I don’t recall who should take the credit for the famous joke about the sciences being divided into the natural and the unnatural. In the first category we find, of course, such respected disciplines as physics and chemistry, with biology hanging in there as a poor, but respectable relation. True, following the discoveries made in genetics, the development of genetic engineering and molecular biology, the status of biology has risen. The second category is home to the humanities, while psychology and psychophysiology (the science of the working of the brain) occupy an indeterminate place somewhere in between: as experimental sciences they have moved beyond the other humanities, but have yet to reach the level of the natural sciences. And in truth, can we name a discovery in the science of the brain comparable in significance with splitting the atom in physics?
It happens that we can. By a strange coincidence, it also involves splitting, though not the atom but the brain. However, let us begin at the beginning.
In the mid fifties of the last century a number of American researchers and doctors had an idea for an unusual treatment in hopeless cases of epilepsy. They had in mind cases involving frequent, serious epileptic seizures with loss of consciousness and convulsions, which did not respond to medication and quickly resulted in almost total invalidity. The principle behind these convulsions lies in a kind of vicious circle: pathological (epileptic) electrical activity that begins in one hemisphere of the brain spreads to the second hemisphere via the multitude of nerves which link the hemispheres. Now, when such an epileptic ‘fire’ takes hold in the second hemisphere, it fuels and strengthens the original outbreak in the first hemisphere through those connections, and so they keep feeding each other until the epileptic seizure exhausts all the brain’s electrical energy for a while. And then everything begins all over again, with every seizure easing the path for subsequent attacks.
The Americans had a simple idea: divide the right and left hemispheres of the brain, sever the nerve connections between them, so as to prevent the systematic distribution of epileptic charges throughout the brain. The hemispheres are connected by millions of nerve fibres which pass information from one hemisphere to the other and form the corpus callosum or calloused body, a dense whitish mass, which forms a kind of bridge between the hemispheres. This operation was performed on a number of patients, and did provide real relief from their problem. At the same time, it led to a major discovery, resulting in a Nobel Prize for Professor Robert Sperry in 1980.
But what happened after the severing of the corpus callosum to a person’s behaviour and psyche? At first glance, nothing special, and this was quite surprising in itself. The connections between the two halves of the brain were destroyed, but the person ate, carried out everyday functions, walked and talked with other people without serious irregularities in behaviour. Some patients did report unusual happenings soon after the operation. One complained that he was behaving strangely with his wife and was not able to control his actions: he would embrace his wife with his right arm, but meanwhile his left arm was pushing her away. Another patient noticed his left arm acted strangely before a visit to the doctor: he used his right hand to do up his buttons and adjust his clothing, while his left hand was busy undoing the buttons and trying to take his clothes off again. It was exactly like in the the old saying about the left hand not knowing what the right hand was doing. In fact, it wasn’t so much the hands, as one hemisphere of the brain not knowing what the other was up to. The right hand is controlled by the left hemisphere, and the left hand by the right. However, in the early stages of the research not enough attention was paid to this detail.
When basic observation of the behaviour of patients who had undergone the operation gave way to systematic study of their mental functions, researchers were astonished. Many activities which present absolutely no difficulty to a person with an intact corpus callosum proved impossible for patients whose connections had been severed. The right hand, on which the majority of us rely in most situations, was unable to carry out the simplest tasks: it could not draw elementary geometric shapes, construct objects out of blocks, or find everyday objects by feel. The left hand coped well with all these tasks, but could not write a single word, even in the most spidery of handwriting. As it happens, right-handed people can’t usually write with their left hand even with the corpus callosum intact.
So, the right hemisphere, which controls the left hand, did better than the left hemisphere in all tasks, with the exception of writing. But at the same time, in addition to writing, the right hemisphere also had no control over the function of speech. True, the right hemisphere was capable of understanding speech, as long as the grammatical constructions were kept simple. But producing speech was beyond it. Doctors had known for a long time that damage to the left hemisphere impairs speech, even if the right hemisphere remains intact. Yet the right hemisphere was significantly stronger than the left in spatial orientation, perception of music, and interpretation of complex images which cannot be broken down into simple component parts, in particular recognition of human faces and expressions. Understanding metaphors and appreciation of humour were also connected with the right hemisphere.
