Dr. María Eugenia Russi Delfraro explains that most people have a natural preference for one side of their body; this is called “laterality”. This side is usually the right (in the case of right-handed people) or the left (in the case of left-handed people). When the person is able to use both sides of the body indifferently and with equal skill, he/she is called ambidextrous.
What is cross laterality?
However, the dominance of one side of the body is not always constant (for example, an individual may write with the right hand, but be more skilled at kicking a ball with the left leg, or conversely write on the blackboard with the left hand and focus the lens of a lens with the right eye). This is what is known as “crossed laterality”, and is an innate characteristic of certain people (such as eye or hair color), and does not cause any problems for those who present it.
In children the same thing happens, although manual dominance is usually fairly well defined by the end of the first year of life, sometimes it can remain unstable and not fully defined for a long time (even up to 6 years of age), as part of the normal maturational process of the growing brain.
Who diagnoses crossed laterality?
It is always up to the pediatrician to diagnose whether there is a “forced dominance”, that is, whether the child is left-handed because there is a disorder of the right hand or a hemiparesis that prevents him/her from using it, or whether he/she is ocular dominant because the contralateral eye has a vision defect (referring in the first case to the neuropediatrician and to the ophthalmologist in the second case). What happens is that in the past it was a common belief to consider “crossed laterality” as the cause of certain learning disorders.
Fortunately, thanks to the progress of neurosciences, professionals dedicated to the study of different neurodevelopmental disorders and learning difficulties, we have scientific evidence that proves beyond any doubt that the non-homogeneous domain between hand-foot and eye (also known as crossed laterality) not only does not entail or predispose to any pathology or learning difficulty in particular, but it is an obsolete and clinically insignificant denomination.
Today we know that certain treatments based on saccadic or eye-tracking movements, exercises to improve balance or hand-eye coordination and special glasses are based on uncontrolled studies and anecdotal cases, and therefore not only show no usefulness in the treatment of different learning disorders (including dyslexia), but also prevent the child from receiving the correct psychoeducational treatment early.