Laterality and cross laterality: what are they?

Why does each person have a preference when it comes to using a part of his or her body?

The body of the human being, like that of almost all the bodies that populate the whole of animal life forms, follows some patterns of symmetry. 

We have two arms, two legs, two eyes and a nose in our central axis, and the same logic is repeated in the arrangement of almost all our organs. We are adapted to perceive and act in a very similar way both to the left and to the right.

What are laterality and cross laterality?

As you might expect, these same rules are embodied in the shape of our brain. We have two cerebral hemispheres, each to the left and to the rightwhich are somewhat like mirror images of each other... at least to the naked eye. In reality, the two hemispheres are very different at the cellular level and, in fact, are responsible for different processes. We are all familiar with the idea that the right hemisphere is rational and analytical, while the right hemisphere is emotional and responds in a special way to music.

These subtle variations mean that for certain tasks we have one side of our body that responds differently to its opposite side, as each of these halves is related to one of the two hemispheres. is related to one of the two hemispheres of the brain.. For example, almost all of us have a dominant hand and consider ourselves right-handed, since we use our right hand for almost everything. However, this fact does not mean that we have one half of the body that is entirely dominant. Interestingly, it is possible for a person to have a dominant right hand, but the opposite is true for his or her eyes or legs. These are cases of crossed laterality.

Cross laterality, homogeneous laterality and dominance

Normally we speak of homogeneous laterality, because people whose dominant hand is on one side tend to have the dominances of the rest of their limbs and senses aligned in that half. Therefore, when we talk about laterality, we are referring to the different dominances that are referring to the different dominances that exist in a person, and the set of those dominances that exist in a personand the set of these dominances will be what defines whether there is a crossed or homogeneous laterality.

In any case, crossed laterality is one more form of laterality, and the existence of one or another type is a consequence of the functioning of our nervous system. This means that it is in the interconnections of our different parts of the body from the nerves where the causes of one or the other type of laterality have to be sought, and this can also be defined by the areas of the body it affects. In this sense, there are different kinds of classes of dominance that serve as criteria to define the type of laterality:

Why does crossed laterality exist?

The nervous mechanisms by which one or the other type of laterality occurs are not very well known, nor why they sometimes occur.It is not well known why sometimes there are cases of crossed laterality, when the majority of cases are homogeneous. In any case, crossed laterality would be a proof that there is no large planning center in charge of coordinating the different dominances or that, if it exists, its function is not essential.

In any case, it is currently believed that crossed laterality could cause some problems when coordinating body parts whose dominance is discordant, for example, when writing. There is a lack of research in this area, but it is considered cautious to to consider crossed laterality as a risk factor in the development of learning disorders in children..

In any case, as the system of connections between neurons on which dominance is based is highly plastic (i.e., adaptable according to our learning and experiences), laterality is not only determined by genetics, but is also influenced by learned behavior. influenced by learned behavior, culture, habits, etc.culture, habits, etc.

Cross laterality is not an exception to this rule, and therefore one can learn to mitigate the effects of a very extreme dominance in order to also use the homologous body part in the other half, in this case we speak of forced laterality.

• Podal dominancedefined by the dominance of one or the other foot for kicking, kicking a ball, standing on one leg, etc.
• Auditory dominancetendency to use one or the other ear more for listening, wearing an earphone, etc.
• Ocular or visual dominancedefined by the dominant eye when pointing with the gaze.