Integrated information theory
is often computationally intractable,[9] so efforts have been made to develop heuristic or proxy measures of integrated information.
[13] In 2021, Angus Leung and colleagues published a direct application of IIT's mathematical formalism to neural data.
[14] To circumvent the computational challenges associated with larger datasets, the authors focused on neuronal population activity in the fly.
To solve this problem, Daniel Toker and Friedrich T. Sommer have shown that the spectral decomposition of the correlation matrix of a system's dynamics is a quick and robust proxy for the minimum information partition.
and conceptual structure is relatively straightforward, its high time complexity makes it computationally intractable for many systems of interest.
[9] Heuristics and approximations can sometimes be used to provide ballpark estimates of a complex system's integrated information, but precise calculations are often impossible.
Despite these challenges, researchers have attempted to use measures of information integration and differentiation to assess levels of consciousness in a variety of subjects.
was able to reliably discriminate between varying levels of consciousness in wakeful, sleeping (dreaming vs. non-dreaming), anesthetized, and comatose (vegetative vs. minimally-conscious vs. locked-in) individuals.
[19] IIT also makes several predictions which fit well with existing experimental evidence, and can be used to explain some counterintuitive findings in consciousness research.
[20] For example, IIT can be used to explain why some brain regions, such as the cerebellum do not appear to contribute to consciousness, despite their size and/or functional importance.
[23] Philosopher David Chalmers, famous for the idea of the hard problem of consciousness, has expressed some enthusiasm about IIT.
"[37] Tononi himself agrees with the assessment and argues that according to IIT, an even simpler arrangement of inactive logic gates, if large enough, would also be conscious.
However he further argues that this is a strength of IIT rather than a weakness, because that's exactly the sort of cytoarchitecture followed by large portions of the cerebral cortex,[38][39] specially at the back of the brain,[2] which is the most likely neuroanatomical correlate of consciousness according to some reviews.
[42] IIT has also been denounced by other members of the consciousness field as requiring "an unscientific leap of faith", but it is not clear that this is in fact the case if the theory is properly understood.
Philosopher Adam Pautz says "As long as proponents of IIT do not address these questions, they have not put a clear theory on the table that can be evaluated as true or false.
"[44] Neuroscientist Michael Graziano, proponent of the competing attention schema theory, rejects IIT as pseudoscience.
[2] Neuroscientists Björn Merker, David Rudrauf and Philosopher Kenneth Williford co-authored a paper criticizing IIT on several grounds.
[47] A letter published on 15 September 2023 in the preprint repository PsyArXiv and signed by 124 scholars asserted that until IIT is empirically testable, it should be labeled pseudoscience.
An anonymized public survey invited all authors from peer-reviewed papers published between 2013 and 2023 found by a query of Web of Science using "consciousness AND theor*".
