What Do Split-Brain Patients Tell Us About the Whole Brain?

November 21, 2010  |  brain, intelligence, neuroscience

In an experiment by Nobel Prize-winning psychologist Roger Sperry and his team, Joe is flashed pictures to both sides of the brain simultaneously. His left-brain sees a picture of a hammer and the right brain a picture of a handsaw. The experimenter asks him what he saw, and Joe says, “Hammer.” He is then asked to close his eyes and let his left hand (connected to his right brain) draw what he saw and he draws the handsaw! When Joe looks at the picture, he recognizes that its’ a drawing of a saw, but when he’s asked why he drew it, he has no idea. You can watch videos of Dr. Sperry's experiment on YouTube. They are stunning to watch.

Through many elegant experiments, Sperry’s team found that “Joe” actually lived in his left brain, and that the named self that we all identify with is inextricably tied to our ability to talk and name things.

When our hemispheres are surgically separated, our right brains demonstrate themselves to be highly intelligent and even better than our left brains at certain tasks, such as understanding emotional body language, facial expressions, and tones of voice. Their speech ability is quite limited though, and if their thoughts and feelings are going to be put into words, the information needs to be sent across the corpus callosum to the left-brain speech centers. Once there, it may be directly expressed, but it can also be altered, edited, suppressed, or even ignored.

Our ability to think rationally and to use speech and numbers has allowed us to build on our imaginative abilities and emerge as the most dominant creatures on earth. Perhaps because of this evolutionarily new and astounding power to alter our environment, the left brain has become a little over-impressed with itself. Because it alone has the ability to name things, it calls itself the dominant, or “major” hemisphere! That’s fair, because it can and does provide an override function in relation to the more emotional right brain, but it makes a serious mistake when it thinks that it is the only hemisphere that counts. While logical thinking is necessary for building skyscrapers and flying to the moon, it is nearly useless when it comes to creating and maintaining an emotionally intimate relationship, or responding to fast-developing threats.

The split-brain research showed us that we have another type of intelligence that coexists with our usual way of thinking about and describing our world. This intelligence has its own perspective, priorities, form of information processing, and motivations. It influences our daily lives much more than we know.

This intelligent “unconscious” mind undoubtedly lives in not only the right brain, but in other areas of both brain hemispheres and parts of the limbic brain that lack direct access to speech. It has eons of evolutionary experience that can guide us or help us solve problems. It tends to think in terms of how things are connected, rather than how they are different, and it excels in recognizing both spatial and social relationships. Bringing this emotional/intuitive intelligence into our problem-solving and emotional coping efforts greatly expands our ability to worry well; it lets us use all of our brain capacity to resolve rather than create worry and stress.

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