Trust (General) (TRU)

Abstract

The Trust (General) (TRU) scale is a specialized psychometric subscale embedded within the widely recognized Perceived Relationship Quality Components (PRQC) inventory, initially developed and validated by social psychologists Garth J. O. Fletcher, Jeffrey A. Simpson, and Geoff Thomas in 2000. Formulated to address conceptual and empirical ambiguities inherent in earlier relationship assessment instruments, the TRU scale quantifies an individual’s perceived dependability on and subjective confidence in their romantic partner. Comprising three carefully calibrated items, the instrument uses a 7-point Likert-type response format ranging from 1 (“Not at all”) to 7 (“Extremely”). Psychometrically, the scale demonstrates robust internal consistency (with Cronbach’s alpha values typically ranging between .85 and .91 across diverse adult relationship cohorts), exceptional factor determinacy, and high factor loadings (> .80) within both first-order and higher-order confirmatory factor analytic frameworks. In addition to establishing strong construct and convergent validity alongside established instruments such as the Dyadic Trust Scale and the Investment Model Scale, the TRU scale exhibits clear discriminant validity from adjacent constructs such as commitment, intimacy, passion, and general relationship satisfaction. The scale’s brevity, low respondent burden, and solid theoretical foundations make it a gold-standard instrument in empirical relationship science, dyadic health psychology, and clinical couples therapy evaluations.

Keywords

Interpersonal trust, Perceived Relationship Quality Components, PRQC, Garth Fletcher, Jeffrey Simpson, relationship satisfaction, dyadic dependability, close relationships, romantic attachment, psychometrics, scale validation, confirmatory factor analysis

Authors

The Trust (General) (TRU) scale was formulated by prominent scholars in social psychology and close relationships research:

• Garth J. O. Fletcher, Ph.D.: Emeritus Professor of Psychology at the Victoria University of Wellington, New Zealand. Renowned internationally for his seminal contributions to the social cognition of romantic relationships, ideal standards models, and the evolutionary psychology of human mating.
• Jeffrey A. Simpson, Ph.D.: Professor of Psychology and Director of the Doctoral Program in Social Psychology at the University of Minnesota, United States. An authority on adult attachment, evolutionary social psychology, dyadic interaction processes, and trust development in interpersonal dyads.
• Geoff Thomas, Ph.D.: Researcher formerly affiliated with the Department of Psychology at the University of Canterbury, Christchurch, New Zealand, contributing methodologically to dyadic confirmatory factor modeling and psychometric instrument construction.

Purpose

The primary purpose of the Trust (General) (TRU) scale is to provide a brief, psychometrically rigorous, and theoretically unconfounded assessment of perceived interpersonal trust in adult romantic relationships. Prior to the development of the Perceived Relationship Quality Components (PRQC) framework by Fletcher and colleagues in 2000, relationship science faced significant methodological challenges. Dominant omnibus measurement tools—such as the Dyadic Adjustment Scale (DAS; Spanier, 1976) and the Marital Adjustment Test (MAT; Locke & Wallace, 1959)—conflated subjective evaluations of relationship quality with structural stability, communication frequencies, behavioral agreements, and conflict patterns. This confounding made it difficult to disentangle subjective perceptions (such as trust or love) from objective dyadic behaviors (such as time spent together or frequency of disagreements).

To overcome this limitation, Fletcher, Simpson, and Thomas (2000) systematically identified six fundamental components representing perceived relationship quality: satisfaction, commitment, intimacy, trust, passion, and love. The TRU subscale was designed to isolate the psychological dimension of trust: an individual’s firm confidence in the integrity, reliability, and emotional dependability of their partner. Measuring this construct in isolation is crucial for several clinical and research applications:

• Couples Therapy and Clinical Assessment: In clinical settings, trust serves as a bellwether for relationship distress, attachment insecurity, and interpersonal injury. Therapists utilizing Emotionally Focused Therapy (EFT) or Integrative Behavioral Couple Therapy (IBCT) can deploy the TRU subscale to evaluate baseline dyadic safety, monitor repair interventions following infidelity or breaches of confidence, and track longitudinal therapeutic progress.
• Dyadic Interaction and Conflict Research: In experimental and observational paradigms, baseline trust directly moderates emotional reactivity, cognitive attributions, and physiological stress responses (such as cortisol and vagal withdrawal) during conflict discussions. The 3-item TRU scale allows researchers to control for or directly examine trust without overburdening participants during multi-wave or daily diary protocols.
• Longitudinal Studies of Relationship Transitions: The scale enables researchers to track shifts in interpersonal faith during vulnerable transitions, including the transition to parenthood, cohabitation, major geographic relocation, or chronic health diagnoses.

