Development of manual dominance

Often, many parents wonder at what stage or time of development children become clear Manual dominance , so that in Some cases often show a marked preference for the use of one of their hands to point or take toys while in many other cases This is quite variable.

The maturation of the different brain structures and the development of the motor functions will be essential for the establishment of the preference manual.

Types of manual dominance

• Right hand dominance (Right-handed): the right hand is used more preferably and more efficiently for writing and execution Of other motor acts.
• Left hand dominance (Lefties): the left hand is used more preferably and more efficiently for writing and Execution of other motor acts.
• Bilateral dominance (Ambidextrous) both hands are used indistinctly with the same degree of precision.

Prevalences

In the world population, right-handers account for between 85-90% of the total, while left-handed people make up 10% -13%. In many cases dominance Manual is not absolute, so there are at least 1% of ambidextrous people.

What to hedge?

Although there is a wide variety of explanatory theories, the body of Laterality and cerebral asymmetry he has Consistently demonstrated that there is a certain differentiated hemispheric specialization for the processing of information and that this Fact is an indicator of brain maturation.

Thus, the right hemisphere Appears to be biased toward emotional, attentional, visual-spatial processing and control of the part Contralateral of the body (left).

On the other hand, the left hemisphere Seems to be dominant for language skills and control of the contralateral part of the Body (right), in particular the control of the dominant hand.

In this sense, right-handers would present a left hemispheric representation of language and control of the dominant hand, so it would be expected That in the case of lefties this representation will be inverted in the right hemisphere.

However, the use of different Such as the use of the Wada Test or the RMF, have revealed that approximately 15% of left-handed individuals Right linguistic representation. Lefties are often considered to be more likely to recover from language disorders, Greater probability of presenting a bilateral hemispheric language organization.

At what time is it identifiable?

In relation to the development of cerebral laterality and consequently of manual dominance, different explanatory theories have been proposed.

The The first debates proposed the progressive development of hemispheric specialization and the existence of functional equipotentiality at the time Of birth. However, others propose the presence of asymmetry from birth.

Studies on dichotic listening in 18-month-old children revealed Which had greater evoked potentials in the left hemisphere in the presence of verbal stimuli and greater potentials evoked in the right hemisphere To auditory potential .

On the other hand, it has also been described the preferential turn of the head towards the right of babies of Right-handed parents the right hand preference in children who will be distros from 18 months.

From very early stages can be identified different patterns of manual preference, from the form of the sucking of the finger of fetuses during stage Of gestation, to postural asymmetries around 2 or 3 months. Being between the 3 and 6 more evident the manual preference for the management of objects.

The exclusive use or very marked preference for one hand in babies in less than one year may make us suspect of the existence of a Developmental disorder such as hemispheric cerebral compromise, ipsilateral to the preferred hand. However, when this use fluctuates During the first years of life we ​​would interpret it as the normal pattern of development.

In general, it is expected that the children will alternate the use of their hands for the performance of motors acts indistinctly. It is not until 4 Years of age, when manual dominance is defined.

conclusion

The establishment of manual dominance is an important milestone in child development, as it will have important implications for both development Of other motor skills as in the acquisition of curricular competences in the school stage. On the other hand, the evaluation of the acquisition Early or late dominance of manual dominance could be used as an indicator of deviations or problems in child development.