How the Split Brain Undermines Our Understanding of Consciousness

Human higher-order cognition is not what it seems.

In my last post on Medium about the Problem with Consciousness, I outlined a bare-bone summary of the shortcomings and pitfalls of human consciousness; that our higher-order cognition that we perceive interprets our immediate environment and directs our moment-to-moment decisions and actions doesn’t actually do those things. Here I describe a series of studies from almost 50 years ago that blew open our understanding of consciousness.

An early indication that our consciousness is dispensable and even problematic comes from work to curb the deleterious effects of epilepsy. In epilepsy the seizure begins as a storm of neural activity localized in a specific brain region but can then spread throughout the brain leading to the acute seizure symptoms associated with the disease. Preventing the migration of this neural storm was achieved in the 1960s by a procedure called a commissurotomy that severed the corpus callosum, a thick band of nerves connecting the brain’s left and right hemispheres. (Drugs are now preferred to control epilepsy although brain ablation is sometimes still used in severe cases.) Disconnecting the two hemispheres isolated the neural storm to one side of the brain lessening the symptoms.