In two minds?

We have all heard the myth of being more right-brained or left-brained, with all your creative thoughts emanating from the left half of the brain and the cold, hard logical ideas materialising from the right. However, the human brain is much more complicated than that, don’t believe that 10% BS, we actually need a lot of it, ideally working together most of the time. Even if there is a great deal of plasticity to what each part of the brain is capable of doing, generally in a fully intact brain, there are specific regions that are dedicated to specific tasks. Working in tandem, the left brain sees and controls what your right-hand side is doing and vice versa, and most of the time there is no problem. Both halves of your brain complement each other. But what happens when they don’t?

Normally the two halves of your brain are connected via the corpus callosum, a bundle of connective nerve tissue which allows the two halves to communicate with each other. A corpus callosotomy is a medical procedure which severs this connection,  a pretty drastic operation which is sometimes performed on patients with particular aggressive forms of epilepsy. Stopping the spread of problematic electrical signals moving from one side of the brain to the other, and can reduce the severity of a fit when it occurs. However, severing this connection can have some unsettling side effects. It seems that when you cut your brain in twain (sorry couldn’t resist…half), you end up with two functioning and sometimes competing brains residing in a single body. Patients have reported that after their surgery they find their left-hand side moving and acting independently from what they intended it to do, and sometimes actively getting in the way of what “you” want to do, this phenomena is known as Alien hand syndrome(1).

 In fact, when scientists set up interviews with post-split patients and are asked a question, the interviewer might get different answers depending on which side of the brain is asked. It turns out there is a  “silent” partner in this relationship; as the speech and language centres of the brain are located in the left hemisphere, your body is only able to express the experience of this singular consciousness, with the left brain being able to speak to the rest of the world through speech, making attempts to rationalise the actions of their errant left hand, which is maybe just trying to communicate. In fact, these experiments showed that if you present information to only the left eye, scientists were able to pass messages to just the non-verbal right brain and get a response (through selecting from a series of multiple choice options) without the patient’s outward consciences even releasing! Original research into these dissociated consciousness was conducted by Sperry in 1968 (2), and although his observations were only on a small sample size of patients, with many other confounding factors and little ethical scope to expand on, or repeat these experiments, Sperry’s findings piqued researchers curiosity.  

These ideas raise a lot of deep questions, does the process of splitting a brain in half in fact create two separate consciousness within our heads or are we always juggling the will of two individual intelligence’s? Do we all have a silent passenger who is just on just along for the ride; a separate consciousness whose will is over-ridden by that half of a brain with a big mouth, which is able to explain their actions to the world with their fancy words. Or is life just that much more simple when you can share your thoughts with yourself, acting as a single entity after learning to share this one life?  What happens when we separate the one into two, when the right brain is finally given a taste of its own autonomy. Who are we anyway? It may seem obvious that ‘we’ would reside in the side of the brain which is able to vocalise our opinions, but just as the speech centre is isolated to one half of the brain, this can be said for many other important aspects of personality, although to what extent these functions are isolated to a specific brain hemisphere is still heavily debated. For example, Gazzaniga and Smylie conducted a 1983 study on split brained patients (3), exposing each half of the brain to a number of human faces, some of which the patient knew and should recognise, others who were complete strangers. Their research suggested that there is a stronger association with the right brain regarding and the ability to recognise someone else’s face.

So, who are you exactly? Your ability to speak to the world? or to recognise your friends and family? It seems that although a human can live in two minds, life runs a lot more smoothly when both sides work together.              


1.Ridley, B., Beltramone, M., Wirsich, J., Le Troter, A., Tramoni, E., Aubert, S., Achard, S., Ranjeva, J.P., Guye, M. and Felician, O., 2016. Alien hand, restless brain: Salience network and interhemispheric connectivity disruption parallel emergence and extinction of diagonistic dyspraxia. Frontiers in human neuroscience, 10, p.307.

2. Sperry, R.W., 1968. Hemisphere deconnection and unity in conscious awareness. American Psychologist, 23(10), p.723.

3. Gazzaniga, M.S. and Smylie, C.S., 1983. Facial recognition and brain asymmetries: Clues to underlying mechanisms. Annals of Neurology: Official Journal of the American Neurological Association and the Child Neurology Society, 13(5), pp.536-540.

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