Very interesting food for thought has come out of experiments in which left and right hemispheres were in turn temporarily ‘switched off’, without severing the corpus callosum. The switching off took place by means of electric shocks administered to patients suffering from mental illness. Professor Vadim Deglin of St Petersburg would pose patients while undergoing this treatment a simple problem of logic like – “All monkeys can climb trees. A porcupine is a monkey. Can porcupines climb trees?” When the patient recovered sufficiently from the ECT to be able to answer questions (though one of the hemispheres still remained much more suppressed than the other), those whose left hemisphere had been shut down answered in the negative, while those whose right hemisphere had been switched off gave a positive answer. This does not mean that people with a shut down right hemisphere and a functioning left really can imagine a porcupine climbing a tree. When asked directly whether a porcupine could, they answered ‘no’. But they followed the formal logic of the problem blindly and without deviation, without thinking about the reality of the situation: they had been told a porcupine was a monkey, monkeys climb trees, therefore porcupines must climb trees, too.
Research into this problem was further advanced in some interesting experiments carried out by Professor Julius Kuhl’s group at the University of Osnabrück. Their work showed that following simple physiological activation of the left hemisphere (through physical exercises with the right hand) healthy people accepted decisions imposed on them by outside authorities as their own. What was happening was the ‘infiltration’, as it were, of imposed decisions into the consciousness.
It clearly follows from this experiment that the left hemisphere is much more oriented towards logical constructions than actual, living reality. But as a result of this orientation, the left hemisphere is more targeted than the right towards defining unambiguous norms and relationships of cause and effect, which is necessary in scientific thinking. An ability to solve formal syllogisms, along with the development of left-hemisphere activity in general, is fostered in the process of school education. In little children, along with peoples of other civilizations who are not exposed to our education system, it is the right hemisphere that dominates, with its orientation towards the real world which pays little heed to the laws of formal logic.
The brain is constructed in such a way that if visual information comes in from the left (left field of vision) it goes to the right hemisphere, while if it comes in from the right (right field of vision), it goes to the left hemisphere. Naturally, if the two hemispheres have not been separated it doesn’t matter which hemisphere the information goes to. It is instantly, in a fraction of a second, transferred across the corpus callosum to the opposite hemisphere. But what happens in the case of a severed corpus callosum? If the information passes to the left hemisphere, it is realised and the person has no difficulty in expressing his attitude towards it in words or actions. If it passes to the right hemisphere, then the person’s behavioural reaction to it may be appropriate, but he cannot explain the reasons for his behaviour, nor can he say anything about the information itself. In other words, he does not realise it. In one experiment a female subject was shown a number of slides with pretty landscapes in her left field of vision. Suddenly a hard core pornographic picture flashed up and the subject giggled with embarrassment. When asked why she was laughing, the subject at first found it impossible to answer and then said: “You’ve got some funny looking machines here”.
This experiment is a good demonstration of some very important basic principles of the way the human psyche is organised. Information a person is not aware of may initiate actions without him knowing the true reasons for them. This has been well known in psychology since the time of Freud. But people cannot bear not being able to explain the reasons for their behaviour. So they will always find a pseudo-explanation, allowing them to remain in a state of blessed certainty that they are consciously and purposefully in control of their own actions. This mechanism is also clearly to be seen in the phenomenon of psychological defence, which we described in chapter one.
Not long ago American researchers carried out some more sophisticated experiments, which show compellingly that the exchange of information between right and left hemispheres is not identical, and that the right hemisphere possesses certain advantages. A subject with a divided brain was shown two two-digit numbers, one in the left field of vision and the other in the right. He was asked to add them together and indicate whether the result was an odd or an even number. The answer was not to be given verbally, but by pressing one of two buttons. In most cases the answer was right, in other words the behaviour – pressing a button – met the conditions of the task. However, the subject could only name the number that had been presented to the left hemisphere (right field of vision). Since everything that is presented to the left hemisphere can be articulated verbally, we must assume that the left hemisphere did not possess the information about the second number.
