While the nature of consciousness may remain elusive, neuroscientists have made significant strides in understanding it. The journey is far from over.

“Numerous theories exploring consciousness exist, so further theories may be superfluous,” states Oscar Ferrante, a neuroscientist at the University of Birmingham.

If you seek an explanation for how our brains create subjective experiences, you might explore adaptive resonance theory or dynamic core theory. Additionally, the theory of primary expression and semantic pointer competition should not be overlooked. A 2021 survey identified 29 distinct theories of consciousness.

Dr. Ferrante is part of a group aiming to consolidate this proliferation of theories. Yet, they face challenges due to the typical approach scientists take towards consciousness studies. They propose theories, conduct experiments, gather evidence, and often claim their theory reigns supreme.

“We are discouraged from abandoning our ideas,” remarked Lucia Meloni, a neuroscientist at the Max Planck Institute for Empirical Aesthetics in Frankfurt, Germany.

Seven years ago, Dr. Meloni and 41 other scientists launched an extensive study on consciousness to break this cycle. Their goal was to unite rival groups to design an experiment that would assess the predictive power of both theories regarding conscious experiences in the brain.

The Cogitate Consortium team recently published their findings in Nature. However, this study encountered the same contentious conflicts they aimed to avoid.

Dr. Meloni and like-minded colleagues started planning their research in 2018, adopting a strategy known as hostile collaboration—where scientists with opposing theories partner with neutral researchers. They selected two theories for examination.

The first, known as the Global Neuronal Workspace Theory, was introduced in the early 2000s by Collège de France’s Stanislas Dehaene. This theory posits that our conscious experiences arise when key brain areas distribute sensory information across the brain.

The second theory, Integrated Information Theory, developed by the University of Wisconsin’s Giulio Tononi, does not link consciousness to specific brain regions. Instead, it begins with essential characteristics of conscious experience, such as feeling unique and possessing rich, coherent details. Madeleine.

Researchers then examined which physical networks, such as the brain, could facilitate this experience. They concluded that a substantial amount of information must be processed across various networks and integrated to form a cohesive experience.

The Cogitate Consortium’s experiment aimed to potentially test both theories, garnering support from proponents of both.

“This collaboration was significant as it was the first attempt to reconcile differences rather than engage in isolated pursuits,” noted Dr. Meloni.

However, they knew that hostile collaboration would require substantial effort. They enlisted many young researchers, including Dr. Ferrante, and spent two years designing experiments and setting up lab equipment. By the latter half of 2020, they began scanning the brains of 267 volunteers across eight labs in the US, Europe, and China.

Volunteers played video games designed to gauge their conscious perception. In one game, participants were tasked with catching a colored disc when it changed to striped. Occasionally, blurred faces appeared on the screen, prompting volunteers to indicate what they had noticed.

To capture data comprehensively, researchers employed three distinct methods to measure brain activity.

Some volunteers who had undergone surgery for epilepsy consented to have electrodes temporarily placed in their brains. The second group utilized fMRI to assess blood flow in the brain, while a third group underwent magnetic EEG testing to record the brain’s magnetic field.

By 2022, the researchers shifted focus to data analysis. The three techniques produced consistent results. Both theories made accurate predictions regarding brain activity during conscious experiences, but also had incorrect predictions.

“Both theories are incomplete,” remarked Dr. Ferrante.

In June 2023, Dr. Meloni presented the findings at a New York conference, and the Cogitate Consortium submitted their results for publication, hoping to see their work in print.

Hakwan Lau, a neuroscientist at Sungkyunkwan University, was invited to review the paper but made a critical assessment. He believed the consortium failed to clearly outline where in the brain they would test predictions for each theory.

“Making a compelling case that the project tests theories meaningfully is challenging,” Dr. Lau stated in a July review.

Having developed his own consciousness theory, Dr. Lau published an evaluation online in August, and later co-authored an open letter criticizing both the Cogitate experiments and Integrated Information Theory. A total of 124 experts endorsed the letter.

The group labeled “IIT agree” directed much of its critique at integrated information theory, calling it pseudoscience in a recent analysis.

Critics highlighted that Integrated Information Theory extends beyond just a brain function theory—implying that a system capable of integrating information, even a plant, may possess some level of consciousness.

Critics contended that the Cogitate Consortium’s experiment failed to address the foundational aspects of the theory, thereby not adequately challenging its claims. “As researchers, we must safeguard the public from scientific misinformation,” Dr. Lau and his colleagues asserted.

Their letter, published online in September 2023, ignited a flurry of debate on social media. The authors later provided a commentary to elucidate their concerns, which was featured the following month in Nature Neuroscience.

In response, Dr. Tononi and his colleagues, in a published letter defended IIT, claiming that the critics’ letters were “full of enthusiasm and lacking in facts,” and asserting that the new commentary merely aimed to reshape the discussion.

Meanwhile, the Cogitate Consortium paper continued through the peer review process. Upon its release on Wednesday, it drew a spectrum of responses.

Anil Seth, a neuroscientist at the University of Sussex, expressed admiration for the study’s scale and the identification of shortcomings in both theories. “I’m pleased to see that,” he remarked. “That’s an impressive achievement.”

However, some critics of IIT continued to voice concerns. Joel Snyder, a psychologist at the University of Nevada, Las Vegas, noted that the predictions from each team might have been generated by alternative theories, indicating the experiment wasn’t a true test of either.

“This is likely to cause confusion,” Dr. Snyder commented.

Dr. Lau reflected in an email that the recent research does not appear to have narrowed down the numerous theories of consciousness. “Recent discussions leave me with the impression that these issues haven’t significantly advanced any theory,” he wrote.

Nonetheless, Dr. Seth acknowledged the value of testing competing theories, even if scientists are reluctant to discard their ideas. “The best outcome of a successful hostile collaboration is that it may lead others to reconsider their views,” he stated.