MMPI and MMPI-2 Validity Scales in Psychology

In any psychological testing situation, validity is extremely important. There is no point assessing an individual is the data collected is not going to be valid or accurate. Failure to meet validity requirements can result in erroneous diagnosis or misunderstandings concerning the patient's situation and diagnosis. The MMPI and MMPI-2 is a hard-hitter in the personality testing arena. Watkins et al. (1995)* report that 80% of clinical psychologists use the latest MMPI, the MMPI-2, in their assessment of clients. However, because the MMPI-2 is so widely implemented, it is also important that it bears a high ranking in the validity department.

The first four validity scales of the MMPI-2 were also present on its predecessor the MMPI. These four are the Cannot Say Scale (?), Infrequency Scale (F), Lie Scale (L), and the Defensiveness Scale (K). Each of these scales measure different levels of validity within the MMPI-2 assessment.

Cannot Say Scale (?): A scale used to measure the number of items on the assessment that were left unanswered.

Infrequency Scale (F): A high score on the "F" scale generally suggests that deviant responses were given. The "F" scale hints at "extra test characteristics or behaviors" (Trull, 2005). Meaning, if a person has a tendency toward exaggeration of their symptoms, the "F" scale will pick it up and make this assessment tendency and inaccuracy known to the tester.

Lie Scale (L): This scale is fairly self explanatory. The Lie Scale is the set of questions in the MMPI used to detect whether an individual is making themselves seem more well adjusted than they actually are. Trull (2005) explains this an individuals that wish to present themselves in a more positive light.

Defensiveness Scale (K): A very subtle scale used to pick out respondent's tendency to fake on the test in order to make themselves look better. While the Lie Scale and the Defensiveness Scale seem similar, the Defensiveness Scale focuses on lies due to "defensiveness in admitting problems" (Trull, 2005), and is done extremely subtly; whereas the lie scale detects simple lies meant to cast a better light on oneself.

Each of these are built into the assessment in order to better understand the motivation of the individual taking the assessment. Since assessments such as the MMPI are meant to gauge one's personality in order to better understand them, it is important that a complete and accurate understanding is actually reached. Malingering, or any other inaccuracy, can lead to serious inaccuracies in diagnosis, therapy, and treatment of an individual.

In addition to the traditional scales on the MMPI, the latest MMPI-2 contains an additional three validity scales.

Back Page Infrequency (Fb): Detects one's tendency to exaggerate one's problems. These items are frequently endorsed during assessment.

Variable Response Inconsistency (VRIN): Detects random responses on the exam. Detects whether an individual is answering truthfully. Opposite question sets are used with high or low scores determining different results.

True Response Inconsistency (TRIN): Pairs of opposites with high endorsement suggesting a tendency toward true responses indiscriminately on the exam.

Trull, T. (2005). Clinical Psychology, 7^th Edition. Belmont, CA. Thomson Wadsworth.