How does handedness develop?

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Surprisingly enough, good bilateral coordination is vital for handedness to be established!

baby playing with hands

Bilateral coordination skills begin to emerge in early babyhood. Babies love their hands, and they move both hands together to explore or touch something. Moving both hands or both legs together like this is called symmetrical movement. (If your baby under 18months does not move both hands together like this, and tends to leave one hand out completely, then see your doctor or paediatrician urgently)

Some examples of symmetrical movements that we see in older children are jumping and clapping hands.

As the baby grows and develops, he learns to crawl, and in this way, he learns to use each side of the body in a rhythmical way, first one side and then the other. These are reciprocal movements .

Crawling is thus a vital part of a baby’s development, as it gives the baby tremendous opportunities to develop good bilateral coordination in preparation for handedness.

reciprocal coordination tricycle

As the child grows and develops, more reciprocal skills such as walking, running, climbing and riding a tricycle develop. Both sides are doing the same task, one side at a time. Using the hands to pull in a rope is a good example of reciprocal bilateral coordination of the hands.

The next phase of bilateral coordination development is called asymmetrical bilateral coordination . This means that both sides of the body are working together, but they are doing a different, yet complementary task.

coloring activity

Look at this child coloring in. He has developed asymmetrical bilateral coordination as can be seen by one hand holding the paper while the other hand colors with a crayon. Cutting with scissors, drawing on paper, kicking a ball… these tasks all require that one hand or leg is “active” while the other hand or leg “assists”. By age 4, most children have achieved some measure of proficiency in developing this skill.

As the child gets better at getting both hands to work together in a complementary way, the ability to cross the midline begins to emerge.

crossing the midline spontaneously

Crossing the midline means that one hand spontaneously moves over to the other side of the body to work there. In this photo, the child is reaching over to the left with his right hand. This is called crossing the midline.

Before crossing the midline is established, you may have noticed that your young child tends to use the left hand on the left side of the body and the right hand on the right side of the body. So if he is building a block tower with all the blocks in front of him, he will pick up the pieces on the left with his left hand, and the pieces on the right with his right hand. And while drawing, or coloring, he may spontaneously switch hands to color the other side. This is normal for young children!

However, in order for handedness to develop properly, crossing the midline needs to be an established skill. That means that the child needs to be comfortable spontaneously crossing the midline with either hand.

activity for crossing the midline

This will enable the dominant hand to get the practice that it needs in becoming skilled.

How to help your child:

In order for handedness to emerge, your child’s bilateral coordination skills should be encouraged to develop – try some symmetrical and reciprocal activities from my OT Mom e-book: Activities for Bilateral Coordination

If your child avoids crossing the midline, then both hands will tend to get equal practice at developing skills, and your child’s true handedness may be apparently delayed. My article on Hand Dominance explains why it is important for your child to have a dominant hand.

Encourage a strong hand to emerge by making sure crossing the midline is not delayed – try these activities for crossing the midline!

Remember, as well as wanting strong, dominant handedness to emerge, we also want the “other” hand to become a good “assistant”. If your child tends to leave one hand out (not stabilising the paper while writing, or turning the paper while cutting), then keep on doing bilateral coordination activities to help his hands to work together well.

Is your child switching hands? This article may help you to find out why he is switching hands.

Return from Handedness to
Home Page of OT Mom Learning Activities

Fisher, Murray and Bundy: Sensory Integration Theory and Practice (1991)
Dept of Occupational Therapy, Royal Children’s Hospital, Melbourne (Kids Health Information 2005)
Paula Barnard: Skill and Dominance go hand in hand opens in a new browser window

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