AMBIDEXTERITY.

Press, Volume L, Issue 14971, 19 May 1914, Page 5

AMBIDEXTERITY.

CAN BRAIN POWER. BE DOUBLED?

Can wo double brain power by teaching our children to write with both right and left hands? RIGHT AND LEFT BRAINS. "The Technical World" tells the story of a business man who wished to learn, Spanish, but his business cares were so great that he found he could not do so. A medical friend advised him to learti it by writing, the Spanish words with his left hand, the reason for this advice .being that the normal speech area has been located in tho left hemisphere of the brain. Why is this so? Sir W. R. Cowers says:—"The relation of the processes for language to the left side, of the brain is unquestionably connected with right handedness, siiiee persons who are left-handed present the «ame defects of speech in disease of the right hemisphere of the brain, as right-hand-ed persons do in the disease of tho left. They aro right-brained. A related fact is also important for those concerned in education. In children the destruction of the left motor speech centre never causes lasting loss of speech, as it does in adults. Tho exclusive relation of voluntary speech to the left brain is duo to the disuse for speech of the right brain." DORMANT MENTALITY. Dr. H. W. Donaldson, writing on the "Growth of tho Brain," makes a further statement to the effect that while injury to one hemisphere may be compensated in childhood by development of the other, such is not the

I case with adults. Against this* view jwe have the fact that Professor Fraenkel of Germany cured a right-handed patient of loss of speech by teaching; him to write with his left hand ! These statements show 'that -there is part of tho brain which is, in ordinary circumstances, unused. If this can be developed it is quite possible that brain power could he doubled. The suuporters of ambidexterity claim that both parts of the brain may he developed by the use of both hands in writing, drawing and other manual occupation:?. If right-handedness rests on other ground", than custom this may not be'practicable. Mr J. P. Jackson, an English authority on ambidexterity, claims thattho left hand is as capable of development us the right, or almost so. He claims that of every hundred children seventeen are naturally rightbanded, three are naturailv left-hand-ed and the balance of eighty are neutral. Exclusive right-handedness according to these figures, is a hardship to three per cent., while exclusive leit-handed-ness would be : , hard.-hii> to seventeen per cent. This may explain why righthai.dediie.ss is so generally adopted, but. that is no reason why the traing of the right hand should mean the neglect of the left. Many rea.sons are advanced to explain why we are righthanded. f HEREDITY AS INFLUENCE. The figures (|uoted above would indicate that right or left-handodness may be the result of heredity. Cases cited by authorities still further show that heredity may have a share. Most people can call to mind one or more cases in which a child has a marked inclination to use the left hand. In some cases a whole family is naturally left-handed ; in others only ono or two members are singular in this respect. Dr. Boyd, of St. Magdalene's Hospital. London, found that the leit hemisphere of the brain was on an average one-eighth oi" an ounce heavier than the right, hemisphere. Is this a cause or an effect of right-handedness?

Some medical men attempt a more subtle explanation of the preferential use of the right or left hand. They point out that with the exception of the organs in the thoracic and abdominal cavities, the lnxly may be divided into two halves, each part in ono half being represented by a similar part in the other half, but the lungs have two lobes in one side of the body and three in the-other. The heart lias no corresponding part in the right side. Tho stomach is found on one side, and the liver on the opposite side. Again tho weight of the stomach varies according to whether it is full or not. They say that even with the stomach full tho right side outweighs tho left by 15 ounces. Therefore, righthandcdness results from tho additional weight of the viscera on that side. This supposition would . require that lefthanded persons should have transposed viscera. The opponents of this theory say that this is not the case. The popular idea that mankind became right-handed because the use of the right hand in war caused the heart to be less exposed, is discounted by tho fact that the men spent only a small part of their time at war, and the women did not go to war at all. FACULTIES MAY BE CRIPPLED. Then we have left environment and education, both the result of custom. Before ever the child reaches tho schoolmaster he has either become right-handed or his natural Itefthandedness has been suppressed as much as possible by his parents or guardians. This, say the supporters of ambidexterity, is a wrong to the child. Mr Jackson says our national education is little better than a crippling of the child's . faculties and a serious diminution of the - national efficiency. Mr Jackson and his friends claim that by means of ambidextral- training loss of speech may in many cases bo prevented, that there will be few cases of writer's cramp, that craftsmen will become more efficient, that moral power wil] be perceptibly increased that brain speech area will be doubled, and that school work will become easier and the school course shorter. AUTO-SUGGESTION VALUABLE. It may be of interest to boy scouts to know thatitheir Chief Scout, Sir It. Baden-Powell, believes that the boy should bo trained in the use of both hands. Ho says:—"l have long been accustomed to write with both hands, and to use the two hands interchangeably. It is hardly possible to lay too much stress upon this bi-manual training." There is reasonable ground for tho belief that ambidexterity is within the reach of all ; tho next point to consider is will it prove tho means of bringing the unused part or parts of the brain into use?

Dr. Macnaughton-Jonos claims that manipulative exercises are intimately associated with the higher mental processes, and Dr.- Sequin considers the tactile functions as the most important of our senses. Madame Montessori's method of treating defective children is largely based on the researches of the latter, and it may. easily be that tho association between tactile sensations and mental processes is as much the cause of its success as the idea of autosuggestion.

Further, language is ft very important factor in thought. The "mind of a deaf and dumb boy or girl is almost a blank until the child has learned a vocabulary. Writing is an important means by which thoughts may be expressed and recorded. The exercise of writing any thought requires co-ordi-nation of brain and muscle. Every movement of the right arm is directly associated with the left hemisphere of the brain, and every movement of the left arm is directly associated with the right hemisphere. In tho right-handed individual the centre of speech is in the left hemisphere, and in tho lefthanded individual it is in the right. .From that it is claimed that the equal use of both hands will cause the development of both speech areas, and thereby double the brain power.