5 things you never knew about dyslexia and hand dominance

Which hand do you eat with? Write with?

My son Harry has dyslexia. He also is mixed-handed (he doesn’t have a dominant hand), so is there a connection between dyslexia and hand dominance?

I learned someone could use a different hand depending on the task once he began to scribble. Before then, I assumed he was left-handed because he fed himself with his spoon in his left hand. However, he held the pencil in his right hand when he made marks.

Asking him to set the table can be frustrating. Although I taught him the little phrase, ‘The knife goes on the right,’  he’s never placed knives there. I don’t think this is due to the dyslexic’s left/right confusion. He just doesn’t want his knife on the right of his plate because he holds his knife in his left hand.

Is mixed-handedness connected to dyslexia?

Recently, on a parents’ FB dyslexia forum, someone asked if dyslexia was linked to being left-handed or ambidextrous. This sparked a flood of responses, and it prompted me to investigate the topic of dyslexia and hand dominance.

Michael Corballis, PhD, a psychologist at the University of Auckland, says in an article for the American Psychological Association

“About 90 percent of people are right-handed.
The remaining 10 percent are either left-handed or some degree of ambidextrous, though people with “true” ambidexterity, i.e., no dominant hand at all—only make up about 1 percent of the population.”

The term mixed-handed (or cross-dominant) applies to Harry, who prefers using a particular hand depending on the task, i.e. eating with his left hand and writing with his right.

1. Research has linked dyslexia and ADD to being mixed-handed

An article published in Neuroscience and Biobehavioral Reviews in 2023 identified an association between dyslexia and ‘mixed-handedness.’ In the study context, ‘mixed handedness’ referred to both ambidexterity (no hand preference for a task) and inconsistent hand use (using different hands across different activities.) The authors were surprised to find a robust link between dyslexia and mixed-handedness.

I read in a study published in the journal Pediatrics[i] that

“ADD is twice as likely in mixed-handed people.”

The study also said:

“Around one in every 100 people is mixed-handed. The study looked at nearly 8,000 children, 87 of whom were mixed-handed and found that mixed-handed 7 and 8-year-old children were twice as likely as their right-handed peers to have difficulties with language and to perform poorly in school.

When they reached 15 or 16, mixed-handed adolescents were also at twice the risk of having symptoms of attention-deficit/hyperactivity disorder (ADHD). They were also likely to have more severe symptoms of ADHD than their right-handed counterparts. It is estimated that ADHD affects between 3 to 9% of school-aged children and young people.

The adolescents also reported having greater difficulties with language than those who were left- or right-handed. This is in line with earlier studies that have linked mixed-handedness with dyslexia.”

Dr Rodriguez, who led this study, was at pains to point out that not all people who had mixed-handedness had ADD or learning difficulties, but this fits with my son, Harry, who has ADD and dyslexia.

2. Hand dominance show up early

Have you ever seen a 3D scan of a foetus? My friend showed me one the other day. It was amazing being able to see facial features so clearly. Her baby was sucking its right thumb. According to research[ii] from the 15^th week, most foetuses suck the right thumb rather than the left. Some studies suggest low birth weight and mothers who are stressed during pregnancy can influence the chances of the child being left-handed.[iii]
In his book, ‘Scattered Minds,‘ Gabor Maté has much to say about maternal stress’s role in infant brain development.

3. Hand dominance, like dyslexia, has a genetic component

Research into the genetics of hand dominance has shown that multiple genes are involved, and my book details some of the genes connected with dyslexia. However, environmental factors also play a part. Encouraging left-handed children to use their right hand may lead to mixed-handedness.

4. Mixed-dominance can affect hearing and sight as well as hand preference

Research carried out after patients with epilepsy had their brains surgically split has shown that the two halves of the brain are responsible for different tasks. The left side controls language and the right emotional and nonverbal functions. When a person has a right-hand preference, the brain’s left hemisphere is dominant. Left-brain dominant people tend to be better at analytical thinking, while right-brain dominant are more ‘big picture’ thinkers.

In mixed-handedness, one side of the brain has no clear dominance over the other.

Harry has auditory processing issues; as a young child, he had a squint. In getting to the bottom of these conditions, I discovered most people are right-ear dominant and have a lead eye. Harry is left-ear dominant and doesn’t have a lead eye. A study in 1963 highlighted the role of having a dominant eye in reading success.[iv] In  ‘Dyslexia. Wrestling with an Octopus’, I discuss the interventions we used to correct these issues.

5. Left-handedness and mixed-handedness is often a sign of creativity

Both Leonardo Da Vinci and Einstein were mixed-handed.

According to one study, left-handed people are more intelligent[v].

A 2007 paper in The Journal of Mental and Nervous Disease (Vol. 195, No. 10) found that musicians, painters and writers were significantly more likely to be left-handed than control participants. The author, Corballis, has a theory as to why this is the case:

“Just as information is prone to errors as it traverses between brain hemispheres, it’s also more likely to encounter novel solutions.
Righties might dismiss an idea as too radical, but non-righties might be willing to entertain the thought and develop a solution that a right-hander’s brain would skip right over.
It’s good to have a few people in any society who think outside the square.”

Does your child have mixed-handedness?

If so, are they highly creative?

To read how to teach spelling and reading in 30 minutes a day, click here.

Speechify is an app that can help dyslexic children as it reads online text. Here is my affiliate link.

This post has been update. The reference for the article on dyslexia and mixed-handedness is

Julian Packheiser, Marietta Papadatou-Pastou, Angeliki Koufaki, Silvia Paracchini, Clara C. Stein, Judith Schmitz, Sebastian Ocklenburg,
Elevated levels of mixed-hand preference in dyslexia: Meta-analyses of 68 studies,
Neuroscience & Biobehavioral Reviews,
Volume 154,
2023,
105420,
ISSN 0149-7634,
https://doi.org/10.1016/j.neubiorev.2023.105420.
(https://www.sciencedirect.com/science/article/pii/S0149763423003895)

[i] ” Dr Alina Rodriguez, Mixed-Handedness Is Linked to Mental Health Problems in Children and Adolescents,” Pediatrics, Monday 25 January 2010.  

[ii] Nadja Reissland, Ezra Aydin, Brian Francis, Kendra Exley. Laterality of foetal self-touch in relation to maternal stress. Laterality: Asymmetries of Body, Brain and Cognition, 2014; 1 DOI: 1080/1357650X.2014.920339

[iii] Nadja Reissland, Ezra Aydin, Brian Francis, Kendra Exley. Laterality of foetal self-touch in relation to maternal stress. Laterality: Asymmetries of Body, Brain and Cognition, 2014; 1 DOI: 1080/1357650X.2014.920339

[iv] Irving H. Balow (1963) Lateral Dominance Characteristics and Reading Achievement in the First Grade, The Journal of Psychology, 55:2,323-328, DOI: 10.1080/00223980.1963.9916624

[v] Susie Jeyalyn David, S. Rajasankar. Correlation between handedness and intelligence among schoolchildren. International Journal of Contemporary Medical Research2016;3(9):2683-26