SPLIT BRAIN EXPERIMENTS

Split-brain experiments were hugely scientific at first, but later developed into a philosophical discussion. The beginning of this theory, to be candid, is kind of “freakish”. In the mid 20th century, certain patients who were desperate to treat severe epilepsy and cease seizures underwent a procedure that severed the nerve fibers connecting the left and right cerebral hemispheres. Due to this procedure’s invasive nature, it is rarely used today.

To get a stronger understanding of this procedure, let’s delve into a basic overview of the brain. The brain has contralateral control, in which the left hemisphere controls the right side of the body and vice versa. The left hemisphere of the brain also focuses on language, logical reasoning, and analytical tasks. However, the right hemisphere controls visual imagery, holistic processing, facial recognition, and spatial abilities. The bundle of nerves we were talking about earlier–the ones that are severed during the procedure–are called the corpus allosum, and are in charge of transferring the information to the left and right hemisphere immediately.

As a result of this experiment, major scientific experiments were made, which led to the discoveries of philosophical discoveries as well. One discovery they found was that if an image was shown to the right visual field, the patient was able to verbally describe it, since everything on the right side is perceived by the left. However, when they showed something to the left visual field, the patient couldn’t verbalize anything but were able to draw the object or distinguish the object only with their left hands.

These scientific discoveries led to the creation of multiple philosophical theories. The main one is the dual consciousness hypothesis. This hypothesis is that each hemisphere has its own stream of consciousness and decision-making abilities. Essentially the idea that there are two minds in the brain.

There were some rare cases in which there was “intermanual conflict” between the brains. Specifically, one hand would try to do one thing while the other one tries to stop it. For example, one hand would button a shirt while the other one unbuttons the shirt. This, again, adds to the hypothesis that the two minds are their own entities.

The implications of this experiment are numerous. First, it was revealed that hemispheric specialization is incredibly nuanced; both hemispheres can do their own tasks, but sometimes the efficiency of the tasks differs. The implications also challenge the idea that we have one single self. Instead, we may have more than one, maybe even more than two selves.