Split-brain experiments reveal that the brain may invent reasons for actions when the true cause is unavailable to verbal centers.
The Science of the Split Brain
Split-brain experiments were conducted on patients who had the corpus callosum—the bridge connecting the brain's left and right hemispheres—surgically severed to treat severe epilepsy. Researchers including Roger Sperry and Michael Gazzaniga used these patients to study independent hemispheric processing. Speech and language functions are typically lateralized to the left hemisphere, while the right hemisphere handles other tasks.
A Classic Vision Experiment
In a classic vision experiment, an image was flashed to the patient's left visual field, processing in the right hemisphere. Because speech is usually controlled by the left hemisphere, the patient could not verbally identify the image, but could point to or pick up the correct object with the left hand (controlled by the right hemisphere).
The Confabulation Example
When a command like "Walk over there" was presented only to the right hemisphere (by controlling visual field exposure), the patient would stand up and walk. When asked why they were doing so, the left hemisphere (unaware of the command) would fabricate an explanation, e.g., "I'm going to get a Coke." The patient appeared to genuinely believe this explanation, demonstrating that the brain can automatically create a coherent narrative without access to the actual cause.
Broader Implications
The experiments suggest that the brain may invent reasons for actions when the true cause is unavailable to verbal centers, and individuals can sincerely experience these fabrications as genuine motives. This has been influential in understanding consciousness and self-deception.