While the nature of consciousness remains enigmatic, neuroscientists have plenty of theories to explore. In fact, there are numerous propositions regarding its workings.
“The realm of consciousness already has an abundance of theories; we don’t need more,” remarked Oscar Ferrante, a researcher from the University of Birmingham.
If you’re after an explanation for how our brains create personal experiences, you might want to dive into Adaptive Resonance Theory, or perhaps Dynamic Core Theory. And let’s not overlook First Order Representational Theory, along with semantic pointer competition theory. A survey from 2021 highlighted 29 distinct theories pertaining to consciousness.
Dr. Ferrante is part of a team of scientists who aim to condense this plethora of theories, ideally down to a single explanation. However, they encounter substantial obstacles due to the entrenched methods of researching consciousness: formulating a theory, gathering experimental evidence for it, and defending it against competing theories.
“We aren’t motivated to abandon our own theories,” claimed Lucia Melloni, a neuroscientist from the Max Planck Institute for Empirical Aesthetics in Frankfurt, Germany.
Seven years prior, Dr. Melloni, along with 41 fellow scientists, initiated a significant investigation into consciousness, hoping to change this trend. Their strategy was to unite two opposing camps to conduct an experiment determining how effectively both theories could predict brain activity during conscious experiences.
The team, known as the Cogitate Consortium, shared their findings recently in the journal Nature. However, the study ended up getting embroiled in the very disputes they aimed to sidestep.
Dr. Melloni and her group started drafting their study in 2018, aiming to apply a method called adversarial collaboration, where researchers with differing theories collaborate alongside impartial scientists. They selected two specific theories for evaluation.
The first, Global Neuronal Workspace Theory, was proposed in the early 2000s by Stanislas Dehaene and his team at the Collège de France in Paris. This theory posits that we achieve conscious awareness through key areas at the front of the brain disseminating sensory data throughout the brain.
The second theory, Integrated Information Theory, was developed by Giulio Tononi and his colleagues at the University of Wisconsin. This perspective doesn’t ascribe consciousness to specific brain areas performing designated functions. Instead, it starts from the fundamental elements of conscious experiences, noting their personal specificity and richness, forming a coherent and intricate whole — akin to Marcel Proust’s recollections triggered by the taste of a madeleine.
The researchers sought to identify what type of physical network — whether a brain or another system — could lead to such experiences. They deduced that creating integrated experiences necessitates processing vast amounts of information across various compartments that relay this info to each other.
The Cogitate Consortium outlined an experiment to assess both theories, gaining support from their respective advocates.
“It was quite encouraging, as it marked a new effort to reconcile their differences rather than engage in separate explorations,” Dr. Melloni reflected.
Nonetheless, she and her team realized that this collaboration would be a significant effort. They enlisted several junior researchers, including Dr. Ferrante, and spent a couple of years designing the experiment and conducting preliminary tests on their lab equipment. In late 2020, they started scanning the brains of 267 participants across eight labs in the U.S., Europe, and China.
Participants engaged in video games aimed at assessing their conscious awareness. In one of these games, they caught colored disks that zoomed by, while a blurry face occasionally appeared on the screen, prompting volunteers to press a button if they noticed it.
To ensure comprehensive data collection, the researchers utilized three different methods to monitor brain activity.
Some participants undergoing epilepsy surgery allowed electrodes to be temporarily placed in their brains. Another group was scanned using fMRI machines, which track blood flow, while the third group was examined with magnetoencephalography, which captures the brain’s magnetic fields.
By 2022, the researchers began analyzing their collected data. All three methods indicated similar overall trends. Both theories accurately predicted some aspects of brain activity during conscious visual experiences, but they also suggested incorrect predictions.
“Both theories have limitations,” noted Dr. Ferrante.
In June 2023, Dr. Melloni presented the findings at a conference in New York, and the Cogitate Consortium submitted their results for publication in Nature.
Hakwan Lau, a neuroscientist at Sungkyunkwan University who reviewed the study, gave it a critical response. He argued that the Cogitate Consortium failed to clearly define how and where in the brain each theory’s predictions would be tested.
“It’s hard to convincingly argue that the project effectively tests the theories in a substantial way,” Dr. Lau commented in his July review.
Dr. Lau, who has his own consciousness theory, publicly shared his assessment online in August. He also contributed to an open letter that criticized both the Cogitate experiment and Integrated Information Theory, gathering 124 signatures from fellow experts.
This group, termed “IIT-Concerned,” focused much of their critique on Integrated Information Theory, labeling it pseudoscience and referencing severe criticisms that have emerged in recent years.
Critics argued that Integrated Information Theory extends beyond just brain function; if any system capable of integrating information possesses consciousness, then even plants could be considered somewhat conscious.
They contended that the Cogitate Consortium’s experiment did not fulfill its ambitious claims as it did not evaluate the core components of the theory. “As researchers, we have a responsibility to shield the public from scientific misrepresentation,” Dr. Lau and his team stressed.
Their letter, posted online in September 2023, sparked a vigorous debate on social media. The authors later published a commentary detailing their concerns in Nature Neuroscience.
In response, Dr. Tononi and his colleagues dismissed the IIT-Concerned letter, arguing it was emotional rather than factual and that their commentary only attempted to improve their credibility under the guise of scientific philosophy.
Meanwhile, the Cogitate Consortium’s paper progressed through the peer review process. Once published on Wednesday, it received mixed reviews.
Anil Seth, a neuroscientist at the University of Sussex, praised the extensive nature of the study and its highlighting of both theories’ weaknesses. “I’m thrilled to see this. It’s a remarkable piece of work,” he remarked.
However, the IIT-Concerned critics maintained their stance. Joel Snyder, a psychologist from the University of Nevada, Las Vegas, expressed that each team’s predictions could have potentially stemmed from alternative theories, thus making the experiment less specific.
“It’s likely to create confusion,” Dr. Snyder cautioned.
In an email, Dr. Lau noted that the new study appeared not to have narrowed down the vast array of consciousness theories. “From recent conversations, it seems these debates haven’t impacted the theories,” he stated.
Nonetheless, Dr. Seth perceived merit in comparing theories, even if it doesn’t compel scientists to dismiss their concepts. “The best outcome from a fruitful adversarial collaboration is that others might reconsider their viewpoints,” he mentioned.
