Back in March, I did a post on a proposed Templeton Foundation project to test major scientific theories of consciousness. The idea was to start with a head to head competition between the integration information theory (IIT) and global workspace theory (GWT). Apparently that project got funded and, according to a Science Magazine article, there are now active plans to move forward with it.
The first two contenders are the global workspace theory (GWT), championed by Stanislas Dehaene of the Collège de France in Paris, and the integrated information theory (IIT), proposed by Giulio Tononi of the University of Wisconsin in Madison. The GWT says the brain’s prefrontal cortex, which controls higher order cognitive processes like decision-making, acts as a central computer that collects and prioritizes information from sensory input. It then broadcasts the information to other parts of the brain that carry out tasks. Dehaene thinks this selection process is what we perceive as consciousness. By contrast, the IIT proposes that consciousness arises from the interconnectedness of brain networks. The more neurons interact with one another, the more a being feels conscious—even without sensory input. IIT proponents suspect this process occurs in the back of the brain, where neurons connect in a gridlike structure.
To test the schemes, six labs will run experiments with a total of more than 500 participants, costing the foundation $5 million. The labs, in the United States, Germany, the United Kingdom, and China, will use three techniques to record brain activity as volunteers perform consciousness-related tasks: functional magnetic resonance imaging, electroencephalography, and electrocorticography (a form of EEG done during brain surgery, in which electrodes are placed directly on the brain). In one experiment, researchers will measure the brain’s response when a person becomes aware of an image. The GWT predicts the front of the brain will suddenly become active, whereas the IIT says the back of the brain will be consistently active.
Tononi and Dehaene have agreed to parameters for the experiments and have registered their predictions. To avoid conflicts of interest, the scientists will neither collect nor interpret the data. If the results appear to disprove one theory, each has agreed to admit he was wrong—at least to some extent.
The whole thing has a bit of a publicity stunt feel to it. As I noted back in March, both of these theories make differing philosophical assumptions about what consciousness fundamentally is, and the authors of both theories used empirical data, as it existed at the time, when formulating their theory. So I’m not expecting the results to be overwhelmingly conclusive. (Although it’d be good to be proven wrong on this.)
What might be interesting is the front of the brain vs back of the brain thing. I’ve noted this debate before. Some scientists, notably people like Tononi and Christof Koch, see consciousness as concentrated in the back part of the brain, in the sensory processing regions including the temporal and parietal lobes. Others, such as Dehaene, Joseph LeDoux, and Hakwan Lau, think we don’t become conscious of something until it reaches the prefrontal cortex.
This also has relevance on the distinction between first order and higher order theories, that is, between theories that hold that the representations and processing in sensory regions are conscious ones, versus theories that hold that further “higher order” processing in the prefrontal cortex is necessary for us to be conscious of them.
Part of the difficulty is that scientists depend on subject self report to know when those subjects are conscious of something. However, self report requires the frontal lobes. There are protocols to minimize the confounding role of self report, such as comparing brain scans of people who see something and report being conscious of it with people who see the same thing but without the requirement to report it. But a first order advocate can always insist that any remaining frontal activations are superfluous, that all that’s needed for actual consciousness is the posterior activity.
My own money is that the frontal regions are important, perhaps crucial. But this is complicated. It’s possible for sensory information from the back part of the brain to trigger sub-cortical activity, such as habitual or reflexive action, without frontal lobe involvement. It’s even possible to remember what happened during that behavior and consciously retrieve it later, giving us the impression we were conscious of the event during the event, even if we weren’t.
But if we insist that consciousness must include emotional feelings, then I think the frontal lobes become unavoidable. The survival circuit activations that drive these feelings happen in subcortical regions in the front part of the brain, which have excitatory connections to the prefrontal cortex. Of course, you could insist that the felt emotions lie in those subcortical circuits rather than the cortex, but severing the connections between those circuits and the prefrontal cortex (like what reportedly used to happen with lobotomies) typically results in deadened emotions.
And all of this is aside from the fact that the introspection machinery is in the very front part of the prefrontal cortex (the frontal poles). Are we conscious of it if we can’t introspect it?
As I said, complicated. A lot of this will depend on the assumptions and definitions the experimenters are using.
Still, I’m curious on exactly what they plan to do to test the back versus front paradigms. If they do figure out a way to conclusively isolate conscious perception with one or the other, it might answer a lot of questions. And if they do plan to eventually move on to testing theories like local recurrent processing or higher order thought theories, this work might provide a head start.
What do you think? Am I being too pessimistic on whether these experiments will validate or falsify IIT or GWT? Or are these theories all hopelessly underdetermined, and we’ll still be arguing over them months after the experimental results are published?