Not necessarily smarter, but he/she needs to work harder to use devices made for right-handed people. In this endeavour, he/she probably acquires new skills/ advantages over the majority, right -handed folks.
My father, my son and granddaughter are L. I admired them for having some special skills that I don't.
we are different individuals and for that matter, we all have our strength and weakness so i dont think left handed individuals are smarter than right handed individuals. its all dependent on the individual
I am left handed, I didn't consider myself smarter but always aspiring to do my best. According to Dr. K. Karthik, it may be scientifically proven. Generally, left handed people in the world are mostly extraordinary and exceptional people.
Handedness is further divided into measures of preference and performance. Left-handers have achieved greatness in many walks of life, but particularly in creative, sporting and artistic fields, where their natural talent for lateral thinking and ingenuity have made a huge contribution to all our lives.
Lefthander have always to translate instructions and disciplines generated by righthanders. I'm a surgeon and I had to exercise more the knots , because LH, but now I'm a Bothhander.
Same problems when you are really a native speaker of two different languages.. It's harder, but in yhe summary you are better trained than other people.