Joel Frohlich has an interesting article up at Aeon on the possibility of detecting consciousness. He begins with striking neurological case studies, such as the one of a woman born without a cerebellum, yet fully conscious, indicating that the cerebellum is not necessary for consciousness.
He works his way to the sobering cases of consciousness detected in patients previously diagnosed as vegetative, accomplished by scanning their brain while asking them to imagine specific scenarios. He also notes that, alarmingly, consciousness is sometimes found in places no one wants it, such as anesthetized patients.
All of which highlight the clinical need to find a way to detect consciousness, a way independent of behavior.
Frohlich then discusses a couple of theories of consciousness. Unfortunately one of them is Penrose and Hammeroff’s quantum consciousness microtuble theory. But at least he dismisses it, citing its inability to explain why the microtubules in the cerebellum don’t make it conscious. It seems like a bigger problem is explaining why the microtubules in random blood cells don’t make my blood conscious.
Anyway, his preferred theory is integrated information theory (IIT). Most of you know I’m not a fan of IIT. I think it identifies important attributes of consciousness (integration, differentiation, causal effects, etc), but not ones that are by themselves sufficient. It matters what is being integrated and differentiated, and why. The theory’s narrow focus on these factors, as Scott Aaronson pointed out, leads it to claim consciousness in arbitrary inert systems that very few people see as conscious.
That said, Frohlich does an excellent job explaining IIT, far better than many of its chief proponents. His explanation reminds me that while I don’t think IIT is the full answer, it could provide insights into detecting whether a particular brain is conscious.
Frohlich discusses how IIT inspired Marcello Massimini to construct his perturbational complexity index, an index used to asses the activity in the brain after it is stimulated using transcranial magnetic stimulation (TMS), essentially sending an electromagnetic pulse through the skull into the brain. A TMS pulse that leads to the right kind of widespread processing throughout the brain is associated with conscious states. Stimulation that only leads to local activity, or the wrong kind of activity, isn’t.
IIT advocates often cite the success of this technique as evidence, but from what I’ve read about it, it’s also compatible with the other global theories of consciousness such as global workspace or higher order thought. It does seem like a challenge for local theories, those that see activity in isolated sensory regions as conscious.
Finally, Frohlich seems less ideological than some IIT advocates, more open to things like AI consciousness, but notes that detecting it in these systems is yet another need for a reliable detector. I fear detecting it in alternate types of systems represents a whole different challenge, one I doubt IIT will help with.
But maybe I’m missing something?