The Minnesota Multiphasic Personality Inventory (MMPI) is the most common psychometric test devised to assess personality traits and psychopathology. This data can be used to draw conclusions about the test taker’s psychopathy or to interpret psychological characteristics compared to the norm.[1] The most common treatment application of the test by providers functions in establishing or reevaluating care for an ambiguous clinical picture.[2] For psychiatric management, this aids in creating generalizable data relevant to a plethora of possible conditions.[1][2]

The MMPI was developed in the 1930s and published through the University of Minnesota in 1942 by Stuart Hathaway and Charley McKinley using visitors of patients at the University of Minnesota hospital as a base sample in both theorizing constructs of psychiatric illness and fielding the instrument. Testing is administered through 567 true or false items using a booklet with an accompanying answer sheet. The responses are then hand-scored and plotted on an X-Y graph, a separate version being used for male and female respondents.[3] 

The X-axis is comprised of 14 scales. The first four ‘content scales’ judge validity of the test attempt and include: 

• ? to represent the number of questions completed incorrectly, either with no attempt or both ‘true’ and ‘false’ selected
• L for ‘Lie’ to represent an attempt by the respondent to misrepresent themselves in a more positive light 
• F or ‘frequency’ to gauge random response as well as the respondent’s exaggeration or downplaying of symptoms
• K to gauge ‘defensiveness,’ or evasion of stressful content 

The 10 remaining scales known as ‘clinical scales’ are designed to measure for the presence of psychiatric syndromes, including:

• 1 or ‘Hs’ for hypochondriasis
• 2 or ‘D’ for depression
• 3 or ‘Hy’ for hysteria
• 4 or ‘Pd’ for psychopathic deviate
• 5 or ‘Mf’ for the continuum of masculinity-femininity
• 6 or ‘Pa’ for paranoia
• 7 or ‘Pt’ for psychasthenia or obsessive-compulsive tendency
• 8 or ‘Sc’ for schizophrenia
• 9 or ‘Ma’ for mania
• 0 or ‘Si’ for social introversion.

The Y-axis statistically standardizes the grading received on each scale in a range of T-scores from 0 to 120. A mean score is 50, and 82% of respondents are considered to be the normal population falling between 30 and 70. A T-score greater than 70 indicates psychopathy in that category.

The existence of the MMPI has been concurrent with vast reforms in societal convention and increased understanding of behavioral health.[3] Likewise, the instrument has been adapted to reflect such changes. Overarching criticisms to the original test center on its disparity in addressing psychopathy in social and ethnic minorities.[1] This has been attributed to the original sample being a small group, mainly consisting of young rural Caucasian subjects from the Midwestern United States.[4] Studies have established biases in which misunderstanding or failure to culturally identify with the content of questions have led to underreporting or overreporting of mental illness.[5][1] 

These shortcomings led to the release of the MMPI-2 by James N. Butcher, W. Grant Dahlstrom, John R. Graham, Auke Tellegen, and Beverly Kaemme in 1989.[6] This assessment retains the original total of 567 items with the same corresponding 14 scales with the original number of questions from the test.[6] Test items were revised based upon a larger and more diverse sample size of 2600 attuned to a 6th-grade reading level.[6] Gendered differences were replaced with a nongendered standardized scoring.[6] Despite further advancements, the MMPI-2 is still the most commonly administered version and has been translated into over 40 languages.[1]

In 2003, 9 restructured clinical or ‘RC’ scales were introduced as a prospective replacement for the original clinical scales.[1] These include:

• RCd, or ‘demoralization’ – misery or depression
• RC1 or ‘somatic complaints, – the fixation on bodily symptoms of illness or somatization
• RC2 or ‘low positive emotions’ – weakened positivity, lack of enjoyment
• RC3 or ‘cynicism’ – low regard for the merit of others and their actions
• RC4 or ‘antisocial behavior’ – selfish and sociopathic conduct
• RC6 or ‘ideas of persecution’ – belief in the malintent of others toward oneself
• RC7 or ‘dysfunctional negative emotions’ – experiences on a spectrum of anxiety and irritability 
• RC8 or ‘aberrant experiences’ – uncommon beliefs or interpretation of experiences
• RC9 or ‘hypomanic activation’ – energetic drive and desire for exertion

