Definition:  Tests assessing individual differences on personal and vocational traits.

        Description.  Most personality and interest tests are self-reports.  Historically, developers of personality tests have believed that personality, like intelligence, was consistent across persons and independent of situations (Danziger, 1990).  Based on studies employing a variety of research methodologies and samples, personality researchers have become increasingly confident that long-term stability of personality traits exists. West and Graziano (1989) concluded that research studies have demonstrated substantial long-term stability of personality in children and adults.  They also noted, however, that (a) stability declines across longer measurement intervals, (b) is lower in children, and (c) depends on the particular traits measured.   Moreover, predictions of personality from one time point to another typically account for only about 25% of the variance in scores, leaving considerable room for environmental and person-environment influences.

Swanson and Hansen (1988) found similar results with the stability of vocational interests:  although individual variability and environmental influences existed, trait stability could be demonstrated over time.  Staw and Ross (1985) found that job satisfaction remained stable in a sample of 5,000 middle-aged men even when they changed jobs and occupation.

Vocational interests are generally considered distinct from such constructs as ability and aspirations.  Vocational interest tests ask individuals to report their likes and dislikes for various activities (e.g., working outdoors, working with people, doing clerical tasks).  Developers of interest tests must create extensive norms of interests for persons in a wide variety of occupations.  An individual’s interests are then matched to these groups, with the assumption being that the field of closest match is likely to hold the greatest job satisfaction for the test-taker.  Examples of current interest inventories include the Strong Interest Inventory, the Kuder Occupational Interest Survey, and the Self-Directed Search. Research evaluating the Strong Interest Inventory (SII) found test-retest reliability for one- and two-week periods exceeds .90, but drops into the .60s and .70s when the retest interval exceeds a year for respondents under 25 years of age. The SII has proven useful in predicting which occupations individuals do and do not enter.For a relevant video, watch here.

Much empirical evidence, however, shows that behavior is highly responsive to environments.  Mischel (1968) contended that personality constructs were unstable, that is, the influence of traits was relatively small compared to the influence of situations or environments:  “What people do in all situations and on all tests can be affected, often quite readily, by many stimulus conditions and can be modified substantially by numerous environmental manipulations” (p. 10).  Mischel favored measuring behavior in specific situations as opposed to measuring signs of underlying mental processes that could presumably predict future behavior.

The most well-known personality test, the Minnesota Multiphasic Personality Inventory (MMPI), underwent a revision to become the MMPI-2 and MMPI-3. Butcher (1990) described the MMPI as a screening device useful for information about an individual’s strengths and weakness.  He maintained that “clinicians and researchers using the MMPI in treatment evaluation have long been aware of the stability of MMPI profiles over time” (p. 10).  Yet Graham’s (1990) review of stability data and other psychometric properties of the MMPI-2 paints a different picture.  Test-retest data of one week for 13 MMPI-2 scales, as cited in the MMPI-2 manual (Hathaway et al., 1989), ranged from .58 to .92 with a median value of .81.  In contrast, the stability of a more frequently used MMPI score, the two-point code (i.e., the highest two scales), was fairly low:  only about one-fourth to one-third of subjects in research studies show the same two-point code.  Most MMPI-2 scales also appear to be multidimensional given that a sample of coefficient alphas for 13 MMPI-2 scales ranged from .34 to .87 with a median of .625.  Two major factors that emerge from factor analyses of the MMPI-2 are maladjustment-psychoticism and neurotic characteristics. Here’s an extensive video.