Personality Assessment methods
September 2011
Psychologists use a variety of methods in order to conduct assessments and arrive at recommendations. The key to competent evaluation of individuals is what is referred to as multi-modal assessment. Multi-modal assessment involves the use of different methods from different domains (e.g,, different classes of tests, interviews, review of records, collateral sources such as family members). Only this approach ensures that the most valid conclusions are drawn. As Professor Gregory Meyer of the University of Toledo has stated, "The evidence indicates that clinicians who use a single method to obtain patient information regularly draw faulty conclusions." This is because of what psychologists refer to as "method variance," that fact that individuals can appear differently when different methods are used to gather information. Thus, for example, a patient who seems quite untroubled during an interview, may appear to have significant pathology on a personality inventory. This may happen, for instance, when an individual is reluctant to admit to certain symptoms or disturbing thoughts in a face-to-face encounter, but is more self-revealing when filling out a paper-and-pencil test. Patients may even have different results on different tests; an individual who is highly defensive on a true-false inventory may reveal much about himself on a free response test such as the Rorschach. Of course, the converse is also often true as well. When we gather information from multiple sources and then integrate this information into a comprehensive formulation, we are much more likely to draw appropriate conclusions and to make recommendations that referrers (other clinicians, courts, schools, etc.) will find most helpful. Below are descriptions of some of the common methods that psychologists use to conduct assessments:
Interview
The most basic information-gathering tool is, of course, the interview. Psychologists are trained to conduct interviews in a manner that encourages honesty, forthrightness, and self-reflection. Interviews may be structured (a set list of questions that doesn't vary), semi-structured (similar to structured interviews, but with more leeway for follow-up questions, etc.) or unstructured (open-ended interviews in which the subject's own associations often dictate the direction the interview takes). Which of these techniques is used typically depends upon the purpose of the assessment. In so-called "high-stakes assessments" (e.g,, criminal cases, public safety employee screening), a more structured approach may be used in order to reduce the possibility of bias. On the other hand, in clinical cases, a more unstructured approach is frequently indicated in order to foster a more therapeutic relationship and encourage the patient to reflect upon him or herself.
Self-Report Tests
These paper-and-pencil tests, sometimes referred to as forced-choice instruments because the subject must choose between a limited number of possible answers (e.g., true-false, or a scale of 1-3, etc.), contain questions or statements that the individual rates as true or not about themselves. Some of these are single issue tests, such as those designed to rate the level of depression or anxiety that a person is experiencing. Others are comprehensive inventories that yield scores on multiple scales measuring different aspects of an individual's personality. These inventories have been developed empirically, meaning that the various scales have been found to differentiate different groups of patients (e.g., depressed from schizophrenic) or predict certain behavior patterns. Typically, interpretation involves the analysis of profiles, that is not only the scores on individual scales, but the relationship between the scores on the various scales. Although there are computer programs that do some of the work of interpretation, only highly trained assessment psychologists can properly interpret the profile of an inventory such as the MMPI-2 (Minnesota Multiphasic Personality Inventory-2) or the PAI (Personality Assessment Inventory). In addition, most of these inventories have sophisticated validity scales, which are indicators designed to reveal over or under reporting of symptoms or conscious attempts at impression management.
Performance-Based Tests
The other main class of psychological instruments are called performance-based tests or free-response tests. These are distinguished from self-report inventories in that the subject is typically asked to perform a task (e.g., interpret an inkblot, tell a story to a picture, complete a sentence). Various inferences about the individual's personality may be drawn from the way in which s/he engages in this task. The tests are "free-response," in that there are no constraints placed on what the person may say in response to the task. These tests used to be called "projective," because it was thought that the person projected his or her personality into their responses. This term has fallen out of favor, however, because recent research has demonstrated that the response process is more complex than simply a projection of one's personality. In addition, there is little agreement among psychologists as to the definition of the term projection.
The most well-known of these tests is the Rorschach (usually referred to as the Rorschach Inkblot Method). In recent years, there has been some controversy about the Rorschach that has made its way into the popular press. Although there are some psychologists who are skeptical about it, the vast majority of assessment psychologists find it to be a valid and useful method of personality assessment. Because it is not a self-report inventory, it is not subject to some of the same kinds of manipulation. Research has demonstrated that inferences drawn from the Rorschach have about the same validity as those drawn from well-validated inventories. It appears that the Rorschach is more valid for certain kinds of questions and self-report inventories for others. A comprehensive assessment that utilizes instruments from both classes of tests is most likely to yield reliable information.