Of Two Minds, One Consciousness

Studies of split-brain patients provide insight into how we form thoughts--specifically how the left brain will create its own narrative based on information it never received. Christie Nicholson reports.

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[Below is the original script. But a few changes may have been made during the recording of this podcast.]

We know from neuroscientists that the right brain deals with the immediate moment—the facts and details—whereas the left brain attempts to interpret those facts, events, observations.

Most intriguing is how the left brain, in its need to interpret, will make up stories even without any information.

Michael Gazzaniga of the University of California, Santa Barbara, affected the mood of a split-brain patient. He influenced their right brain with a stimulus to laugh, and then asked why they were cracking up.

The speech center, located in the left brain (which never received the humorous stimuli), had no idea why the patient was laughing—but still, came up with an explanation: "You guys are so funny!"

Gazzaniga then presented a visual stimulus to the right brain, attempting to make the patient feel angry.

He asked them to explain why they were feeling that way. The patient denied seeing anything, yet said they felt upset and said it was the experimenter who was making them upset.

Gazzaniga recounts this and other studies in the June/July issue of Scientific American Mind.

But perhaps even more profound, he explains how, even though split-brain patients have isolated hemispheres, they experience a unified consciousness—that is, feel as though they are of one mind.

-- Christie Nicholson


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