Psychological Construct

Interpersonal trust in romantic dyads is defined as an individual’s confident expectation that their partner will act with benevolence, dependability, and supportive responsiveness, even when vulnerability or risk is present. The TRU subscale isolates three complementary dimensions of interpersonal trust, distilling them into a parsimonious three-item scale:

1. Global Evaluative Trust

Global trust represents an overarching, synthesized cognitive-affective appraisal of a partner’s benevolence and moral integrity (captured by the item: “How much do you trust your partner?”). This facet aligns with John Rempel, John Holmes, and Mark Zanna’s (1985) concept of “faith”—a psychological state transcending specific behavioral evidence. It reflects a secure conviction that the partner holds genuine concern for one’s welfare and will not intentionally inflict psychological or physical harm.

2. Behavioral Reliance and Contingency

Behavioral reliance focuses on the functional predictability of a partner’s responsiveness in times of need (captured by the item: “How much can you count on your partner?”). This dimension captures the partner’s perceived willingness to sacrifice self-interest to provide instrumental and emotional support during distressing, ambiguous, or demanding situations. It reflects the respondent’s willingness to depend on the partner when vulnerable.

3. Perceived Structural Dependability

Perceived dependability addresses the perceived stability, consistency, and fidelity of the partner’s character and actions over time (captured by the item: “How dependable is your partner?”). Unlike spontaneous responsiveness, dependability reflects habitual reliability, conscientiousness, and predictability in fulfilling relationship agreements, promises, and relational obligations.

By assessing these three dimensions, the TRU scale captures trust as a coherent psychological construct, cleanly separated from general relationship happiness, romantic passion, or structural barriers to leaving the partnership.

Theoretical Framework

The construction and validation of the TRU scale are grounded in two prominent theoretical paradigms in relationship science: Interdependence Theory and Adult Attachment Theory.

Interdependence Theory

Rooted in the social exchange principles formulated by Harold Kelley and John Thibaut (1978) and expanded in Caryl Rusbult’s (1980) Investment Model, Interdependence Theory posits that relationships are defined by how partners influence each other’s outcomes. In this framework, trust develops through repeated interactions characterized by non-zero-sum coordination and transformed motivation. When a partner sacrifices immediate personal desires to support the relationship (pro-relationship transformation of motivation), the other individual gains diagnostic evidence of their partner’s benevolent commitment.

Simpson (2007) formalized this process in the Dyadic Model of Trust, proposing that trust serves as a dynamic cognitive lens that buffers against vulnerability in diagnostic situations. The TRU scale assesses the psychological outcome of this ongoing assessment: an overarching judgment that the partner consistently chooses pro-relationship behaviors across interdependence dilemmas.

Adult Attachment Theory

Originating from John Bowlby‘s ethological framework and adapted for adult romantic contexts by Cindy Hazan and Phillip Shaver (1987), attachment theory posits that individuals develop internal working models of the self and others based on early caregiving interactions. In adult pair-bonds, trust represents the operationalized core of an attachment figure serving as a “safe haven” and “secure base.”

A high score on the TRU scale indicates that the partner is perceived as accessible, responsive, and emotionally safe—the hallmarks of attachment security. Conversely, low scores reflect attachment anxiety (doubts regarding the partner’s enduring care) or attachment avoidance (compulsive self-reliance and defensive dismissal of the partner’s dependability).

Validity

The TRU scale exhibits extensive construct, convergent, discriminant, and predictive validity across empirical investigations:

Construct and Factorial Validity

Fletcher, Simpson, and Thomas (2000) conducted extensive confirmatory factor analyses across multiple independent samples of university students and community adults in dating, cohabiting, and married relationships. First-order confirmatory factor models revealed that the three TRU items loaded substantially onto their designated trust latent factor (λ > .80), with standardized factor loadings frequently exceeding .85. These loadings confirmed that the items share substantial variance, indicating strong unidimensional construct validity.

