The term interests refers to what an individual likes and dislikes, as associated with specific tasks, activities, or objects. Interests are a function of factors such as values, family background and experiences, social class, culture, and environment. For 80 years, interests have been one of the most useful and most enduring constructs in career development. E. K. Strong Jr. and Frederic Kuder were the early trailblazers in interest measurement. More recently, the theory and classification scheme of John Holland has dominated the field. Strong is famous for his resolute empiricism and for creating occupational scales with the method of contrasted groups. Kuder was both a pioneer in psychometrics and a leader in measuring interests with homogeneous content scales. Holland systematized Strong and Kuder’s contributions into a simple, user-friendly, and popular theory and classification. Today, millions of interest inventories are completed each year by young people beginning careers and by older adults considering career changes. The five prominent inventories featured in this entry are well researched, with demonstrated psychometric robustness and distinctive utility for career assessment.
Early interest measurement, notably the leading edge forged by Strong, was largely empiricism devoid of theory. Only more recently, led especially by the theoretical work of Holland, has interest measurement been anchored in theories that explicate interests as constructs with meaning within a theoretical network. Nonetheless, the full understanding of interests within a nomological and causal network is still elementary. We have propositions within social cognitive career theory that suggest interests develop from self-efficacy, but such causal links are still debatable and subject to continuing research.
Two Types of Interest Scales
Strong is best known for creating the occupational scale with the method of contrasted groups. Such scales require intense empiricism to collect data about diverse and contemporary occupations. The Strong Interest Inventory has been routinely revised by collecting samples of men and women in diverse occupations. In the latest revision, David Donnay and his colleagues followed the procedures Strong created for constructing occupational scales. Separate occupational scales were created for women and men, based on the somewhat different interests of women and men in general, and sometimes within specific occupations. Thus, Donnay and his colleagues created a new occupational scale for female rehabilitation counselors and a new scale for male rehabilitation counselors. The steps can be described using female rehabilitation counselors as an example. The rationale for an occupational scale is to differentiate people in that occupation from a general sample of workers representing a broad cross section of the workforce. High scores on a scale indicate that the person shares the likes and dislikes that differentiate people employed in that occupation from people in general. Thus, in this contrasted-group method, the responses of 254 female rehabilitation counselors were compared with other women on each of the 291 items in the newly revised Strong inventory. Items on which they differed in either the like or the dislike direction by 19 percent or more became the 38 items in the female rehabilitation counselor occupational scale. Some things that female rehabilitation counselor like more than other women are not surprising, such as psychology, career counseling, and motivating other people. Female rehabilitation counselors are differentiated more by their likes than their dislikes; however, they tend to dislike making computer databases and diagnosing computer problems more than do women in general.
It could be said that interest measurement has been hindered by its own success. Strong’s creation of the empirical occupational scale was hailed as such a success in academic circles that conceptual progress in interest measurement was perhaps delayed. The occupational scale, actuarially defined by the items empirically distinguishing the people in that occupation, was an apt metaphor for the “dustbowl empiricism” of the 1930s and 1940s. But this kind of contrasted-groups scale has conceptual limitations. An occupational scale is not readily interpretable other than by the actuarial locution “You have the interests of X.” A high score on, for example, the physicist scale, does not directly tell the interpreter that it means the person loves science, math, and mechanics but abhors selling, entrepreneurship, and marketing. Interpretation of such a scale becomes inscrutable. This problem led to the development of homogeneous content scales.
The Kuder Preference Record, developed in the 1930s, was the first popular interest inventory to use homogeneous content scales. In contrast to Strong’s occupational scales, Kuder designed a content scale to be directly interpretable because its items reflected similar content. Such items tend to correlate with each other, and thus such a scale has internal consistency. Today, content scales are present in nearly all major interest inventories. Many use content scales to measure the six broad Holland RIASEC (Realistic, Investigative, Artistic, Social, Enterprising, and Conventional) domains. Others, such as the Campbell and Strong inventories, also have specific content scales, called Basic Interest Scales (BISs). For example, the newest Strong revision has 30 BISs, measuring such specific dimensions as interest in protective services or entrepreneurship.
Major Current Interest Inventories
The five most widely used interest inventories are the Campbell Interest and Skill Survey (CISS), the Kuder Career Search with Person Match (KCS), the Self-Directed Search (SDS), the Strong Interest Inventory (SII), and the Unisex Edition of the ACT (UNIACT) Interest Inventory. The SDS and UNIACT inventories are the least complex of these inventories; they primarily measure the six Holland RIASEC dimensions. Because of their large number and kinds of scales, the most complex inventories are the Strong and the Campbell inventories. The Kuder inventory uses fewer scales, but it is also currently the most innovative of the inventories because of the way it is being used for an online career-assessment system. The utility of these inventories has been extensively supported by research. Interest scales effectively differentiate and predict important career behaviors such as career choice and persistence, college major, and educational aspirations.
