What Split-Brain Patients Reveal About Consciousness

Split-brain patients are people who have undergone a corpus callosotomy — a surgical severing of the corpus callosum, the bundle of nerves connecting the brain's left and right hemispheres. This was historically used to treat severe epilepsy. Starting in the 1960s, neuroscientists Roger Sperry and Michael Gazzaniga studied these patients and made a famous discovery: the two hemispheres can process information independently, and the left hemisphere (which controls speech in most people) will confidently invent plausible-sounding explanations for behaviors actually driven by the right hemisphere — a phenomenon called "confabulation" or "the interpreter." This raised deep questions about whether severing the connection creates two separate conscious agents, and what that means for the unity of ordinary experience. The article discusses ongoing debates about consciousness, the binding problem (how the brain creates a single experience from separate inputs), and recent research using blindsight patients and split-brain studies to test theories of conscious awareness.