Convergent Validity

The TRU scale demonstrates strong positive correlations with alternative, longer relationship measurement tools. Specifically, TRU scores correlate strongly with:

• The Dyadic Trust Scale (Larzelere & Huston, 1980; r = .70 to .82).
• The Trust Scale developed by Rempel, Holmes, and Zanna (1985; r = .68 to .78).
• The Investment Model Scale’s commitment and satisfaction dimensions (Rusbult, Martz, & Agnew, 1998; r = .60 to .75).

Discriminant Validity

Discriminant validity was established by comparing alternative nested CFA models (Fletcher et al., 2000). A single-factor model collapsing trust, satisfaction, commitment, intimacy, passion, and love resulted in poor fit (χ² difference tests indicated Δχ² values significant at p < .001 when moving from a single-factor to a six-factor model). Furthermore, the correlation between the latent trust factor and the latent passion factor was moderate (r ≈ .52), demonstrating that trust reflects a distinct cognitive-evaluative appraisal rather than mere physical attraction or emotional arousal.

Predictive and Criterion-Related Validity

Longitudinal studies demonstrate that baseline scores on the TRU subscale uniquely predict relationship stability over time, buffering couples against dissolution. For example, during observed dyadic conflict tasks, individuals with higher TRU scores engage in fewer destructive communication patterns (such as criticism, defensiveness, and contempt; Gottman, 1994) and show higher levels of constructive problem-solving and cognitive reframing.

Reliability

The TRU scale demonstrates high internal consistency and longitudinal stability despite its brief, three-item design:

Internal Consistency

In the original validation studies by Fletcher, Simpson, and Thomas (2000), internal consistency coefficients for the 3-item TRU scale were exceptionally strong:

• Study 1 (Dating Samples): Cronbach’s alpha (α) = .87
• Study 2 (Longitudinal Validation Sample): Cronbach’s alpha (α) = .89

Subsequent independent studies across diverse cultural contexts and relationship configurations have consistently confirmed these reliability metrics, with McDonald’s omega (ω) and Cronbach’s alpha values regularly falling between .85 and .92. Average inter-item correlations typically range between .65 and .75, indicating optimal item cohesion without excessive collinearity or redundancy.

Test-Retest Stability

Because interpersonal trust is conceptualized as a relatively stable cognitive schema that nonetheless remains responsive to diagnostic dyadic interactions, its test-retest reliability reflects balanced temporal stability:

• Over a 4-to-6 week span, test-retest correlations range between r = .78 and .84 in stable dating and married cohorts.
• Over a 12-month longitudinal window, stability coefficients remain solid (r ≈ .60 to .68), with meaningful downward shifts tracking significant relationship transgressions or attachment injuries.

Factor Analysis

The factorial validity of the TRU scale was established through a series of exploratory factor analyses (EFA) and confirmatory factor analyses (CFA) reported in Fletcher et al. (2000).

First-Order Factor Structure

In the development sample (N = 217), EFA with oblimin rotation produced a clean six-factor solution matching the theoretical components of the PRQC framework. The three trust items loaded on a distinct factor with primary loadings > .80 and negligible cross-loadings (< .15) onto other factors (satisfaction, commitment, intimacy, passion, love).

Confirmatory factor analysis confirmed that a correlated six-factor model yielded good fit to the data:

• Model Fit Indices: Comparative Fit Index (CFI) = .95; Non-Normed Fit Index (NNFI/TLI) = .94; Root Mean Square Error of Approximation (RMSEA) = .058 (90% CI [.048, .068]); Standardized Root Mean Square Residual (SRMR) = .045.
• Standardized Factor Loadings for TRU Items:
  • Item 1 (“How much do you trust your partner?”): λ = .88
  • Item 2 (“How much can you count on your partner?”): λ = .86
  • Item 3 (“How dependable is your partner?”): λ = .82

Higher-Order Structural Models

Fletcher et al. (2000) also tested a second-order factor model where a global latent factor of Perceived Relationship Quality (PRQ) accounted for the variance among the six first-order components. In this hierarchical model, the first-order trust factor loaded strongly onto the overarching PRQ dimension (γ ≈ .82), demonstrating that while trust is an integral facet of relationship quality, its measurement model retains strong statistical independence.

