Religious Fundamentalism Scale

Abstract

The Religious Fundamentalism Scale (REL) is one of the 13 substantive content scales developed by Jerry S. Wiggins (1966) for the original Minnesota Multiphasic Personality Inventory (MMPI; Hathaway & McKinley, 1951). Constructed through a rigorous combination of rational item selection and empirical psychometric refinement, the REL scale was designed to measure manifest self-reports of orthodox religious beliefs, biblical literalism, and religiously guided lifestyle practices. The instrument comprises 12 dichotomous (True/False) items embedded within the standard 566-item MMPI pool. Eleven items are keyed for “True” responses indicating agreement with orthodox Christian theology, divine intervention, eschatological beliefs, and regular devotional habits, while one item is reverse-keyed (“False”) tapping intolerance toward exclusive religious claims. Psychometrically, the REL scale demonstrates superior internal consistency relative to many standard clinical MMPI scales, with Cronbach’s alpha coefficients typically ranging from .67 to .89 across military and collegiate populations, and six-week test-retest reliability estimates exceeding .93. Factor analytic and construct validation research demonstrates that REL loads on broader dimensions of impulse control versus behavioral acting out, correlating negatively with substance abuse, psychopathy, and sensation seeking, but displaying modest positive associations with delusional thinking and cognitive rigidity in select psychiatric cohorts. Following the restructuring of the MMPI into the MMPI-2 in 1989, the Wiggins content scales—including the REL—were officially retired in favor of the Butcher et al. content scales, rendering the REL scale a historically seminal tool in personality assessment, religious psychology, and the psychometric evolution of self-report inventories.

Keywords

Religious Fundamentalism Scale, Wiggins Content Scales, MMPI, Minnesota Multiphasic Personality Inventory, Jerry S. Wiggins, Religious Orthodoxy, Intrinsic Religiosity, Psychometrics, Test-Retest Reliability, Construct Validity, Self-Report Inventory, Clinical Assessment

Authors

The Religious Fundamentalism Scale (REL) was developed by Jerry S. Wiggins, Ph.D. (1931–2006), a distinguished clinical psychologist and prominent psychometrician renowned for his pioneering work in interpersonal assessment, personality structure, and scale construction methodology. Wiggins completed his doctoral training in clinical psychology at Indiana University and served on the faculties of the University of Illinois at Urbana-Champaign and the University of British Columbia. His developmental work on the MMPI content scales took place predominantly during his tenure at the University of Illinois.

The parent instrument from which the REL scale items were drawn was created by Starke R. Hathaway, Ph.D., and J. Charnley McKinley, M.D., at the University of Minnesota Hospitals, originally published in 1943 by the University of Minnesota Press and subsequently distributed by The Psychological Corporation.

Purpose

The primary purpose of the Religious Fundamentalism Scale was to provide an objective, internally homogeneous measure of overt religious attitudes and behaviors from the standard MMPI item pool. When the MMPI was initially formulated in the late 1930s and 1940s, Hathaway and McKinley utilized an empirical criterion keying methodology. Under this paradigm, items were selected for clinical scales (e.g., Scale 1 [Hypochondriasis], Scale 2 [Depression], Scale 4 [Psychopathic Deviate]) solely because they differentiated a specific clinical psychiatric group from a normative group of “Minnesota normals,” regardless of the manifest semantic content of the items. Consequently, the original MMPI clinical scales were characterized by high item overlap, multidimensionality, and ambiguous face validity.

In response to growing clinical and research demands for interpretable, face-valid assessment dimensions, Wiggins (1966) sought to construct mutually exclusive, internally consistent scales that reflected the actual manifest content of test-takers’ self-descriptions. The REL scale was specifically developed to measure self-reported fundamentalist religious convictions, theological orthodoxy, personal devotional behavior, and institutional religious involvement. Crucially, Wiggins emphasized that the term “fundamentalism” within this psychometric context was not intended as a sociological or political pejorative, nor was it tied to any specific denomination; rather, it captured an adherence to orthodox Judeo-Christian tenets and traditional moral frameworks.

