Science routinely proposes theories and then bombards them with data until only one remains. In the young science of consciousness, a dominant theory has yet to emerge. More than 20 are still taken seriously.
It’s not due to missing data. Since Francis Crick, the co-discoverer of the DNA double helix, legitimized consciousness as a subject of study more than three decades ago, researchers have used a variety of advanced technologies to examine the brains of test subjects and detect the signatures of neural activity that might reflect consciousness. The resulting avalanche of data has probably now destroyed at least the more flimsy theories.
Five years ago, the Templeton World Charity Foundation initiated a series of “controversial collaborations” to kick-start long-overdue fundraising. Last June, the results of the first of these collaborations were published, pitting two high-profile theories against each other: Global Neural Workspace Theory (GNWT) and Integrated Information Theory (IIT). Neither emerged as the overall winner.
The results, announced like the outcome of a sporting event at the 26th meeting of the Association for the Scientific Study of Consciousness (ASSC) in New York City, were also used to settle a 25-year bet between Crick’s longtime collaborator, the neuroscientist used Christof Koch of the Allen Institute for Brain Science and the philosopher David Chalmers from New York University, who coined the term “the hard problem” to challenge the assumption that we can explain the subjective feeling of consciousness by analyzing the brain’s circuits.
On stage at NYU’s Skirball Center, after rock music interludes, a rap performance about consciousness and the presentation of the results, the neuroscientist conceded the bet to the philosopher: the neural correlates of consciousness had not yet been nailed down.
Nevertheless, Koch announced: “It is a victory for science.”
But was that it? The event received mixed reviews. Some researchers point out that they have not been able to meaningfully test the differences between the two theories. Others highlight the project’s success in advancing consciousness science, both by providing large, novel, skillfully executed data sets and by inspiring other participants to engage in their own controversial collaborations.
The correlates of consciousness
When Crick and Koch published their seminal paper Their goal was to put consciousness, which had been the preserve of philosophers for 2,000 years, on a scientific basis. They argued that consciousness in its entirety was too broad and controversial a concept to serve as a starting point.
Instead, they focused on a scientifically understandable aspect of it: visual perception, which involves becoming aware of the color red, for example. The scientific goal was to find the circuits that correlated with this experience, or as they called it, the “neural correlates of consciousness.”
Deciphering the first stages of visual perception had already proven to be fertile ground for science. Patterns of light falling on the retina send signals to the visual cortex at the back of the brain. There, more than 12 different neural modules process the signals that correspond to edges, color and movement in the images. Their results combine to create a final dynamic picture of what we consciously see.
What made visual perception useful for Crick and Koch was that the final link in this chain – consciousness – could be separated from the rest. Since the 1970s, neuroscientists have known about people with “blindsight,” who have no visual experience due to damage to their brain and yet are able to move through a room without encountering obstacles. While they retain the ability to process an image, they lack the ability to be aware of it.