Instrument / Measurement Tool

• Formal Tool Name: Trust (General) (TRU) Subscale of the Perceived Relationship Quality Components (PRQC) Inventory
• Authors: Garth J. O. Fletcher, Jeffrey A. Simpson, and Geoff Thomas (2000)
• Instrument Type: Self-report psychometric questionnaire
• Target Population: Adults (aged 18+) currently involved in a romantic relationship (dating, cohabiting, or married)
• Item Count: 3 items
• Administration Time: Less than 1 minute
• Response Scale: 7-point Likert-type scale anchored from 1 = “Not at all” to 7 = “Extremely”
• Scoring Rules:
  • No reverse-scored items.
  • A composite trust index is generated by calculating the mean across all three items (ranging from 1.0 to 7.0) or by calculating a total sum score (ranging from 3 to 21).
  • Higher scores indicate higher levels of perceived trust, dependability, and interpersonal reliance.

Permissions & Fee and Test Year

Publication Year: 2000

Licensing and Accessibility: The Trust (General) (TRU) subscale was published in the Personality and Social Psychology Bulletin by SAGE Publications on behalf of the Society for Personality and Social Psychology (SPSP). As an academic psychometric tool, the items are freely available for non-commercial educational, scientific, and academic research purposes within typical fair-use conventions, provided that appropriate scholarly attribution is cited. Researchers and clinicians do not need to pay royalty fees for academic study deployment. For commercial software applications, clinical trial packaging, or digital proprietary diagnostic systems, formal permissions must be requested via SAGE Publications’ RightsLink licensing service.

References

• Bowlby, J. (1982). Attachment and loss: Vol. 1. Attachment (2nd ed.). Basic Books. (Original work published 1969).
• Fletcher, G. J. O., Simpson, J. A., & Thomas, G. (2000). The measurement of perceived relationship quality components: A confirmatory factor analytic approach. Personality and Social Psychology Bulletin, 26(3), 340–354. https://doi.org/10.1177/0146167200265007
• Gottman, J. M. (1994). What predicts divorce? The relationship between marital processes and marital outcomes. Lawrence Erlbaum Associates.
• Hazan, C., & Shaver, P. (1987). Romantic love conceptualized as an attachment process. Journal of Personality and Social Psychology, 52(3), 511–524. https://doi.org/10.1037/0022-3514.52.3.511
• Kelley, H. H., & Thibaut, J. W. (1978). Interpersonal relations: A theory of interdependence. John Wiley & Sons.
• Larzelere, R. E., & Huston, T. L. (1980). The Dyadic Trust Scale: Toward understanding interpersonal trust in dating relationships. Journal of Marriage and the Family, 42(3), 595–604. https://doi.org/10.2307/351903
• Locke, H. J., & Wallace, K. M. (1959). Short marital-adjustment and prediction tests: Their reliability and validity. Marriage and Family Living, 21(3), 251–255. https://doi.org/10.2307/348022
• Rempel, J. K., Holmes, J. G., & Zanna, M. P. (1985). Trust in close relationships. Journal of Personality and Social Psychology, 49(1), 95–112. https://doi.org/10.1037/0022-3514.49.1.95
• Rusbult, C. E. (1980). Commitment and satisfaction in romantic associations: A test of the investment model. Journal of Experimental Social Psychology, 16(2), 172–186. https://doi.org/10.1016/0022-1031(80)90007-4
• Rusbult, C. E., Martz, J. M., & Agnew, C. R. (1998). The Investment Model Scale: Measuring commitment level, satisfaction level, quality of alternatives, and investment size. Personal Relationships, 5(4), 357–387. https://doi.org/10.1111/j.1475-6811.1998.tb00177.x
• Simpson, J. A. (2007). Psychological foundations of trust. Current Directions in Psychological Science, 16(5), 264–268. https://doi.org/10.1111/j.1467-8721.2007.00517.x
• Spanier, G. B. (1976). Measuring dyadic adjustment: New scales for assessing the quality of marriage and similar dyads. Journal of Marriage and the Family, 38(1), 15–28. https://doi.org/10.2307/350547

Items of the Scale