In clinical practice, the REL scale was utilized to clarify the meaning of elevations on conventional clinical scales. For example, religious ideation in psychiatric patients can either reflect intact spiritual coping mechanisms or, alternatively, somatic/religious delusions and severe obsessive-compulsive scrupulosity. The REL scale allowed clinicians to determine whether religious content represented an integrated, socially normative system of fundamentalist belief or idiosyncratic psychopathology. Furthermore, high REL scores frequently provided explanatory context for low scores on externalizing pathology, indicating patients who rely heavily on religious dogma and moral rules to regulate impulses, mitigate family conflict, and abstain from substance abuse.

In research contexts, the scale served as a prominent operationalization of religious orthodoxy and social conservatism within broader personality inventories. It facilitated investigations into the behavioral correlates of dogmatism, authoritarianism, ego development, and the structural relationship between religious values and personality pathology.

Psychological Construct

The construct assessed by the Religious Fundamentalism Scale reflects manifest, highly structured orthodox religious devotion and theological conservatism. Within the psychometric architecture of the MMPI, Wiggins established the REL scale to measure an individual’s explicit self-identification as a deeply devout, observant believer who subscribes to classical scriptural doctrines. Rather than measuring mystical experiences or diffuse spiritual inclinations, the REL construct is grounded in identifiable cognitive, behavioral, and doctrinal facets.

Doctrinal Orthodoxy and Eschatological Belief

A core dimension of the REL construct is belief in supernatural theological tenets characteristic of traditional Christian theology. This includes literal acceptance of biblical prophecy (“Everything is turning out just like the prophets of the Bible said it would”), belief in the bodily second coming of Jesus Christ, affirming the reality of an afterlife, and the historical reality of biblical miracles (such as turning water into wine). High scorers exhibit unambiguous cognitive assent to the existence of God, Heaven, a personal Devil, and Hell as a physical or metaphysical reality of divine judgment.

Religious Exclusivism

The construct encompasses theological particularism or religious exclusivism—the conviction that one’s specific faith represents the singular pathway to divine truth and salvation (“I feel sure that there is only one true religion”). Conversely, low scorers reject this theological exclusivity, endorsing items indicating tolerance or patience toward alternative, divergent religious systems. Notably, high REL scores capture a cognitive style characterized by ideological certainty, doctrinal rigidity, and a rejection of theological relativism.

Institutional and Personal Devotional Practice

Beyond abstract theological assent, the REL scale measures concrete, behavioral manifestations of faith. These include habitual participation in institutional worship services (“I go to church almost every week”) and private devotional routines, such as daily or weekly Scripture reading and regular personal prayer. Individuals who score highly on the scale overtly perceive themselves as substantially more religious than the average population, viewing their daily functioning through a lens of moral accountability and pious commitment.

Behavioral and Psychological Correlates

The psychological profile associated with high REL scores varies significantly across functional settings. In normative and non-clinical samples, elevations correspond to conscientiousness, strong pro-social conformity, adherence to conventional morality, and minimal engagement in externalizing behaviors such as drug use, excessive alcohol consumption, and delinquent rebellion. However, within clinical psychiatric settings, markedly elevated REL scores frequently correspond to cognitive inflexibility, punitive superego introjects, scrupulosity, and, in severe cases, religious delusions or thought disorganization (Graham, 1987; Lachar & Alexander, 1978). Importantly, because the REL items measure manifest content, the scale does not inherently discriminate between flexible, mature intrinsic religiosity and rigid, defensive dogmatism; both manifestations can produce raw scores in the 10–12 range.

Theoretical Framework

The theoretical underpinning of the REL scale is rooted in the psychometric movement of the 1960s that championed substantive or rational-theoretical approaches to self-report personality assessment, directly challenging the uncritical hegemony of radical empirical criterion keying. The theoretical framework was heavily guided by Jerry S. Wiggins‘ perspective on the semantic properties of personality statements, alongside Gordon Allport’s classical contributions to the psychology of religion.

