The brain is divided into two halves; the left and the right. The left side of the brain generally controls the right side of the body and vice versa. The two hemispheres do have similarities, but they also have many marked differences.
It has been discerned that the left side is the more technical, the more linear side of the brain. Its main functions are in speech and writing, along with balance and the organisation of movement. The right side is more holistic, more concerned with the emotional and visual aspect of things.
The left side of the brain is concerned with the expression of language and its comprehension, while the right side deals with different aspects of language. Prosody – the variation in the tone of the voice – is integrated on the right hand side. This also seems to be the location for the area which deals with ’emotionally potent language’ – or in other words, swearing.
The left side of the brain concerns itself with verbal memorisation. The recognition of words comes from this area. In addition, so does the short term memory of word sequences, or the ‘articulatory loop’. For instance, you can remember the short phrase, ‘I am a fish’ so long as you keep repeating it. If you stop repeating it, and do something else, then you will quickly forget the phrase.
As far as memory is concerned the right side of the brain does something similar to the left side, only with a more visual aspect. It is involved with the recognition of faces and your spatial location. It has a type of articulatory loop called the ‘visuo-spatial sketchpad’. For instance, look at the four corners of your computer monitor in this order; top right, bottom left, bottom right and top left. As long as you keep repeating that sequence, you will remember it. As with the articulatory loop, as soon as you stop and do something else, you will forget it.
The left side of the brain is primarily concerned with linear problems like arithmetic with the right side concerning itself with mathematics which has a spatial component like geometry or algebra.
Both the left and right side are concerned with ‘constructional praxia’, or the coordination of movement. However, the left side deals more with the ordering and programming of movements like writing, or making a cup of tea. The right side is more visual and spatial, for example, building something out of bricks. The right side also has an additional feature, and that is what is known as ‘dressing praxia’, or the coordination of putting your clothes on.
One of the most marked differences between the two halves is the emotional response. Whereas previous features have resulted in similar functions for different aspects of understanding the world around you, this is where the two halves become diametrically opposite. The left side of the brain is the optimistic half. It is associated with positive emotions like happiness, joy, pleasure, and general ebullience. It is also associated with the control of emotions. The right side is the pessimistic half. This is associated with negative emotions, such as anger, sorrow and generally being moody and bad-tempered. Whereas the left side deals with emotional control, the right side deals with emotional perception ie, the ability to read the emotions of others. It is also associated with the expression of emotion.
It is important to understand how the brain is organised as it can influence, for instance, the processing of what we hear. The primary centre for understanding speech for the great majority of people is located in the left side of the brain. Signals from our right ear go mainly to the left side of the brain and vice versa. Someone who has left ear dominance and thus listens mainly with their left ear, will receive conversation through their left ear, the signal of which will be sent to the right side of the brain. The right side will then determine that this signal needs to be processed in the left side of the brain and thus send it to the other side. Conversely conversation received through the right ear will go straight to the correct side of the brain – the left side. The additional re-routing required when listening with the left ear takes time and can lead to delays in understanding and speech impediments, such as stuttering.
By retraining how the brain processes sensory information it is possible to instigate significant changes in ability, behaviour and performance.
Efficient and smooth communication between the two brain halves is essential for full development. Children up to the age of about three have not yet fully established an effective cooperation between the two brain halves and this can be seen by how they make pictures or paint. They will use their right hand for the right side of the picture and their left hand for the left side of the picture, or alternatively move themselves physically over to the left side to position the left side of the picture to be in front of their right hand. They find it difficult to cross the so-called ‘midline’ and use their right hand on the left side of their body or vice versa. Special neuro-developmental exercises and activities can help to strengthen the cooperation between the two brain halves.