An experiment seven years in the making has uncovered new insights into the nature of consciousness and challenges two prominent, competing scientific theories: Integrated Information Theory (IIT) and Global Neuronal Workspace Theory (GNWT).

1. IIT suggests that consciousness emerges when information inside a system (like the brain) is highly connected and unified; and as long as the information remains unified, it will be consciously perceived.
2. GNWT suggests a network of brain areas spotlight important pieces of information in the brain—bringing it to the forefront of our minds—broadcasting it widely the moment it enters consciousness, and this produces conscious experience.

Researchers tested the two competing theories against one another in 2019 in a collaborative experiment involving human subjects. They published the findings today in Nature, and the study marks a pivotal moment in the goal to understand the elusive origins of consciousness.

“Adversarial collaboration fits within the Allen Institute’s mission of team science, open science and big science, in service of one of the biggest, and most long-standing, intellectual challenges of humanity: the Mind-Body Problem,” said Christof Koch, Ph.D., meritorious investigator at the Allen Institute. “Unravelling this mystery is the passion of my entire life.”

The Findings

Research showed that there’s functional connection between neurons in early visual areas of the brain (the areas that process vision, which are at the back of the brain) and the frontal areas of the brain, helping us understand how our perceptions tie to our thoughts. The findings de-emphasize the importance of the prefrontal cortex in consciousness, suggesting that while it’s important for reasoning and planning, consciousness itself may be linked with sensory processing and perception. In other words, intelligence is about doing while consciousness is about being.

The study also found that the back of the brain seems crucial for holding the specific details of what you see, like orientation. While the front part is also involved, especially in identifying the general category of an object, it might not be the main hub for all the visual specifics. This challenges the idea that the front part of the brain holds all the detailed content of our visual experience.

These discoveries have implications for how we understand consciousness. Furthermore, they may shed light on disorders of consciousness such as coma or vegetative state. Identifying where the footprints of consciousness are localized in the brain could help detect “covert consciousness” in unresponsive patients with severe brain injuries—a condition known to occur in about one-quarter of cases as reported in the New England Journal of Medicine last year.

Neither Theory Came Out on Top

IIT says consciousness comes from the interaction and cooperation of various parts of the brain as they work together to integrate information, like teamwork. The study, however, did not find enough sustained connections in the back of the brain to support this idea. GNWT supports the idea that consciousness happens in the front of the brain, but the study didn’t find enough support for this idea either.

“It was clear that no single experiment would decisively refute either theory. The theories are just too different in their assumptions and explanatory goals, and the available experimental methods too coarse, to enable one theory to conclusively win out over another,” said Anil Seth, Ph.D., a professor of cognitive and computational neuroscience at the University of Sussex. “Having said all this, the findings of the collaboration remain extremely valuable – much has been learned about both theories and about where and when in the brain information about visual experience can be decoded from.

The study involved 256 subjects, which is unprecedented for this kind of experiment. Researchers showed them various visual stimuli and then used three common human brain measurement tools that track blood flow as well as magnetic and electrical activity to study their brains while they looked at the stimuli.

The highly collaborative experiment is the result of a large-scale, open science collaboration that began at a workshop at the Allen Institute in 2018. This innovative approach brought together researchers with differing perspectives to test two theories in a collaborative, yet critical, environment aimed at reducing confirmation bias and accelerating scientific progress.

“Adversarial collaborations are a powerful social process, little used because of their challenging nature, seeking to coordinate the research and associated protocols across many, independent laboratories, and competitive individuals,” said Koch. “The bio-medical field could hugely profit by more such ‘friendly’ competition among theories—neurobiological or others. But it requires a great deal of cooperation and constant work to keep everyone aligned.”