The Rational-Empirical Synthesis in Scale Construction

Wiggins argued that empirical criterion keying, while historically beneficial for psychiatric screening, produced clinical scales burdened by heterogeneous item content, poor internal consistency, and substantial vulnerability to criterion contamination. Drawing on the psychometric principles articulated by Loevinger (1957) and Jackson (1970), Wiggins posited that self-report personality items possess clear communicative value. When an individual completes an MMPI protocol, their responses constitute manifest communications regarding their self-concept, social attitudes, and experiential world.

Wiggins established that content dimensions should be derived through a sequential strategy: first, establishing face-valid substantive categories through rational expert consensus; second, utilizing internal consistency metrics to ensure item-total homogeneity; and third, enforcing statistical independence between scales by eliminating overlapping items. The REL scale emerged from this methodology as the primary operational representation of the MMPI’s substantive religious domain.

Integration with Psychological Theories of Religion

Thematically, the REL scale aligns with Gordon Allport‘s conceptualization of religious orientation, particularly the distinction between intrinsic religiosity (faith as a master motive and internalized guiding framework) and orthodox doctrinal adherence. While Allport and Ross (1967) highlighted the danger of institutionalized religion fostering prejudice, subsequent empirical work demonstrated that traditional religious adherence operates as a complex self-regulatory system. Within psychodynamic and social cognitive frameworks, fundamentalist religious beliefs provide external and internalized rule architectures that enhance behavioral control, diminish existential ambiguity, and supply coherent explanatory narratives for distressing life events.

Validity

The construct, convergent, and discriminant validity of the Wiggins Religious Fundamentalism Scale has been documented across normative, collegiate, military, and psychiatric samples.

Convergent and Discriminant Validity

Convergent validity was demonstrated by Taylor et al. (1972) in a comprehensive investigation of self-judgments and personality scales. The REL scale correlated strongly (r = .83) with the Religious Orientations Scale of the Omnibus Personality Inventory (OPI), which independently assesses adherence to conventional religious beliefs and practices. Taylor and colleagues also administered two direct, anchored self-rating scales evaluating religious fundamentalism (e.g., self-appraisal ranging from “strongly religious in a fundamentalist sense” to “not very religious in a fundamentalist sense”); these anchored rating questions correlated .759 and .774 with the REL scale, confirming that the scale accurately captures test-takers’ conscious, explicit identification with religious fundamentalism.

Discriminant validity analyses reveal that REL measures a distinct psychological dimension that is largely absent from traditional personality inventories. Wiggins, Goldberg, and Applebaum (1971) found that REL yielded minimal and negligible correlations with scales from the California Psychological Inventory (CPI), the Adjective Check List (ACL), and the Edwards Personal Preference Schedule (EPPS). Furthermore, REL demonstrates minimal overlap with the standard MMPI clinical scales. In the Wiggins et al. (1971) normative sample, correlations between REL and standard clinical scales tapping acute distress and behavioral deviance were consistently low to moderately negative:

• Scale F (Infrequency / Distress): r = -.26
• Scale 2 (Depression): r = -.17
• Scale 4 (Psychopathic Deviate): r = -.14
• Scale 9 (Hypomania / Impulsivity): r = -.15

The scale also shows modest demographic relationships, exhibiting slight positive correlations with chronological age and slight negative correlations with educational attainment (Colligan & Offord, 1988).

Criterion and Factorial Validity in Clinical Settings

In his 1966 monograph, Wiggins performed discriminant analyses across various psychiatric diagnostic groups, discovering that the REL scale alone did not reliably differentiate between broad psychiatric classifications (e.g., schizophrenia versus affective disorders). This finding reinforced the conceptualization of religiosity as a normative dimensional value system rather than an index of clinical illness. However, Hoffman and Jackson (1976) evaluated the factor structure of the MMPI content scales combined with the Differential Personality Inventory in a large psychiatric cohort. REL loaded heavily on an orthogonal dimension designated as “Impulse Expression versus Religiosity,” displaying strong negative loadings on rebelliousness, acting-out, and sociopathic deviance.

