Lateralization of the brain functions
The lateralization of the brain functions happen around the age of 4 to 5 years old and is in fact a gradual specialization of the two hemispheres in their respective functions and results in precedence of the left hand or the right hand. Research has shown that when a person shows a preference for the right hand, the left hemisphere is more dominant than the right, while the opposite is true for a lefty. According to various studies, we can now find about 83% of people that are right-handed, 14% left-handed and 3% of ambidextrous.
Stages of development
- Around 4 to 5 months, when your child begins to grasp objects, you may be able to notice he always grabs things with the hand that is on the same side (for example if the object is on his right, he will grab it with his right hand).
- At 9 months, your child will start experimenting and try to cross the midline of his body. You can already start seeing which hand he seems to prefer, which is the first indication of his laterality.
- It’s not until the age of 5 that children will begin to distinguish between their right hand and their left hand.
- Laterality can be observed on the hands but also with the eyes, ears and feet.
Some things to look for
It’s possible to check your child’s preference in some daily activities.
- Let him climb up the stairs and look to see with which legs he starts.
- Similarly, you can see which way he throws or kicks a ball.
- Give him a kaleidoscope (or make a long-view paper) and notice the eye with which he looks inside.
- Give him an alarm clock: which ear is he using to listen to the ticking?
Finally, be aware of all the gestures of everyday life: how he holds his toothbrush, spoon, toys, pens…
If the actions performed always done with the same hand, odds are good that this is the hand he will use in the future, but it could still change along the way. If you see that he is using his right hand as much as his left hand, perhaps he is not ready yet or maybe he will be ambidextrous and able to use both his hands easily.
Left-handed
You have a little lefty at home or are one yourself? Long considered to be abnormal for cultural or religious reasons, left-handed people saw themselves receive corporal punishment or were even forced to use their right hand. Fortunately, attitudes have changed and the majority of left-handed people today live a perfectly normal life. In some areas, being a lefty is even considered to be an advantage!
Although today’s society is much more suited for left-handed people than it once was, there are still some minor annoyances to deal with when you are a lefty. Nothing serious of course and lefties learn to live with these differences with humor as evidenced by the moms on our Facebook page:
- I have 3 lefties at home. Cutting, tying shoes, very difficult to teach when mommy is right-handed! – Virginie Marcouiller-Trudel
- Writing tests in pencil, my arm got so dirty! – Geneviève Poulin
- My husband, my son and I are lefties! My challenges: opening a can, teaching children I work with how to write or cut things! At least I can help my own son! – Marie-Pier Pelletier
- Writing without getting dirty was always a challenge until the day I decided to bend my sheet to the right. I basically write up to down and the problem is solved. You just have to find solutions. – Myriam Marier
Being ambidextrous
To date, there is little known information that explains the fact that a person is ambidextrous and able to use both hands just the same. Some researchers have hypothesized that ambidexterity may in fact be explained by a manifestation of a different pattern of dominance which makes it difficult to identify which hemisphere is actually dominant.
Interesting numbers
- There are 30% of real lefties at birth and 10% remain in adulthood.
- Two left-handed parents give birth to a lefty in 46% of cases.
- One left-handed parent gives birth to a lefty in 17% of cases.
- Ambidexterity is often lost in school or parents request the child uses only the right hand.
- A study of human fetal ultrasound revealed that about 8% of fetuses suck their thumbs in the womb. 92% of them suck their right thumb while 8% suck their left. In almost all cases, this trend left/right is confirmed when the baby is born.
- Studies tend to show that if both parents are right-handed they have a 10% chance of having a child who is left-handed.
- With lefties, their left side is not necessarily always dominant: indeed, 43% of lefties have a dominant right eye and only 45% of lefties will actually kick a ball with their left foot. For right-handed people, 95% will use their right side for their hands and feet.
- There are a little bit more left-handed men (12.5%) than women (10%).
Sources: RIRE, Hebdo-Web, My child’s development by Éditions du CHU Sainte-Justine, Santemagazine.fr.
