The Minnesota Multiphasic Personality Inventory, developed in the first version in the late '30s by Hathaway and McKinley and published in 1940, and its successor the MMPI-2 of 1989, edited by Butcher, Dahlstrom, Graham, Tellegen, is certainly the most used structured personality test in the world, adopted in at least 45 countries, with a bibliography of thousands of titles and a sound empirical basis.
The version of 1989 includes 567 items expressed as statements about themselves, concerning attitudes, interests, psychological characteristics, habits, beliefs, somatic complaints, aspirations, general considerations that the subject must sign as True or False, or 'do not know', selected from more than a thousand items from which they were eliminated those redundant or of little significance; for the American edition it is standardized on a sample of 2300 subjects, who are very representative of the total US population.
The different items groupings allow to build thirteen basic scales: three validity scales, L (lie), F (infrequency), and K (correction) and 10 clinical scales, Hypochondriasis - Hs or scale (1), Depression-D or scale (2), Hysteria -Hy or (3), Psychopathic deviate -Pd or (4), Masculinity-Femininity -MF or (5), Paranoia -PA (6), Psychasthenia -Pt (7), Schizophrenia -Sc (8), Hypomania -Ma or (9) and Social Introversion or -Si (0)).
Furthermore, there are fifteen supplemental scales, including three new Control Scales, Back F or FB (infrequency in the latter part of the protocol, over item no 370) and VRIN and TRIN (respectively, variable response Inconsistency, and true response inconsistency), twelve Scales related to specific issues (e.g., A- Anxiety, R- Repression, OH- Over-Controlled Hostility, MAC R- MacAndrews Alcoholism Scale Revised, PK and PS, for Post-traumatic Stress Disorder) and fifteen content scales, grouping similar areas (for example, ANX-Anguish, FRS-Phobias, HEA-Health Problems, LSE-Low Self-Esteem, FAM- Family Problems).
The process of construction of each basic scale was strictly empirical: for each clinical scale they choose a item group to which the group used as a criterion for that specific pathological feature (which selected with patients diagnosed with a single disturbance in order to avoid overlapping diagnostic) responded very differently from the control group of normal subjects.
The raw scores obtained for each scale are converted into linear T scores through the application of a formula that takes into account the raw scores mean and standard deviation for each normative group. Scores of some clinical scales are converted into linear T scores with K correction, taking into account the subject’s defensive attitude, expressed by the scale K.
To better define and specify the elevation of each Clinical scale, subscales were elaborated (Harris and Lingoes, 1968) which allow to better discriminate which specific psychological variables determine the elevation of the scale: for example, the D scale (Depression) may be high due to several factors: D1 Subjective Depression, D2, Psychomotor Retardation, D3 Physical Malfunctioning, D4 Mental Dullness, D5 Brooding, while the Pa Scale (Paranoia) can have an elevation due to factors described from subscales Pa1 Persecutory Ideas, Pa2 Poignancy, Pa3 Naiveté.
Moreover, two lists of critical items were developed, Koss and Butcher Critical items and Lachar and Wrobel Critical Items to identify specific problems: for example, Depressed Suicidal Ideation or Acute Anxiety State or Persecutory Ideas among the former and Problematic Anger and Deviant Thinking and Experience, Sleep Disturbances, among others.
Having recognized the protocol as a valid and reliable one, the analysis continues through the dedicated scales, with the interpretation based on per code interpretation (in case of emergence of a significant elevation of one or two scales compared to the rest of the profile), that is specified by comparing the actual scores reported by the subject and the average scores reported by the subjects with the same code type: considerable discrepancies and peculiarities of the responses are analyzed; the elevation of the clinical scales can be better explained through the interpretation of the relevant subscales, and supplemental and content scales. If you cannot find a defined code, the interpretation directly analyzes the various scales: clinics, additional content.
the Structural Summary is a very useful and interesting tool developed by Green and Nichols, grouping the different indices from the protocol in significant clusters (following the model of the Structural Summary of the Comprehensive System for the Rorschach test), so as to avoid overlap and redundancies, and it manages data in order to facilitate interpretation for areas: reliability, mood, cognitive activities, interpersonal relationships, other areas.
A true revolution in the test interpretation was introduced by the brilliant American scholar Alex Cadwell and eventually by other authors who followed him (Levak, Friedman, Finn) who placed the emphasis on the central role of the patient and of the interpretation of the different profiles and typical code types as an expression of specific adaptation modes - more or less effective or maladaptive- of the person to certain types of trauma or non-specific difficulties in the age of development.
This very innovative reading uses the analysis of the scales and of their traditional groupings to overcome the classic very impersonal 'descriptors' used by more classical authors, sometimes covertly “judgmental”, to obtain an empathic description and that understands the subject’s adaptation mechanisms to traumatic events and defense mechanisms.