Similarly, Lachar and Alexander (1978) demonstrated that psychiatric inpatients with elevated REL scores exhibited significantly reduced frequencies of illicit substance abuse, antisocial acting-out, and interpersonal hostility. However, when highly elevated in severely decompensated patients, high REL scores were paradoxically accompanied by increased ratings of conceptual disorganization and delusional content, indicating that underlying thought disorder may be filtered through orthodox religious themes.

Reliability

Despite consisting of only 12 items, the REL scale consistently exhibits the highest internal consistency and temporal stability among all 13 Wiggins MMPI content scales.

Internal Consistency

Wiggins (1966) reported coefficient alpha values for REL across multiple distinct cohorts during initial scale development:

• U.S. Air Force Basic Airmen (N = 261): Cronbach’s alpha = .67
• University of Illinois Male Undergraduates (N = 291): Cronbach’s alpha = .82 to .89 across sub-samples
• University of Illinois Female Undergraduates (N = 203): Cronbach’s alpha = .76 to .86 across sub-samples

Subsequent psychometric evaluations by Taylor et al. (1972) and Jamecke and Chambers (1977) confirmed alpha coefficients consistently clustering around .80 to .88 in collegiate and general medical populations. The psychometric homogeneity of the scale is directly attributable to the strict empirical inclusion threshold enforced by Wiggins, requiring every item to correlate substantially with the total scale score while demonstrating lower correlations with all other 12 content scales.

Test-Retest Stability

The REL scale demonstrates exceptional temporal stability over time. In a retest investigation conducted by Wiggins (1966) involving 203 university students over a six-week interval, the test-retest reliability coefficient was r = .95 for men and r = .93 for women. These figures represent the highest stability coefficients observed across the Wiggins content scale battery, indicating that manifest religious attitudes and fundamentalist values represent stable, enduring traits of the adult self-concept.

Factor Analysis

The construction and subsequent validation of the Religious Fundamentalism Scale relied heavily on factor-analytic and correlational matrix procedures.

Wiggins’ Constructional Matrix Analysis

Wiggins initiated scale development by reviewing the MMPI’s original 26 content categories established by Hathaway and McKinley. He grouped items into substantive thematic clusters, isolating a candidate pool of items concerning religious attitudes. To establish scale boundaries, Wiggins computed item-to-scale and item-to-other-scale correlation matrices across military, student, and clinical cohorts. The empirical inclusion criteria were strictly defined:

1. The item had to achieve a point-biserial correlation with its designated content scale of r ≥ .30.
2. The item’s correlation with its own scale had to unequivocally exceed its correlation with every other content scale in the battery.

This rigorous mathematical purification resulted in a completely mutually exclusive 13-scale structure with zero item overlap. The 12 items that survived this filter formed a unidimensional, highly cohesive factor capturing fundamentalist beliefs and religious observance.

Higher-Order Factor Structure

Subsequent exploratory factor analyses (EFA) of the 13 Wiggins content scales have consistently isolated REL as an independent, distinct higher-order dimension. Wiggins (1969) examined the factor structure of the content scales in collegiate and clinical samples, consistently extracting four or five major dimensions. While scales such as Depression (DEP), Anxiety (ANX), and Poor Morale (MOR) collapsed onto a broad “Internalizing / Neurotic Distress” factor, and scales like Hostility (HOS) and Hypomania (HYP) loaded onto “Externalizing / Impulse Control” dimensions, the REL scale consistently loaded uniquely on its own factor or stood as the polar opposite anchor of an “Amoral Delinquency versus Pious Orthodoxy” factor.

