Our brain, like many other parts of our anatomy, is made up of two halves, a left brain, and a right brain. They are connected by a thick cable of nerves at the base of each brain, called the corpus callosum. It is analogous to a cable or network connection between two incredibly fast and immensely powerful computers, each running a different program to process the same input.

When Roger Sperry severed the corpus callosum in the sixties, which connected the left and right brains, he was stunned by the fact that his ‘split-brain’ patients behaved as if they had two minds and two persons in one body! He found that the patient could name an object but could not explain what it was used for when the object was shown only to the right eye (the left ‘verbal’ brain processes data from the right visual field).

When shown to the left eye (the right ‘non-verbal’ brain processes data from the left visual field), the patient could explain and demonstrate its use, but could not name it. Roger Sperry received the 1981 Nobel Prize for his work in this area. It appears that when a normal person names an object and explains its purpose, both halves or hemispheres of the brain, which are connected by the corpus callosum, participate in this conclusion.

Split-brain vs. Normal People

Split-brain studies imply but do not prove that ordinary people have two minds. However, there is abundant scientific evidence that demonstrates the relevance of split-brain findings for ordinary people with intact brains. In split-brain patients, the left brain uses different strategies from the right brain. Scientists have found that ordinary people have the same differences in cognitive abilities between sides as split-brain patients.

If an ordinary person is seated in front of a screen and asked to look forward and an object is flashed very briefly to his right side (i.e. his left brain), he will respond faster and more accurately if the task involves language. If you flash a spatial task, for example, asking the subject to identify if a dot is within a circle, he will perform better when flashed on his left side (or to the right brain).

Ordinary people are also shown to be better at seeing the overall picture if an image is flashed to the right brain. These studies and others involving hearing through the left and right ears have been repeated many hundreds of times in ordinary people, and the findings are consistently similar to those in split-brain patients. The findings mean that the cognitive abilities of the left and right brains of split-brain patients are similar to those of ordinary people.

PET scans show that even when normal people (with intact brains) talk, the blood-flow pattern changes in their brains, and there’s more activity in the left brain than in the right. When they imagine space, the pattern reverses. One study on occupational preferences in cognitive styles showed that those who declared English as a major had a greater blood flow in the left brain (the verbal brain); whereas those who majored in architecture had a correspondingly higher level in the right brain.

Different modes of thinking

The term ‘left brain’ used in this book includes both the higher (i.e. the neocortex) and lower (for example, the amygdala) brain structures on the left side of the brain. Similarly, the ‘right brain’ includes both the higher and lower brain structures on the right side of the brain. According to Bernice McCarthy, the two brains control two different ‘modes’ of thinking or cognitive styles.

Each of us prefers one mode over the other. While the left brain is logical, sequential, rational, analytical, and looks at parts; the right brain activities appear random, intuitive, holistic, synthesizing, and looks at wholes. The left brain processes information from parts to the whole; the right brain, however, processes from the whole to the parts.

The right brain is holistic and uses top-down processing

According to Ornstein, from the early studies of the split brain through recent research on the whole competently functioning brain, the scientific understanding has become increasingly certain of the right brain’s role in seeing the large view. Seeing a large organization is a specialization of the right brain. More specifically, Newberg and d’ Aquili believe that the right parietal lobe is involved in a holistic (top-down) approach to things whereas the left parietal lobe is involved in a more reductionist and analytic (bottom-up) process.

Many split-brain studies confirm that the right brain is superior at assembling pieces of the world into a coherent picture. When we lack a higher-level perception, the world will seem like a disconnected maze of individual experiences; the brain does not assemble three individual lines into a triangle. We only see a ‘triangle’ when we change our viewpoint. To some extent, this evidences a ‘higher-dimensional’ view of the subject.

Whereas the left brain has a ‘linear perspective’ in that it sees three individual one-dimensional objects i.e. lines; the right brain, on the other hand, sees a whole two-dimensional object i.e. a triangle. The right side seems to be specialized for the large elements, the overall shapes of objects, and the word shape. The left side handles the small, precise links that carry the smaller, more precise meanings and movements.

It’s this specialization that contributes to one side is good for the analysis of small features versus the holistic vision of the other side. The left hemisphere is more focused on details and the right hemisphere is better at perceiving overall patterns. This also goes for language processing.

People with right hemisphere damage can always understand the literal meaning of a request, but they cannot always judge what the request means in context (in other words, the ‘other dimensions of the subject). The use of metaphor involves the right hemisphere. Metaphors, like indirect language, sarcasm, or irony, convey a significance that is different from the literal meaning.

Many right brain-damaged patients also seem to have difficulty in identifying the gist of passages. In order to do this, we need to be able to see things as a whole. This has also been alluded to in metaphysical literature. Charles Leadbeater says that the ‘causal’ [or higher dimensional] consciousness deals with the essence of a thing, while the ‘lower mind’ [associated with the left brain] studies its details.

Excerpted from the book Brains and Realities.

This excerpt has been edited and condensed for clarity.

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