Individuals in our society have always been thought of as just that, individuals. We are individuals with our own opinions and desires. As individuals, we are distinct, consciously aware beings. But what happens when it is suggested that there may be more than one individual within each of us? In the second half of the 20th century great interest was shown in the physiological phenomenon known as the ‘split-brain’, a procedure involving the severing of the higher connections between the two cerebral hemispheres for the treatment of epilepsy.

This resulted, according to some, with each cerebral hemisphere experiencing its own perceptions and sensations, while others claim the findings can be explained with reference to a single person. The ways in which the two cerebral hemispheres interact result in the concept of a person as we know it. When the hemispheres are separated, their interaction is impaired. They retain many integrated aspects of the system however they also experience a significant absence of communication.

This does not decrease the unity of the patient’s person, nor does it provide corroborating evidence for supporters of the ‘two persons interpretation’. 1 Roger Sperry (1968), the man largely responsible for most of the testing in both animals and people, concluded that the results confirmed the presence two mutually exclusive entities within each individual. The experiments conducted by Sperry (1968) allowed for the testing of each cerebral hemisphere and the respective sides of the body that they controlled, responding to a range of stimuli, including visual, auditory and other input.

The results indicated that each side of the body would only respond to stimuli flashed into its own field of vision. Sperry (1968), Roland Puccetti (1973) and Susan Leigh Anderson (1976) choose to explain these results with reference to two separate realms of consciousness, and Puccetti (1973) goes as far as asserting that all people have two ‘selves’ within. However, the findings can be explained much more clearly and simply by not questioning the unity of the individual. The hemispheres remain highly integrated – they control the same body and they are subject to the same experiences.

The results are evidence of one mind at work, but one that has two hemispheres having trouble communicating, yet they are still working to the same ultimate goal: helping the person to function as a human being. Consider a sport team, whose overall goal would be to win a game by scoring goals, say. A properly functioning team would communicate in various ways to facilitate the objective of winning a match. If the members of this team however, suddenly lost all methods of communication, they would not suddenly become several different teams.

They would still be striving toward the same goal, albeit in a much more inefficient, ineffective way. The same can be said for commissurotomy patients. Bogen (1969, as cited in Puccetti, 1973), studied 185 cases involving gross ablations or even complete hemispherectomy. The reports suggest that essentially the same personality, character traits and long term memory traces persist postoperatively. Whereas Puccetti (1973) sees no other way to explain this than the surviving person was in actual fact the surviving one of two very similar persons. Again, it is much more easily explained by taking the mind as a unit.

It has the right and left cerebral hemispheres that specialise in their respective ways, the left hemisphere largely responsible for language while the right is very adept at copying figures and pictures. They both contribute equally to the personality of a person, it is a concept above the functions of two specific areas of the brain. When one of these hemispheres is removed, as in Bogen’s study (1969), the results showed conclusive evidence that the patients’ personalities remained intact, while the service of whichever hemisphere was removed was absent from the patient.

This leads to an interpretation not of two minds, but one that has lost an important function. Without one’s left hemisphere, one has trouble speaking, and without a leg, one has trouble walking. These are both functional difficulties that do not take away from one’s personality. Moor (1982) describes a rather entertaining ‘science fiction patient’. This is a patient whose cerebral hemispheres conflict in a wide range of emotions and desires. They respond to different names, prepare different food and listen to different music.

This would be the result of a true split brain, two realms of consciousness within the one person. If the hemispheres were each intentionally autonomous spheres of consciousness, the system of the human body would go haywire; the eyes would focus on different things, the ears would tune into different sounds. There would be no centralised authority of what stimuli are focused on which we see in commissurotomy patients the majority of the time. These patients are capable of perceiving two things at once, but this is only noticed under the close control of experiment.

There are only a small number of cases where real conflict between the hemispheres of commissurotomy patients was evident. Zaidel (1972, as cited in Puccetti, 1973), reports a patient shortly after the operation pushing a plate away with one hand and retrieving it with the other, only to have it pushed away again. Puccetti (1973) cautions that these more extreme cases are only evident in the early postoperative period, and are also the result of brain damage in the patients.

Still, there is an obvious conflict of desires here, but as Baillie (1991) explains, this conflict is present in all of us, without our unity of mind being called into question. The only difference in this patient was the strange way that these desires manifested. While perception is segregated in the split-brain cases, the bottom line is that commissurotomy patients function as normal people outside of the experiment setting, with a centralised consciousness. A personality consists of more than a response to simple stimuli.

Rather, it is a complex organisation of emotions, and a frame through which a mind operates. There is an absence of extreme cases like our aforementioned science fiction patient, and while there are some grounds for arguing that there are two spheres of consciousness coexisting in each patient, this contention remains problematic in the face of the more flexible and satisfying explanation that the cerebral hemispheres are only specific agents that provide a service for the human body, to which communication is vital, but not necessary for the unity of being.