An analysis of 150 cases of left-handers of pre-school and school-age who were subject to examinations and observations shows a rich symptomatology of changed left-handedness. The analysis is un derlaid with tables (numerical surveys), from which the following conclusions can be drawn:
1. Only 16 out of 150 left-handers remained unchanged and without any striking difficulties. All the other 134 left-handers who were trained to become right-handers developed all kinds of disorders. Among those who were changed three quarters were boys and only one quarter were girls.
2. The changing is done by various methods in the family before the children start to attend school, but it is mostly done at school, mally in the first year of the primary school, when they are forced to write with the right hand.
3. Among the disorders accom panying the forced change from left-handedness to right-handedness motorinstabillty is the most frequent (55.5 percent). The following disorders come next: changes In behaviour, difficulties In writing with the right hand, anxlosity and other kinds of neurosis, sttutterlng, difficulties at school, dyslexy, dysgraphy, and others.
4. While the average number of disorders is 2.8 per one child of pre-chool age, it Increases In the first year of school and keeps on increasing In the following years (the average being 5.2).
5. Incorrect habits of left-handed writing while left-handedness Is tolerated represent the most easily adjustable disorder. The adjustment of laterality removes the instability regulates the pupil’s behaviour and attitude to school, eliminates neuroses, and Improves the pupil’s work at school.
6. Return to original left-handedness brings the best results If attempted with children of pre-school age, in the first and even in the second year of school attendance. Later on the results are not so good, but success may be achieved even in the 8th year.
7. An experiment was made with 125 pupils, originally left-handers, to have them to return to the left hand. The experiment was almost with 53 per cent, successful, with 36 per cent, failed.
8.-9. Pupils who are forced ta write with the right hand while being allowed to draw with the left hand bear this dissociation of lateratily worse than those who are completely changed.
10. While the average of disorders among partly changed pupils Is 5.8 and among completely changed 4.6, It Is only 0.7 among those who were not changed at all, or, who were returned to left-handedness In time, 1. e. In pre-school age.
11.—14. Complete left-handednes, unlike crossed left-handedness [1. e. dissociation of motor and sensorial l,eft-handedness), strongly resists changing and reacts to forced changing by numerous disorders. Return to the original genotype Is more successful with complete left-handedness than with crossed forms.
In the same way left-handedness of a higher degree Is more resistant to changing, bears It worse, and more easily returns to the original left-handedness than left-handedness of a lower degree.
Educational practice must respect the pupil’s laterality, taking Into account the type and the degree of left-handedness. Encouraging complete left-handedness or left-handedness of a higher degree contributes to the prevention of disorders and to the success of education.