Right side of body is associated with left side of brain and visa versa.
It’s likely your non-dominant hand is permanently stuck at about 4 years old. Motor skills, coordination, etc. In short, it’s clumsy.
But as you improve its abilities, there’s a corresponding “upgrade” in the brain. Where? Probably mostly the motor cortex but it’s possible there’s other benefits as well. For example, one might get more observant.
Reaching and grabbing for obects is one I’m thinking of. Your arm has a certain “swath” it travels in. An arc, with a bendy elbow, wrist, hand and fingers.
But there’s another one on the other side of your body which creates a different arc, a bendy elbow that isn’t the same, different wrist, hand and fingers.
So, let’s say you reach for things to the left because you’re righty. (reach across body to the left, to grab something).
But if you start reaching and grabbing things with the left arm/hand, suddenly your attention is changed. You look to the right for stuff when previously you might only look to the left, because that’s where you’d always grab for things.
Just speculation on my part and train of thought.
k let’s see what interesting things a search brings: Ah – there’s this:
They once thought handedness was uniquely human, but chimps show _some handedness_. Yet, humans appear to be unique in the specialization in our brains.
WAIT! Nope. Not uniquely human. I should’ve read further! Apparently, even in many scientific circles, the way we specialize language and such and handedness is thought to be unique but more proof is mounting up that no, it’s not so unique. Even still, even in 2017, it remains a common scientific myth that it’s uniquely human. Love when the sciences duke it out over stuff.
Ah! But this article claims that learning to be ambidexterous makes things worse. The plot thickens.