Handwriting analysis is based in the principle that personality characteristics can be identified through external movements. The work of Klages and other researchers in the 1920's to 1950's and the earlier 1919 work of Wilhelm Preyer, a professor of physiology and psychology, confirmed that handwriting is a behavior that can be measured, studied, and related to human personality. Such research established that the handwriting movement is physiologically initiated, directed, and controlled by the brain. Handwriting analysis (known as graphology) can be used to identify the potentially violent or unstable individual and to determine whether job applicants have personality and psychological characteristics suitable for particular job tasks. Other uses of graphology include the evaluation of persons for high-security clearance, the assessment of an individual's personality over time, the facilitation of team building, screening for job promotions, and the evaluation of threatening and anonymous letters. Overall, in any situation where security personnel can benefit from knowing more about an individual or a group of individuals, handwriting analysis may be an effective tool. 21 footnotes