The Campbell Interest and Skill Survey (CISS) is one of the more recent interest inventories. It has quickly become popular because it has many of the assets of the Strong inventory but also because Campbell added innovative measures of self-rated skills that parallel the interest measures. The CISS is the latest of these inventories. Campbell brought many key advances to the Strong inventory during the 1960s and 1970s. In his CISS, he replicated many of the valued attributes of the Strong inventory. Using a Holland-like organizational structure, the CISS contains broad scales similar to the Holland dimensions, basic interest scales, and occupational scales. Campbell chose to rename the Holland RIASEC dimensions in more common language; for example, the Enterprising dimension became “Influencing.” He also added a seventh general scale called “Adventuring.” The notable innovation of the CISS is the addition of self-rated skills that match the interest scales. Skills and interests in the same domain are plotted together so that their matches or mismatches are evident. This leads to a qualitative shift in how an interest inventory might be used, especially when interest for an activity is high and the parallel skill is low (or conversely). Such mismatches lead to a counseling dialogue about how the person might seek experiences to gain interest or skill. Campbell’s addition of skill ratings stimulated the Strong and Kuder publishers to add similar skill self-ratings as companions to their interest measures.
The Kuder Career Search with Person Match (KCS) was originally developed by Frederic Kuder. Kuder is recognized as one of the most important early figures in interest measurement. The Kuder legacy is now carried on by Donald Zytowski, who has infused Kuder’s work into a leading comprehensive online career assessment and exploration system. This system is called the Kuder Career Planning System, under the auspices of the National Career Assessment CAP System, Inc. Its interest inventory is now called the Kuder Career Search with Person Match, and it has many of the features of what was previously called the Kuder Occupational Interest Survey. Kuder’s approach heavily focuses on interests as rank ordered. Interest items are presented in triads, and the respondent selects the most-liked and the least-liked activity in the triad. The KCS inventory is scored for six dimensions that are similar to Holland’s RIASEC but with different names. These scores are then ranked to give a three-point code, very similar to the Holland system, which then permits the Kuder system to link to rich sets of educational and occupational databases, such as the Occupational Information Network (O*NET). The individual’s interest results are scored by “person matching” to an archive of personal occupational vignettes of people with similar interests. The online interactive system also includes assessments in self-rated skills (Kuder Skills Assessment) and in values.
Following John Holland’s goal for simplicity and utility, the Self-Directed Search (SDS) is one of the simplest interest inventories, yet it is widely used. In a self-scored format, it assesses the six RIASEC dimensions of Holland’s theory. It contains four different kinds of items in separate sections of the inventory: Activities, Competencies, Occupations, and Self-Estimates. The Competencies and Self-Estimates items are more like indicators of self-efficacy. Adding these kinds of items to the more interest-like items of activities and occupations yields RIASEC Summary Scores, tapping a mix of interests and self-rated competence. Thus, these scores are different from those for inventories such as the Strong and the Campbell, which assess those domains separately. From the ranking of the six summary scores, a three-point code (or type) is derived to denote the person’s highest RIASEC scores. Such codes are widely used to identify occupations and college majors with similar Holland codes. There are many published studies on the SDS showing its reliability, validity, and utility for stimulating career explorations.
The Strong Interest Inventory (SII) is typically revised each decade to keep it current with career trends and to update its occupational scales, the hallmark of the SII since the 1920s. The SII is the most data-driven interest inventory, given its occupational scales, its large national norm groups, and the number of articles about it appearing in the literature. Over the years since the 1960s, SII revisions have successively incorporated several sets of content scales: first, the Basic Interest Scales, then the Holland General Occupational Theme Scales, and more recently, the Personal Style Scales. In the newly revised version, the SII contains 244 occupational scales, representing the same 122 job titles for women and men, marking the first time since its inception that the inventory includes the entire set of occupational scales for both genders. The SII can also be used with the companion Skills Confidence Inventory, which measures confidence in each of the six Holland RIASEC dimensions.
The UNIACT Interest Inventory (UNIACT) is available to American high schools, colleges, and many others as a component of ACT’s educational and career development programs, such as the ACT assessment and PLAN. Used by nearly 5 million people each year, the UNIACT inventory is the world’s most frequently used interest inventory. First published in 1977, this inventory contains 90 items, 15 per each of six scales, corresponding to the six RIASEC interest types. Items emphasize work-relevant activities that are familiar to people, through either participation or observation. Occupational titles and job duties are not used. The full name of UNI-ACT, the Unisex Edition of the ACT Interest Inventory, reflects special efforts to identify interest items that assess basic interests while minimizing gender differences. Individuals’ scale scores are used to plot their location on the World-of-Work Map, an extension of Holland’s hexagon. The UNIACT inventory is a core component of DISCOVER, ACT’s Internet-based computerized comprehensive career guidance and planning system.
