Global workspace theory, integrated information theory, higher-order theories, recurrent processing and predictive processing — what each claims, how they differ, and the adversarial collaborations testing them.
Sleep & Consciousness
Advanced
Theories of Consciousness
The Editors
August 3, 2026
3 min read
In plain English
Scientists have several competing theories of how the brain produces conscious experience. One says consciousness is information broadcast widely across the brain; another says it's about how integrated a system's information is; others focus on the brain representing its own states. Researchers are now running head-to-head experiments to test their predictions.
Advanced level: The detailed machinery — ions, receptors, circuits and methods. Read the linked concepts first.
Concepts to know first
Dozens of scientific theories of consciousness exist. A few dominate the research landscape.
Global workspace theory
Proposed by the psychologist Bernard Baars in 1988 and developed into a neural model by Stanislas Dehaene and Jean-Pierre Changeux, global workspace theory (GWT) likens the mind to a theatre: many specialised processes work unconsciously backstage, and information becomes conscious when it enters a "workspace" and is broadcast widely, becoming available for memory, report and decision-making. In the brain, this broadcast is thought to involve long-range connections linking prefrontal and parietal cortex. Dehaene's experiments describe "ignition": a sudden, sustained, brain-wide burst of activity when a stimulus crosses into awareness.
Integrated information theory
Giulio Tononi's integrated information theory (IIT), first proposed in 2004, starts from properties of experience itself (it is unified, specific, structured) and asks what physical systems could have them. Its answer: consciousness corresponds to integrated information, measured by a quantity called Φ (phi) — how much a system as a whole carries information beyond its parts. IIT predicts that consciousness depends especially on posterior cortex, and it implies that some simple systems may have a little consciousness while some powerful computers may have none. Critics consider its central measure impractical to compute and some of its implications implausible.
Higher-order and other theories
Higher-order theories (David Rosenthal, Hakwan Lau and others) hold that a mental state is conscious when the brain represents itself as being in that state — linking consciousness to metacognition and the prefrontal cortex. Recurrent processing theory (Victor Lamme) argues that feedback loops within sensory cortex suffice for experience. Predictive processing approaches (Anil Seth and others) see experience as the brain's best predictions about the world and the body.
Putting theories to the test
To break the stalemate, researchers have organised adversarial collaborations, in which proponents of rival theories agree in advance on experiments whose outcomes would support one and challenge the other. The COGITATE consortium tested GWT against IIT with fMRI, MEG and intracranial recordings; its results, published in Nature in 2025 after a preprint in 2023, challenged key predictions of both theories. The 2023 preprint also prompted an open letter from over a hundred researchers calling IIT "pseudoscience" — and a fierce backlash. The debate illustrates both how hard the problem is and how seriously the field now takes testing.
Everyday examples & things to try
Analogy
Theatre versus symphony
Global workspace theory is like a theatre: many actors backstage, and whoever steps into the spotlight is seen by the whole audience. Integrated information theory is more like a symphony: consciousness is how richly all the instruments' parts are woven into one inseparable whole.
Key takeaways
- Global workspace theory: consciousness is global broadcast ('ignition') across fronto-parietal networks.
- Integrated information theory: consciousness is integrated information (Φ), centred on posterior cortex.
- Adversarial collaborations like COGITATE (Nature, 2025) challenged predictions of both.
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