Explorations of a Theory of Vocational Choice

The series tested Holland's theory that vocational choice is an expression of personality, and that people seek work environments congruent with their personality types. The first monograph, a one- and two-year longitudinal study, examined high-aptitude students using the Vocational Preference Inventory . The second, a four-year prediction study, found that congruence between student type and college type was conducive to student stability in vocational choice and major field . Student stability and achievement were more closely related to personal attributes, though related to both personality and institutional attributes . The combined results generally supported the theory's usefulness.

The studies used the Vocational Preference Inventory (VPI) to define personal constructs and the Environmental Assessment Technique to define environmental constructs . The VPI, composed entirely of occupational titles, assumed that preferences for occupations are expressions of personality . The Environmental Assessment Technique characterized colleges by their environmental types. By classifying both students and colleges into Holland's six types—Realistic, Investigative, Artistic, Social, Enterprising, Conventional—researchers could calculate congruence and test whether it predicted outcomes like stability in major field and vocational choice.

Part I (1962) was a one- and two-year longitudinal study of two samples of high-aptitude students . Part II (1963) was a four-year prediction study of a single high-aptitude sample . Part III (1964, with Nichols) examined change in major field of study over one year using National Merit Finalists . Part VI (1968) used a sample of typical college students rather than high-aptitude students . The progression moved from short-term to longer-term prediction, and from elite samples to more representative college populations, testing the theory's generalizability.

The four-year study found that students who resembled the theoretical models possessed the hypothetical traits attributed to each model . Congruence between the student type and the college type was conducive to stability in vocational choice and major field . However, the study also concluded that student stability and achievement are more closely related to personal attributes than to environmental ones, though they are related to both . This nuance complicated the simple congruence hypothesis: the environment mattered, but personal characteristics carried more explanatory weight for stability outcomes.

The 1968 study (Part VI) used large, diverse samples of college students rather than the high-aptitude National Merit samples of the earlier studies . The testing of concurrent and predictive relationships based on the theoretical formulations was generally positive . Analyses of student-college interactions were partially successful . The combined results supported the usefulness of the theory . This study was important because it addressed a limitation of the earlier work: whether findings from elite samples would generalize to typical college populations, and the answer was broadly affirmative.

The Explorations series consists of journal monographs and articles published between 1962 and 1968, testing specific hypotheses from Holland's 1959 theory paper. These empirical reports provided the evidentiary foundation for the systematic statement in The Psychology of Vocational Choice (1966), and later for Making Vocational Choices (1973, revised 1985, 1997). The 1969 occupational classification report by Holland, Whitney, Cole, and Richards introduced the hexagonal model ordering the six types by psychological similarity, refining the classification used in the Explorations studies . The series thus marks the transition from theory to tested framework to mature system.