Quality and Utility of Interest Measures
Individual differences in vocational interests are huge in most general groups of people. The consequences are manifold. For test developers, it means most people can readily express their passions and aversions by responding to simple, straightforward inventories. Interest scales built from such inventories have potent psychometric properties. They have high reliability of several kinds, notably internal consistency and temporal stability. Such interest scales also exhibit some of the best validity indicators in psychology. There is a large and venerable literature on the validity of vocational interests for differentiating occupational and educational groups and for predicting career outcomes. Many of the suggested readings at the end of this entry address such issues.
Especially in the hands of a skilled career counselor, interest inventories can be useful in several ways. The best use will help clients better understand themselves and their vocational options and stimulate directions for action. Best practices in vocational assessment blend subjective information from counseling with objective information, such as interest inventories, to reveal the client’s career story.
Broad scales, such as Holland’s RIASEC scales, and specific scales, such as basic content scales, have different roles to play in counseling and in self-understanding. The broad scales are readily understood and readily organize broad career options. They are the best place to start the process of formulating a career story and charting directions for exploration. The specific scales then supplement this broad information when clients start refining their career stories and more precise paths for exploration. A broad Enterprising scale points to a broad venue of influencing, yet more precise scales such as Merchandising and Public Speaking relate distinctively to the options of retail sales versus politics. The specific scales are especially useful in identifying client strengths because there are a larger number of them, and therefore they are more likely to show some high scores indicating areas of interest.
By young adulthood, the passions and aversions of most people are clear and affect the choices they make. The likes and dislikes of people in different educational and occupational venues are often sharply different. For example, in the norm group for the 1994 version of the Strong inventory, 148 of 200 women airline attendants liked “looking at things in a clothing store” versus just 66 of 200 women physicists. For these same women, 131 of the flight attendants disliked calculus as a school subject versus none of the physicists.
The fact that individual differences in interests are very wide and deep also has positive consequences for a complex society. Whatever activities are needed to make a society function, there is a likely a group of people eager to tackle that task. Fortunately, there are some people who variously love computer programming, cleaning teeth, harvesting a field of wheat, diagnosing diseases, comforting the distraught, or making sales calls to reluctant customers.
Vocational interests have been the cornerstone of career assessment and counseling for 80 years. Interests deeply tap enduring and important individual differences and play a key role in defining a person’s identity. What a person variously likes or dislikes—math, public speaking, using a torque wrench, reading about DNA, trading stocks, or bungee jumping—does much to define that person. This distinctive individuality is powerfully related to life activities such as learning, working, playing, and relating to other people.
- Betz, N. E., Borgen, F. H. and Harmon, L. W. 2005. Skills Confidence Inventory Manual: Research, Development, and Strategies for Interpretation. ed. Mountain View, CA: CPP.
- Borgen, F. H. and Lindley, L. D. 2003. “Optimal Functioning in Interests, Self-efficacy, and Personality.” Pp. 55-91 in Counseling Psychology and Optimal Human Functioning, edited by W. B. Walsh. Hillsdale, NJ: Lawrence Erlbaum.
- Campbell, D. 2002. “The History and Development of the Campbell Interest and Skill Survey.” Journal of Career Assessment 10:150-168.
- Donnay, D., Schaubut, N., Morris, M. and Thompson, R. 2005. Strong Interest Inventory Manual: Research, Development, and Strategies for Interpretation. Mountain View, CA: CPP.
- Hansen, J. C. 2005. “Assessment of Interests.” Pp. 281-304 in Career Development and Counseling, edited by S. D. Brown and R. W. Lent. New York: Wiley. Holland, J. L. 1997. Making Vocational Choices. 3d ed.
- Odessa, FL: Psychological Assessment Resources. Larson, L. M., Rottinghaus, P. J. and Borgen, F. H. 2002. “Meta-analyses of Big Six Interests and Big Five Personality Variables.” Journal of Vocational Behavior 61:217-239.
- Savickas, M. L. 1999. “The Psychology of Interests.” Pp. 1956 in Vocational Interests: Their Meaning, Measurement, and Counseling Use, edited by M. Savickas and A. Spokane. Palo Alto, CA: Davies-Black.
- Zytowski, D.G. 2001. “Kuder Career Search with Person Match: Career Assessment for the 21st century.” Journal of Career Assessment 9:229-241.