Before describing the major modern trait and type theories of personality the following key terms must be defined; trait, type and personality. A personality trait represents a continuous dimension and can be defined as a broad, stable and enduring characteristic which is used to explain behaviour (Phares&Chaplin, 1997). A personality type is defined by Lefton, (2000 p. 708} as a "personality category in which broad collections of traits are loosely tied together and interrelated" and which people can be grouped into. Personality can be broadly defined (Myers, 1986; Pervin&John, 2001)as the enduring characteristics of an individual that describe patterns of thinking, feelings and behaviour.
             The major modern trait and type theories of Gordon Allport, Raymond Cattell, Hans Eysenck and the Big Five vary in their approach and methods in their attempts to understand personality, yet all share the belief that personality can be understood and individual's behaviour could be explained and described by the use of types and traits. The trait and type personality psychologists used three methods in identifying important traits and types; the lexical approach, meaning the more important a word is the more often it will appear in language, the theoretical approach which focuses on the most significant dispositions and the statistical approach where extensive data is mathamatically analysed {Liebert and Spiegler, 1990) to support their theories outlined in this essay.
             Allport is considered to be the founder of the modern type and trait school. Allport with Odbert, became the first researchers to conducted a lexical study of personality descriptors {cited in Ewen, 1940} and develop a system to classify traits. From the results of this study, Allport developed a theory which divided traits into three groups with varying degrees of influence; cardinal traits, central traits and secondary dispositions, which make up an individuals personali...