS) generated by a physical system. Starting from phenomenological axioms—information (each experience is specific), integration (each experience is unified), and exclusion (each experience has unique borders and grain)—IIT formalizes postulates for how mechanisms like neurons must be configured to produce experience. The theory defines intrinsic information as differences that make a difference within a system and integrated information as information of a whole irreducible to its parts. A MICS specifies the quality of an experience, and integrated information (ΦMax) its quantity. The theory entails that consciousness is always about the system itself, that inactive elements can generate experience, and that feed-forward systems can be unconscious zombies functionally equivalent to conscious complexes.

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Abstract

This paper presents Integrated Information Theory (IIT) of consciousness 3.0, which incorporates several advances over previous formulations. IIT starts from phenomenological axioms: information says that each experience is specific – it is what it is by how it differs from alternative experiences; integration says that it is unified – irreducible to non-interdependent components; exclusion says that it has unique borders and a particular spatio-temporal grain. These axioms are formalized into postulates that prescribe how physical mechanisms, such as neurons or logic gates, must be configured to generate experience (phenomenology). The postulates are used to define intrinsic information as “differences that make a difference” within a system, and integrated information as information specified by a whole that cannot be reduced to that specified by its parts. By applying the postulates both at the level of individual mechanisms and at the level of systems of mechanisms, IIT arrives at an identity: an experience is a maximally irreducible conceptual structure (MICS, a constellation of concepts in qualia space), and the set of elements that generates it constitutes a complex. According to IIT, a MICS specifies the quality of an experience and integrated information ΦMax its quantity. From the theory follow several results, including: a system of mechanisms may condense into a major complex and non-overlapping minor complexes; the concepts that specify the quality of an experience are always about the complex itself and relate only indirectly to the external environment; anatomical connectivity influences complexes and associated MICS; a complex can generate a MICS even if its elements are inactive; simple systems can be minimally conscious; complicated systems can be unconscious; there can be true “zombies” – unconscious feed-forward systems that are functionally equivalent to conscious complexes.