But the right answer had been given, and it would be logical to conclude that the final decision had been made by the right hemisphere. But for this to happen the right hemisphere would have had to have all the information. We have to suppose that if information is transferred from the right hemisphere to the left by the nerve pathways that make up the corpus callosum, then information must pass in the opposite direction (from left to right) by some additional means. From a purely anatomical point of view, this is possible. Both hemispheres are seated, as it were, on the brainstem – a very important asymmetric formation which contains all the vital centres. Communication between the hemispheres could in principle pass through the brainstem. For a long time it was thought that all meaningful information is transmitted only via the corpus callosum, but the experiment I described above makes one suppose that the right hemisphere is in a privileged position. It receives information from the left hemisphere additionally via channels on the brainstem. The experiments were repeated using two syllables (the subject had to decide whether they made up a word or a meaningless jumble of letters) and two lines (were the lines parallel or perpendicular to each other). The subjects gave the right answer in all cases, though they could only account for information presented to the left hemisphere.
The idea that the right hemisphere enjoys an advantage in receiving information is supported by certain other very interesting data. Research has shown that the right hemisphere of healthy people ‘grabs’ all information a fraction faster than the left. It is the right hemisphere that gathers in information from all around, from both left and right. The right hemisphere is quicker and more successful than the left in interpreting complex, ambiguous information (such as expressions on the human face).
There is one final argument, though because the data was not obtained under strict experimental conditions, it does not yet have the strength of scientific proof. If a person finds himself in a situation needing quick decisions and instant action that match up to the difficulty and complexity of his predicament, he often takes all the necessary steps before developing a real understanding and analysis of events. Then, once he has done everything, he is unable to list what he has done and the order in which he did it. His behaviour was unconscious, but happened to take all key aspects of the situation into account.
Something similar happens in hypnosis. When a subject is given the suggestion that he is in a forest glade with lots of ripe wild strawberries, he acts out the suggested situation of picking strawberries. He is not aware that in reality he is in a city apartment with all the usual furniture. Nevertheless, he successfully avoids tables and chairs, doesn’t bump into cupboards and walls, and after returning to a normal state of consciousness can say nothing about what happened under hypnosis. From an outside observer’s point of view, his behaviour was strange but, all the same, purposeful, well-organised and took into account all the various obstacles. There are grounds to suppose that such integrated behaviour without the intervention of the conscious mind, both in hypnosis and in extreme situations, is controlled by the right hemisphere. I provided a detailed account of this point of view in an article I wrote jointly with Vladimir Raykov more than 30 years ago. Since then a great deal of experimental work has been done which convincingly demonstrates the dominant role of the right hemisphere during hypnosis. This function of the right hemisphere is inseparable from its ability to seize quickly all available information and evaluate its significance before it is fully realised.
This property of the right hemisphere helps solve an old psychological paradox. In the chapter on psychological defences we wrote that these mechanisms protect the consciousness from unacceptable information. However, at the same time as they protect the consciousness, these mechanisms themselves function without the participation of the consciousness. Where does the knowledge come from about what particular information should not be allowed through to the consciousness if the consciousness does not intervene directly in the work of the psychological defence mechanisms and is not even given any information about this work?
I suggested that the right hemisphere is the place where we see the formation of the self-image – the image a person has of his whole self, the means by which he preserves his self-identity, his association of his image with his self. The self-image cannot be formed without the participation of the consciousness, the consciousness which is responsible for all his waking actions and principles, for his social motives. On the other hand, the self-image is a full-blooded image, having innumerable connections linking the person with other people and the world in general. This image is so complex, has so many different facets and meanings, and, not infrequently, a capacity for internal contradictions, that it cannot be realised in its entirety as a whole. Our logic-based consciousness usually ‘straightens out’ and simplifies reality and is incapable of grasping the sheer quantity of connections that characterise the self image. No matter how much information a person provides about himself, he never feels that he has given a full account or analysis. He always has a sense that he is immeasurably richer than his own perceived idea of himself. This feeling is based on the self-image.
You might say that the self-image is the plenipotentiary of the consciousness in the realm of the unconscious (right hemisphere). And because the right hemisphere ‘grabs’ information a little quicker than the left, the self-image has an opportunity to evaluate this information before it is realised and decide whether to allow it through into consciousness. And as the fully empowered representative of the consciousness, the self-image has the authority to take such a decision and, consequently, is the basic regulator of our behaviour.
But we have yet to answer the question about what, in fact, is the basic difference between the hemispheres, what their purpose is in a system of thinking, which would be able to explain all the myriad facts within a single system. This question has generated a lot of discussion in the scientific world, and we shall try to answer it in the next chapter.