A personality inventory is a test (usually a written, self-reported questionnaire) that attempts to reliably assess or measure various dimensional traits in people. They are intended to apply throughout the entire human population. These tests are structured, meaning they make use of direct questions about a person’s opinions of himself. A good inventory always has unambiguous instructions about how to complete the test.
One very obvious weakness, and potential flaw, of all such self-reported personality tests is that the person completing the test, if she so chooses, can purposefully answer the questions incorrectly in an attempt to manipulate the results. The test administrator has no way of knowing for sure that the test-taker is not cheating or lying on the test, and hence the results are entirely dependent upon a sincere and truthful participant.
That’s very different from a blood test, such as measuring the serum level of cardiac enzymes as is done to evaluate the likelihood of a heart attack. It would be quite hard to falsify the amount of cardiac enzymes that are floating around in one’s bloodstream. However, this kind of intrinsic weakness is not entirely limited to psychological tests. Clearly there are many blood or urine tests that people often attempt to falsify (such as the professional athlete who is trying to avoid the detection of anabolic steroids).
Well-designed personality tests have built-in scales designed to detect erroneous responses and to adjust scores accordingly. Even then, any honest psychologist or psychiatrist will freely admit that a personality test is only as accurate as the person who is “bubbling in” the answers.
Using personality tests is becoming more and more commonplace, even outside of the clinical arena. A recent study by the American Management Association found that 39 percent of all companies surveyed use personality testing as part of their hiring process. These personality inventories are also frequently used in evaluating potential business partners, finding spouses, roommates, and so on. Attorneys occasionally use these tests to analyze criminal behavior, witness examination, and jury selection.
Personality testing is not all fun and games, though. In one noteworthy court case, (Wilson v. Johnson & Johnson) the jury awarded the plaintiff $4.7 million dollars after it was found that the plaintiff’s former employer had caused psychological harm by having him take repeated, and even excessive, personality tests. Wilson claimed that the repeated scrutiny of his personality caused emotional strain, personal grief, and even a nervous breakdown.
Another risk or danger of personality testing is that a participant who is not psychologically strong may come to rely on the results in negative ways. The subject may make assumptions about how he should react in certain situations. That is, he could possibly become complacent about his own personality traits and become overly dependent on the textbook descriptions associated with his personality type. Someone who is not aware of the limits and inherent self-simplification that personality tests can foster could potentially be harmed by such testing.
There are dozens of different personality inventories created by different people, but all are designed to objectively measure personality in adults. And while it is true that multiple theoretical and technical differences exist between the different personality inventories, there is converging evidence that they are measuring the same basic traits (albeit sometimes named differently).
Just to reiterate, the most important traits assessed by any personality test are those in which the test-taker deviates to an extreme. No two humans are alike, and it is most essential to look for “outlier scores” when it comes time to assess which traits are most important, or problematic, for a person. Therefore, the most useful inventories are the ones that give quantitative assessments of personality. Typological tests, which are those that classify people into various personality types but do not give any kind of measure or degree, are less helpful.
Another important point about personality testing is that, no matter how long and detailed a test may be, it can never assess a certain trait in all circumstances. That is, personality, and the associated reactions one has to life events, may not always be consistent across all situations. At times it can be situation-specific.
To give an example, a person may score very high in the trait of impulsivity, but she may not be an impulsive person in all of life’s contexts, just most. She might be more impulsive when it comes to deciding what to eat (that piece of chocolate cake she can’t resist), but less impulsive about spontaneously buying a new piece of clothing every time she turns on the television shopping network. In general an impulsive person is going to demonstrate impulsivity in multiple domains of life, but not always!
Another very consequential aspect of personality tests is that they are not valid on individuals who have altered or deranged mental states caused by a mental illness, intoxication, or whatnot. These tests should only be taken by the mentally healthy and fit. If you are presently suffering from a mental illness and are either untreated or undertreated, you should not take a personality test. The results will reflect more of your illness and not who you are in your premorbid (healthy) state. If you are (or even think you are) presently suffering from major depression, mania, anxiety, or psychosis, do the right thing. Seek the help of a professional. Once you are well and back to your normal self, you can have your personality tested. For now, get treatment for your illness.
Here are a few of the more commonly used personality inventories, as well as some of their strengths and weaknesses.
MYERS-BRIGGS TYPE INDICATOR (MBTI)
The Myers-Briggs Type Indicator is widely used on online dating sites and for other forums of pop psychology. It is based on Carl Jung’s psychological types and was developed during World War II by Isabel Myers and Katherine Briggs. However, at least half of the published research behind this instrument was not done independently (it was carried out solely by the company that markets it), and hence it has a reputation for being less critically validated. Another huge negative is that it is a typological test: It only tells you what type of personality you have (of sixteen different types) and does not tell you how mild or how extreme your traits are in comparison to the general population.
MINNESOTA MULTIPHASIC PERSONALITY INVENTORY (MMPI)
The Minnesota Multiphasic Personality Inventory (and its revision the MMPI-2) provides a wide range of data on numerous personality variables and is backed by a strong research base. However, it tends to emphasize major psychopathology (people with personality disorders) and is not as useful for individuals with more moderate or mild personality tendencies. The MMPI and MMPI-2 can also provide discrepant results. These tests are also considered biased toward the upper socioeconomic status and are not validated in adolescents.
EYESENCK PERSONALITY INVENTORY (EPI)
The Eyesenck Personality Inventory uses a true/false format, is useful as a screening tool, and is backed by a theoretical basis. The test questions are transparent as to purpose. It is generally not recommended for anything other than a screening device.
REVISED NEO PERSONALITY INVENTORY (NEO PI-R™)
The Revised NEO Personality Inventory, also known as the NEO-AC, is the most researched, reliable, and validated personality test available today. It is also the one to be described and referred back to in the rest of this manual.
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