The left side of the brain controls the right side of the body, as well as spoken and written language, logic, reasoning, and scientific and mathematical abilities. In contrast, the right side of the brain controls the left side of the body and is associated with imagination, spatial perception, recognition of faces, and artistic and musical abilities.

In addition to left- or right-handedness, what other left-right preferences do people have?

Most people have a preferred eye, ear, and foot. In one study, for example, 46 percent were strongly right-footed, while 3.9 percent were strongly left-footed (similar to being right-handed); furthermore, 72 percent were strongly right-handed and 5.3 percent strongly left-handed. Estimates vary about the proportion of left-handers to right-handers, but it may be as high as one in ten. Some 90 percent of healthy adults use the right hand for writing; two-thirds favor the right hand for most activities requiring coordination and skill. There is no male-female difference in these proportions.