Da Vinci, Michelangelo, Picasso, Mozart, Beethoven, Rachmaninoff, Jimi Hendrix, Paul McCartney, Bob Dylan, Robert Pant, Greg Allman, H.G.Wells, Lewis Carroll, Samuel Clemens, Jim Henson, Spike Lee, Franz Kafka, Friedrich Nietzcshe, Johann von Goethe, Aristotle, Mahatma Gandhi, Benjamin Netanyahu, Albert Einstein, Marie Curie, Isaac Newton, Benjamin Franklin, Albert Schweizer, Linus Pauling, Henry Ford, Jim Lovell, Buzz Aldrin; what is common to all these? Aside from being some of the most brilliant people in their fields, they are all left-handed.
We have seen in our readings that the right side of the brain controls the left side of the body as well as being responsible for creative, holistic, intuitive processing. This being the case, along with the staggering list of left-handed geniuses, makes it easy to see where the idea that southpaws are generally more creative and intelligent than the other 90% of the population comes from, but is there any validity to this notion?
A 2007 study, “Effect of Handedness on Intelligence Level of Students” sought to determine just that. Researchers at the University of Sargodha in Pakistan tested 150 under-graduate, graduate, and post-graduate students, half left-handed and half right-handed, using the Raven Standard Progressive Matrices Test. The results showed that the left-handers turned out to be more intelligent than the right-handers, scoring on average 44.2, where the right-handers average was 39.8. In addition, the right-handers took significantly more time to finish the test than left-handers (Ghayas and Adil, 2007).
Although the study cites several hypotheses that might explain this, more research is needed to prove or discredit these ideas.
The study consisted of 150 students from the Sargodha district only, lending to the possibility of environmental stimuli affecting the outcome. It also makes generalizing the results to the entire population impossible as the sample was not representative of the entire population.

medind.nic.in/jak/t07/i1/jakt07i1p85.pdf