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“Split-brain experiments are genuinely unsettling. In these studies, patients had the connection between their brain’s left and right hemispheres surgically severed, usually as a treatment for severe epilepsy. Scientists then gave them different tasks to understand how each half of the brain functioned independently. The two hemispheres of the brain don’t process information the same way. Certain functions, like speech and language, are usually centered in the left hemisphere, while other tasks are handled more by the right. The brain isn’t perfectly symmetrical in terms of function. The most famous split-brain experiments were conducted by researchers like Roger Sperry and Michael Gazzaniga on patients whose corpus callosum, the bridge connecting both hemispheres, had been surgically cut.”
“One of the best-known experiments involved vision. If an image was flashed only to the patient’s left visual field, the information went to the right hemisphere. Since speech is usually controlled by the left hemisphere, the patient often couldn’t verbally say what they saw.
However, their left hand, which is controlled by the right hemisphere, could still point to or pick up the correct object. In other words, the brain knew the answer, but the speaking part of the brain couldn’t explain it. One especially disturbing experiment involved showing a command only to the patient’s right hemisphere, something like: “Walk over there.” The patient would then stand up and start walking.
But when researchers asked why they were doing it, the speaking left hemisphere had never actually seen the command because the hemispheres could no longer communicate. Instead of saying “I don’t know,” the patient would confidently give a completely made-up explanation like: “I’m going to get a Coke.”
The unsettling part is that the patient wasn’t lying or joking. They genuinely believed the explanation they gave. Their brain automatically created a reason that felt coherent and real to them, even though the actual cause of the action was inaccessible to the part of the brain responsible for speech.
Essentially, the brain would rather invent a believable story than admit it doesn’t know why it did something. That’s what made these experiments so influential and disturbing. They suggested that humans can sincerely experience completely invented explanations as genuine motives.”