What is the definition of handedness? Basically it describes a preference for the use of one hand over the other, which typically provide more precise results. Handedness likely involves a continuous continuum that can be expressed at levels between right and left depending on the type of task or activity involved, rather than being a discrete variable. Four types of handedness are typically recognized: right handedness, left handedness, mixed-handedness, and ambidexterity. Right handedness is most common, meaning that these individuals tend to be more skillful when using their right hand. Some estimates are that left-handers account for about ten percent of the population, with more males than females evidencing a left-handed preference. Mixed handedness (a change in handedness between tasks) may occur in about thirty percent of the population. Some level of mixed handedness can be learned, although the individual still tends to favor their dominant hand—often the left hand. Genuine ambidexterity (able to do given tasks equally well with either hand) appears to be very rare, occurring in about one percent of the population. More tomorrow.