Split-brain patients present a fascinating paradox in neuroscience: they behave as if there are two conscious minds within a single person’s head.
These patients have undergone a surgical procedure to sever their corpus callosum, the bundle of nerve fibers connecting the two hemispheres of the brain, typically as a treatment for severe epilepsy.
Split-Brain Experiments
Experiments conducted in the twentieth century on these patients revealed how the left hemisphere of the human brain controls speech, while the right hemisphere — having control over the left half of the visual field — is effectively mute, yet still possesses its own segmented conscious experience of the world.
One particularly revealing experiment involved splitting the patient’s visual field so each eye saw a different image. When asked what they saw, the patient would describe what the right eye saw (controlled by the left hemisphere). However, when asked to draw what they saw with their left hand, they would depict what the left eye saw — information they could not verbalize.
Perhaps most intriguingly, when shown what they had drawn, patients would often confabulate a story to explain their drawing — a phenomenon strikingly similar to how an AI chatbot might hallucinate an answer to a prompt rather than admit a lack of knowledge.
Implications for Consciousness
These experiments challenge our notion of a single, unified conscious experience. They demonstrate how easily what we perceive as a cohesive consciousness can become disjointed when the usual pathways of inter-hemispheric communication are disrupted.
The Combination Problem
This fragmentation of consciousness highlights what philosophers call the “combination problem” in panpsychism.
How do we arrive at a single unified consciousness given a collection of disparate, simpler forms of consciousness?
One potential answer may lie in the concept of alignment. When all parts of the brain can communicate and work together effectively, does this create a cohesive conscious experience?
Turtles All the Way Down
This leads to a provocative idea: is consciousness a hierarchy?
We might imagine single particles possessing a rudimentary form of consciousness, “working together” to form atoms and molecules. These, in turn, collaborate to form more complex chemical structures, and so on up the chain of complexity until we reach the human mind — an intricate ecosystem of independent parts aligned to create a cohesive conscious experience.
If this model holds true, where does it end? As technology advances, we might speculate on the possibility of humans communicating efficiently through some sort of brain interface. Could this lead to the creation of a hive-mind with a single, unified consciousness that transcends individual human minds?
Source: Galileo’s Error Foundations for a New Science of Consciousness