Mindmelding: two brains, one consciousness?
By William Hirstein
Have you ever wondered if it is really possible for others to know what you are thinking? Our brains seem to allow both “internal” points of view, and “external” ones. As individuals, we know them from the inside as we experience our thoughts, perceptions, and emotions. Scientists, on the other hand, only know our brains from the outside, as they employ brain imaging, EEG, or other types of techniques. This appears to imply that scientists are cut off from ever studying our brains from the internal point of view. But if this is right, it has huge consequences for the way we think of our minds. If our thoughts and feelings exist in a realm that science can never touch, then perhaps they aren’t really physical? And if this is right, it would lend great support to the ancient theory of dualism, according to which the mind and the brain (along with the rest of the body) belong to two different metaphysical categories, the mental and the physical.
However, the apparent wall between our minds can be broken down. I believe it is possible to connect two brains in such a way that their owners share a single conscious state that I call mindmelding. The possibility of mindmelding also forces several interesting changes in the way we conceive of our sense of self, in how our brains represent the world, and in how we speak about the minds of others.
A fascinating recent discovery may shed light on these issues. Krista and Tatiana Hogan are 4-year-old twins who were born conjoined at the head. Images of their brains reveal a bundle of fibers connecting their thalami, an organ at the center of the brain vital for perception and consciousness. Controlled studies are now underway to test the hypothesis that they have “internal” access to each other’s minds, but there are some tantalizing clues that they do. One sister will laugh at a television program only the other can see (their heads are joined in such a way that their fields of view are angled away from each other). Scientists who have examined them believe that sensory information entering through one girl’s eyes is actually split and sent to visual areas in both of their brains.
But, if this is correct, they are not experiencing the same conscious perceptions, because the split has occurred early enough in processing to result in two separate conscious states that are very similar to one another. Thus this provides room for doubt as to whether they are really experiencing each other’s conscious states, as opposed to copies of them, since one can doubt the fidelity of the copy. What if we made the split later in processing, however, so that there was only one conscious percept, which the twins might react to differently? Then they would be experiencing the same conscious perceptual state, even if they react differently to it. If this could happen, the consequences for the age-old debate about the nature of our minds will be huge.
If mindmelding is possible, however, it represents the most severe violation of our natural mental privacy in the history of mankind. I would recommend that mindmelding be thought of as a medical technique, used solely to gain information about mental illnesses, and used only with the consent of the subject. Yet it is clear that the pursuit of mindmelding will bring with it a pointed and increasingly urgent ethical discussion of the place of such techniques in our society.
William Hirstein is Professor and Chair of the Philosophy Department at Elmhurst College, in Elmhurst, Illinois, USA. His book, Mindmelding: Consciousness, Neuroscience, and the Mind’s Privacy, published this year.