Many blogs advise you to train your non-dominant hand to "stimulate the cognitive and creative functions of the brain" and many Alzheimer's websites say that washing with the other hand improves "brain ability".

The glamorous message is simple: Practice using your non-dominant hand to create stronger connections to the brain hemispheres, becoming a smarter, more capable person. However, while it may seem like a reasonable proposition, researchers say it does not work.

"It's not a bad idea for certain skills to be good on either side," says Michael Corballis, a professor of psychology at the University of Auckland. "But does that make you smarter? I doubt it."

And in fact, the suspicions are apt. A 2016 experiment challenged participants who write with the right hand, to draw shapes with the other hand for 20 minutes each day, for 10 days. Researchers noticed that the sketches began to improve over time, but only so much. No "improvement" was noticed in the brain or anything like that. 

Brain imbalance is a feature, not a defect

Moreover, the idea that one hand is "weak", or defective, is completely wrong because both hands have their own strength. While your dominant hand shines in precise movements, your non-dominant hand has better durability. This is why someone holds a large bundle with his left hand as he opens a door with his right hand.

"Having control in both hands can make you a successful pianist or a legendary tennis player, but I do not think these kinds of changes are related to being smarter in the future," said Benjamin Philip, a neuroscientist who worked in the study done.

Burimi: Brain Facts