The Holland Codes or the Holland Occupational Themes (RIASEC) refers to a taxonomy of interests based on a theory of careers and vocational choice that was initially developed by American psychologist John L. Holland. The Holland Codes serve as a component of the interests assessment, the Strong Interest Inventory. In addition, the US Department of Labor's Employment and Training Administration has been using an updated and expanded version of the RIASEC model in the "Interests" section of its free online database O*NET (Occupational Information Network) since its inception during the late 1990s. Overview Holland's theories of vocational choice, The Holland Occupational Themes, "now pervades career counseling research and practice". Its origins "can be traced to an article in the Journal of Applied Psychology in 1958 and a subsequent article in 1959 that set out his theory of vocational choices. ... The basic premise was that one's occupational preferences were in a sense a veiled expression of underlying character." The 1959 article in particular ("A Theory of Vocational Choice", published in the Journal of Counseling Psychology) is considered the first major introduction of Holland's "theory of vocational personalities and work environments". Holland originally labeled his six types as "motoric, intellectual, esthetic, supportive, persuasive, and conforming". He later developed and changed them to: "Realistic (Doers), Investigative (Thinkers), Artistic (Creators), Social (Helpers), Enterprising (Persuaders), and Conventional (Organizers)". Holland's six categories show some correlation with each other. It is called the RIASEC model or the hexagonal model because the initial letter of the region is equal to R-I-A-S-E-C when it is expressed as a circle connecting the regions of high correlation. Professor John Johnson of Penn State suggested that an alternative way of categorizing the six types would be through ancient social roles: "hunters (Realistic), shamans (Investigative), artisans (Artistic), healers (Social), leaders (Enterprising), and lorekeepers (Conventional)". Holland offers full definitions of each type in his book, Making Vocational Choices: A Theory of Vocational Personalities and Work Environments (Third Edition)’’ (1997). According to the Committee on Scientific Awards, Holland's "research shows that personalities seek out and flourish in career environments they fit and that jobs and career environments are classifiable by the personalities that flourish in them". Holland also wrote of his theory that "the choice of a vocation is an expression of personality". Furthermore, while Holland suggested that people can be "categorized as one of six types", he also argued that "a six-category scheme