On the contrary, its mostly true actually. Noticed how each side of your brains work differently? If you learn this, you'd know that there are 2 Brain's in your head and each of them functions differently. If you never learn this in school then you'd need a lesson then if not then let me refresh your memories: The left side of your brain functions logical, verbal, analytical, and sequential. While the right side functions intuitive, holistic, creativity, and simultaneous. Because you hand is pretty much doing all the work of how your brain is telling you. The brain starts increasing its functions opposite to what your physically doing to your hand. For instance, I'm left-handed, so clearly my right side of the brain increases its functions. Same applies for right-handed whom applies the opposite.