In a large-scale factor analysis conducted by Hoffman and Jackson (1976) involving 1,188 psychiatric patients, principal component analysis with varimax rotation revealed that REL loaded .78 on a dedicated “Religiosity vs. Behavioral Deviance” factor. Confirmatory studies by Jamecke and Chambers (1977) corroborated that REL exhibits minimal cross-loadings on somatic distress, social alienation, or psychotic disorganization factors, underscoring its functional independence within the MMPI item pool.

Instrument / Measurement Tool

The Religious Fundamentalism Scale is an embedded self-report content inventory derived from the original MMPI item inventory. Key structural and administrative characteristics include:

• Test Type: Objective, self-report personality content scale.
• Parent Inventory: Minnesota Multiphasic Personality Inventory (MMPI; original 566-item form).
• Item Count: 12 items.
• Administration Format: Paper-and-pencil booklet, optical scan sheet, or computerized MMPI administration.
• Estimated Time: Approximately 2 to 4 minutes when completed as a standalone subset; 60 to 90 minutes when administered within the complete 566-item MMPI.
• Target Population: Adolescents (aged 16+) and adults possessing at least a sixth-grade reading level.
• Response Format: Dichotomous forced-choice (True / False).
• Scoring and Directionality:
  • Raw scores range from 0 to 12.
  • 11 items are keyed True: Endorsement yields 1 point each (Items corresponding to MMPI numbers: 95, 98, 115, 206, 220, 249, 258, 483, 488, 490, and equivalent).
  • 1 item is keyed False: Endorsement of “False” yields 1 point (Item 12 / MMPI Item 491: “I have no patience with people who believe there is only one true religion”).
  • Higher raw scores indicate greater religious fundamentalism, theological orthodoxy, and overt devotional practice.
• Clinical Standardization and T-Scores: Raw scores are converted to linear T-scores (Mean = 50, Standard Deviation = 10) based on normative reference tables (e.g., Hathaway & Briggs, 1957; Wiggins et al., 1971; Colligan & Offord, 1988). A T-score ≥ 70 (+2 SD) represents clinically significant elevation, whereas a T-score ≤ 40 indicates low religiosity / non-fundamentalist attitudes.
• Validity / Correction Mechanisms: Unlike the standard MMPI clinical scales, the REL scale does not incorporate a K-correction factor for social desirability or defensiveness. Clinicians are advised to evaluate the standard validity indicators (L, F, K) to identify self-favorableness or random responding.

Permissions & Fee and Test Year

The Religious Fundamentalism Scale was officially introduced in 1966 through Jerry S. Wiggins’ landmark monograph published in Psychological Monographs: General and Applied. The individual items comprising the scale are proprietary elements of the original Minnesota Multiphasic Personality Inventory, copyrighted by the University of Minnesota and originally distributed commercially by The Psychological Corporation (now Pearson Clinical Assessment).

Current Status and Obsolescence: During the major restandardization that culminated in the release of the MMPI-2 in 1989 (Butcher et al., 1989), the Wiggins content scales were systematically phased out. Psychometricians developing the MMPI-2 formulated a new set of 15 content scales (Butcher, Graham, Williams, & Ben-Porath, 1990). In this revision, 11 of the 12 Wiggins REL items were deleted or reworded to modernize the test pool, leaving only one original REL item in the MMPI-2 instrument (Kohutek, 1992). Consequently, the Wiggins REL scale cannot be scored or calculated from MMPI-2 or MMPI-3 protocols.

The scale remains accessible in historical psychometric literature for scholarly, academic, and non-commercial research purposes. Researchers wishing to administer the full original MMPI item pool must consult the University of Minnesota Press regarding contemporary copyright policies, licensing permissions, and archival access fees.

References

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• Caldwell, A. B. (1988). MMPI supplemental scale manual. Caldwell Report.
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• Wiggins, J. S., Goldberg, L. R., & Applebaum, M. (1971). MMPI content scales: Interpretive norms and correlations with other scales. Journal of Consulting and Clinical Psychology, 37(3), 403–410. https://doi.org/10.1037/h0032014

Items of the Scale