Diana Deutsch is a perceptual researcher who made discoveries about left-handedness and pitch perception. Her more important discovery is that people who grow up speaking tonal languages like Mandarin have a greater advantage in the pitch component of musicality. About left-handedness, her findings: 40% of the 10% of the population who are left handed, have a brain neurology that is just an opposite mirror of the 90% of right handers. 60% of left-handers, the people who have a higher proportion of perfect pitch, have “mixed hand preference”, in which they will switch off between hands for common tasks (switch hitters). (My father broke his...