extrovert

n. Extroverts (extraverts) are individuals who are high in terms of outward focus. Extroverts are at one end of an introversion-extroversion continuum on which most people fall somewhere in the middle range. Extroverts tend to be outspoken, outgoing, and optimistic. Extroverts tend to have limited interest in solitude, introspection, and quiet pastimes. There is research evidence that extroversion stems, at least in part, from differences in the basic stimulation level of the ascending reticular activation system (ARAS) in the brainstem, commonly referred to as the attention center of the brain. Extroverts have inherently lower levels of stimulation in the ARAS and therefore require more activity in order to stimulate the attention center of the brain. Introverts, on the other hand, are already sufficiently stimulated and therefore require far less outward stimulation. Stimulant drugs such as Ritalin commonly used for treatment of attention disorders operate on this principle; by stimulating the attention center of the brain, the individual becomes less motivated to seek outward stimulation.

- MWP