Integrated information theory (IIT)
This page delivers no verdict; it presents claims and evidence with their sources. No theory in science is absolute. Method
For everyone
According to this theory, proposed by Giulio Tononi in 2004, consciousness is a system's capacity to generate integrated information over and above its parts. This capacity is measured by a quantity called Φ (phi). On the theory, consciousness is tied to tightly connected structures in posterior regions of the brain and is not unique to brains. Some researchers regard it as a principled theoretical basis for consciousness, while others criticise it on the grounds that its core claims cannot be tested.
For specialists
IIT starts from the basic properties of experience (intrinsic existence, composition, information, integration, exclusion) and derives the conditions a physical system must meet. Computing Φ exactly is practically impossible for large systems. The theory leads to counter-intuitive consequences, such as some simple but integrated networks having a degree of consciousness. In the clinic, the related "zap-and-zip" perturbational complexity index (PCI) is used to estimate levels of consciousness.
Claims
- Consciousness is identical to the amount of integrated information (Φ) a system has that cannot be reduced to its parts.[1]
Evidence
Supporting
In the preregistered adversarial experiment, the presence of information about conscious content in posterior regions of the brain agreed with some of the theory's predictions.[2]
Challenging
In the same experiment, the sustained synchronisation in posterior regions predicted by the theory was not observed for the duration of conscious perception.[2]
Positions
- Researchers who signed a critical letter (2023, published 2025)
- IIT's core claims are untestable even in principle, so it should not be treated as a scientific theory.[3]
- Proponents of the theory
- IIT has testable predictions that have been tested in preregistered experiments; its counter-intuitive consequences deserve to be taken seriously as claims about the nature of consciousness.[2]
Connections
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Sources
- Article (2004). An information integration theory of consciousness. BMC Neuroscience 5, 42DOI 10.1186/1471-2202-5-42archive
- Article (2025). Adversarial testing of global neuronal workspace and integrated information theories of consciousness. Nature 642, 133–142DOI 10.1038/s41586-025-08888-1archive
- Article (2025). What makes a theory of consciousness unscientific?. Nature Neuroscience 28, 689–693DOI 10.1038/s41593-025-01881-xarchive
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Cite this page
Athena contributors. (2026). Integrated information theory (IIT). Athena: The tree of human knowledge. Retrieved November 1, 2026, from https://latifkedi.github.io/athena/en/d/butunlesik-bilgi/
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title = {Integrated information theory (IIT)},
author = {{Athena contributors}},
year = {2026},
howpublished = {\url{https://latifkedi.github.io/athena/en/d/butunlesik-bilgi/}},
note = {Athena: The tree of human knowledge. Accessed: 2026-11-01}
}Added: September 28, 2026 · Last changed: September 28, 2026 · Page history