The RC scales were devised to provide a streamlined interpretation and less overlap with an increased focus on the growth in understanding within psychiatry over the past 70 years. Combinations of high-scoring categories are more representative of distinct psychiatric constructs rather than the nebulous findings of the original clinical scales tying the patient to a specific diagnosis. Arguments also exist that this information is limited in that it categorizes the responder rather than providing data on an individual patient within a personalized spectrum of behavior.[1]

The RC scales have been incorporated into the most current form of the MMPI, which is known as the Minnesota Multiphasic Personality Inventory-2 Revised Form, or the MMPI-2-RF, which was released in 2008 by Yossef Ben-Porath and Auke Telleger of the University of Minnesota. The MMPI-2-RF is composed of 338 items measured by 51 scales broken into 9 validity scales, 3 higher-order scales, the 9 RC scales, 23 specific problem scales, 2 interest scales, and 5 revised personality psychopathy scales.[1]

The 9 validity scales assess incongruent answering or deceptive test-taking and include:

• VRIN-r or ‘variable response inconsistency’ – inconsistent reporting of items
• TRIN-r or ‘true response inconsistency’ careless reporting of items
• F-r or ‘infrequent responses,’ – overreporting of infrequent responses compared to the norm
• Fp-r or ‘infrequent psychopathology responses’ – overreporting of infrequent responses compared to those with psychopathy
• Fs or ‘infrequent somatic responses’ – overreporting of infrequent responses compared to medical patients
• FBS-r or ‘symptom validity’ – overreporting of nonvalid symptoms compared to both physical and mental standard symptomology
• RBS or ‘response bias’ – overreporting associated with a statistically invalidated presentation of the disease
• L-r or ‘uncommon virtues’ – underreporting through infrequently declared values or actions
• K-r or ‘adjustment validity’ – underreporting by tailoring answers to give the impression of healthy psychological adjustment 

The 3 higher-order scales broadly categorize psychopathic presentation and include:

• EID or ‘emotional/internalizing dysfunction’ – problems concerning mood and affect
• THD or ‘thought dysfunction’ – problems concerning disorganization of thought
• BXD or ‘behavioral/external dysfunction’ – problems concerning impulsive or inappropriate behavior 

The problem scales highlight responses consistent with the presence of specific psychopathic and psychosomatic presentations and include:

• MLS or ‘malaise’
• GIC or ‘gastrointestinal complaints’
• HPC or ‘head pain complaints’
• NUC or ‘neurological complaints’
• COG or ‘cognitive complaints’
• SUI or ‘suicidal/death ideation’
• HLP or ‘helplessness/hopelessness’
• SFD or ‘self-doubt’
• NFC or ‘inefficacy’
• STW or ‘stress/worry’
• AXY or ‘anxiety’
• ANP or ‘anger proneness’
• BRF or ‘behavior-restricting fears’
• MSF or ‘multiple specific fears’
• JCP or ‘juvenile conduct problems’
• SUB or ‘substance abuse’
• AGG or ‘aggression’
• ACT or ‘activation’
• FML or ‘family problems’
• IPP or ‘interpersonal passivity’
• SAV or ‘social avoidance’
• SHY or ‘shyness’
• DSF or ‘disaffiliativeness’ 

The interest scales are designed to assess cognitive skills aptitude and learning preferences which include:

• AES or aesthetic-literary interests – pursuits related to fine art
• MEC or mechanical-physical interests – pursuits related to kinesthetic activities

The revised personality/psychopathology five scales are based on 107 distinct items and include:

• AGG-r or ‘aggressiveness-revised’ – preference for excess and antagonism
• PSYCH-r or ‘psychoticism-revised’ – preference for disconnection from reality
• DISC-r or ‘disconstraint-revised’ – preference for impulsion and compulsion
• NEGE-r or ‘negative emotionality/neuroticism-revised’ – preference for anxiety
• INTR-r or ‘introversion/low positive emotional-revised’ – flat affect and timidity

It has been suggested that while the MMPI-2-RF has many additional metrics, the reduction in question number limits the amount of information about psychiatric diseases to about 60% of the original test. There has also been considerable debate over whether the new metrics are inaccurate in detecting psychopathy.[1] In separating genuine psychopathy from attempts to feign a diagnosis for personal incentive, some studies have noted the new validity scales to be overly sensitive to overreporting of symptoms to achieve a specific result. It has conversely been found that the L-r and K-r scales are particularly reliable at detecting underreporting of mental illness.[7][8] Overall, literature has been supportive of the MMPI-2-RF in identifying the accuracy of reporting psychiatric information in those who complete it.[1]

