The so-called unity of consciousness is an illusion… we like to think that we are one but we are not.” — Carl Jung, 1935

Have you ever surprised yourself in a situation, demonstrating unusual bravery, intelligence, or poise, only to feel afterward that it wasn’t you who performed those actions but some other, more competent self ? Have you ever thought: “I can’t believe I did that”? Have you ever felt like you were having a conversation with two “yous” in your head?

In talking to friends, I have found that these experiences are relatively common. People report feeling mildly dissociated from themselves then and again, as though the person they call “I” is actually made up of multiple selves. These feelings usually pass quickly and are not excessively disturbing.

Multiple You’s

When the feelings are chronic and cause impairment, this dissociation becomes pathological. The most extreme versions of dissociation come in the form of dissociative disorders, the most popular being Dissociative Identity Disorder (formerly known as multiple personality disorder). Those living with dissociative identity disorder experience a divided consciousness. They have a primary personality in addition to multiple secondary personalities that regularly take over their minds. They often report having no memory of what they did while under the influence of these secondary personalities.

Although this is an extreme case of a split mind, I believe that even without mental illness there are different parts of ourselves we don’t have access to in our daily lives. Our “self” may not be a single, coherent entity.

Think about the idea of “finding yourself,” a trope in Western culture found in popular books and movies from Catcher in the Rye to Titanic. Discovering one’s true identity is a lifelong goal that is rewarding yet difficult to attain. What if this difficulty stems from the fact that our identity is not unitary, and is instead a function of many independently-willed brain regions interacting? This may why people report arguing with another “self” in their head or not recognizing themselves in certain situations. It may be why is often so hard for people to construct a single, coherent identity for themselves.

Examples from Science: The Split Brain Patients

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Experiments with “split brain” patients can be used to illustrate the competing wills within our minds. What does it mean to have a split brain? Well, normally, our two brain hemispheres, left and right, communicate via the corpus callosum — a thick band of connective tissue situated between the two halves of the brain. When this band of tissue is cut, communication problems ensue. People with a cut corpus callosum are commonly known as “split-brain patients” in the scientific community. Experiments with these patients illustrate how different parts of our brain may have their own agency — and possibly their own identity.

Some of the first “split brain” experiments were carried out by Roger Sperry, who won a Nobel prize for his work. In one experiment, he had patients attempt to solve a geometric puzzle with either the right or left hand. You can watch a video of this experiment on Youtube here. The participant had no trouble solving the puzzle with his left hand. Because the left hand is controlled by the right brain, which is responsible for recognizing spatial patterns, the left hand performed the puzzle task with ease. However, when the patient attempted to solve the puzzle with his right hand, he was stumped. Due his cut corpus callosum, his right hand could receive any direction from his expert puzzle-solver right brain. In the video, you can see that the left hand tries to help the struggling right hand. Yet, it seems right hand does not want help. The two hands fight against each other — a manifestation of the two halves of the patient’s brain fighting against themselves. Clearly, different brain regions have independent wills. And each region may be responsible for constructing part of our identity.

Another striking experiment comes from renowned psychologist Michael Gazzagnia. In this experiment, Gazzagnia showed split-brain patients a screen. On the side of the screen corresponding to the left visual field, a picture of a naked women was projected. The part of the screen corresponding to the right visual field was left blank. When the image of the naked woman was projected, the patient chuckled. But when asked to articulate what they saw, they could not name the source of the amusement. Why was this so?

The left visual field projects to the right hemisphere of brain, while the right visual field maps onto the left. Because the picture of the naked woman was positioned in the left visual field, it was only really “seen” by the right hemisphere. However, the right hemisphere cannot produce speech–that responsibility falls to the left hemisphere. Thus, since the speech producing left-hemisphere had no access to the photo, the patient could not articulate what was seen. However, their right brain still registered the image, which is why they chuckled.

This interesting experiment illustrates that the two hemispheres of our brain act independently of each other. Because the corpus callosum was cut, the two brain hemispheres could not communicate. The right brain found the photo funny, and the left brain didn’t understand why.

Split brain experiments show that a split brain results in a split mind. Consciousness is not unitary, but rather a function of multiple brain regions.

The case of Karen Byrne is a more recent example of a split brain patient’s divided mind. Karen Byrne’s corpus callosum was cut as a cure for her epilepsy. However, after the surgery, noticed something very strange. Her left hand seemed to have a mind of its own. It would slap her black and blue whenever she smoked or cursed. It would take of her clothes without warning. She noted that hand’s actions were not sporadic reflexes, but instead seemed to be carried out with intent.

Her doctors told her she had something called Alien Hand Syndrome. This condition occurs when hierarchy of communication between brain regions goes awry. Usually, the more analytical left hemisphere of the brain is dominant, having the last say in our actions. However, when the corpus callosum cut, the left brain no longer dominates over the right. The left hand, controlled by the right brain, can act independently.

Karen began to notice a pattern to the hand’s abuse. Her hand hit her whenever she deviated from the moral teachings she grew up with. She was taught that smoking and cursing were wrong, so her hand tried to stop her from doing these things. This principled, pious part of herself was always there, but now manifested in her alien hand. Thus, Karen always had this other identity within her. But now, because of her split brain surgery, the identity was clearly shown.

So who are we?

I am fascinated by the idea that multiple identities may coexist in my own brain — that the person I call “me” is actually a collection of independent agents. The thought is profound (but also extremely unsettling).

I think all people cling to the idea of a single, unique self. It is uncomfortable to think otherwise — then who would we be? How would we define ourselves?

The thought of “me” as being completely whole and unified is comforting. But, maybe it isn’t quite true. Maybe it’s just a story I tell myself to make sense of the way I experience the world.

Written by

Documenting insights about humanity, culture, and design. // Self-experimenter, UX Designer @ Google.

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