The MMPI maintains an enduring presence in the field of mental health, and its current adaption has been widely evaluated by the standard of modern behavioral health practices.[1] It continues to receive a widespread application as a threshold of determining the presence of psychopathy, as a means of constructing a differential diagnosis for mental health problems, and as a versatile test to achieve transferrable psychological data. These data points are themselves the indication of a category, and this gives behavioral health professionals a starting point to explore plausible diagnoses and initiate appropriate treatment. Completion may also offer therapeutic benefits to patients in reflecting upon their issues and improving personal understanding of their psychology.[3]

In addition to its predominant clinical application, an extensive body of research exists to assess the MMPI in all its versions for the use in criminology, population studies, and prediction of aptitude in a particular role. Several studies on the MMPI-2-RF have compared those with a criminal history to those who have undergone rehabilitation and found that high scores on externalizing scales were predictive of violent behavior.[9] The MMPI-2-RF has also been used as prescreening of applicants for law enforcement for obtaining baseline mental health or flagging for aggressive tendencies.[1][10] There has also been usage evaluating parenting suitability in custody battles over children, and in predicting the course of domestic disputes in couples.[11][12] Interpretations of the test have also been used to establish criminal intent in defendants.[1][9]

A major consensus of the MMPI in its current form is that increased accessibility for being tested improves retention without compromising outcomes. Prevailing criticisms of the original format were the extensive span of questioning and difficulty of paper administration for both completion and grading, with efforts to provide a more efficient medium well-documented since the 1980s.[13] When evaluating the use of tablet devices as compared to conventional forms of electronic administration using a home computer or laptop for taking the MMPI-RF-2, the difference in reliability of results between the two mediums was insignificant.[14] There have also been motions to use the MMPI-2-RF to assess psychopathy utilizing an algorithm using a high score on a higher-order scale and then tailoring the remaining assessment to similar questions to the indicated higher order.[15] To aid in administration to pediatric patients, an adolescent form exists known as the Minnesota Multiphasic Personality Inventory-Adolescent-Restructured Form (MMPI-A-RF).[16] 

Clinical Pearls: 

• The MMPI provides broad information about aspects of personality and the existence of components of psychopathology.
• The MMPI is completed by indicating true/false to a series of declarative statements that identify personal beliefs or symptomology.
• Interpretation is based upon scoring reasonably truthfully and consistently within the outlined scales of the test.
• Scales in older versions represented clinical syndromes, while more recently developed scales are based on identifying symptoms that can be applied to appropriate conditions or disorders.
• The MMPI is effective at distinguishing psychopathy from malingering or purposeful test-taking as well as from medical conditions.
• The MMPI has been revised to make the test more efficient, reproducible to test-takers in a broader societal demographic, and more grounded in current theory.
• The MMPI can be taken by an individual patient to provide evidence of their symptoms but can also be fielded to a population fitting a known category to observe trends within their scoring.
• The MMPI has been applied to a variety of non-clinical settings, including legal evidence in criminal and civil cases as well as screening for employment.

The completion of the MMPI holds value in determining care throughout a variety of treatment considerations. The test should be administered by a licensed psychotherapist, usually a psychiatrist or clinical psychologist, with informed consent obtained through discussion of the risks and benefits of completion. Analysis of the results by the psychotherapist interpreting scoring should be attached with a working diagnosis to assess for treatment response. The presence of conditions associated with high-scoring categories will ultimately guide the necessity for pharmacological or non-pharmacological treatment options. This will, in turn, outline the need for referral to appropriate mental healthcare, from continuing outpatient follow-up to institutionalization with fully-staffed nursing and rehabilitative care. Transfer of care should involve appropriate discussion of MMPI data correlated with a summary of interventions. High-scoring in concerning scales such as suicidality highlights an existing need for acute observation or placement. The validity of symptoms should also be corroborated to demonstrate whether a patient is malingering or suffering from organic disorders requiring medical management by a treatment team. The bio-ethical implications of the MMPI should also be identified if the patient is completing the test in concurrence or stipulation with legal charges, and they should be counseled on what findings might hold concerning criminality. The basis for the use of test data in determining adherence has also been documented in a sample consisting of 471 psychiatric patients, with externalizing scales predictive of whether a patient will be more likely to terminate treatment.[1] [Level 3] This illustrates the need for multi-level involvement in facilitating outreach and patient compliance.