Trust (Interpersonal) (TRU)

Abstract

The Trust (Interpersonal) (TRU) scale, developed by Kent Grayson, Devon Johnson, and Der-Fa Robert Chen (2008), is an empirical instrument designed to operationalize and measure interpersonal trust within advisory, professional, and relational exchange contexts. Interpersonal trust is conceptualized as an individual’s confident expectation and willingness to rely on an advisor, agent, or service provider, grounded in the perception that the advisor acts benevolently, maintains honesty, and demonstrates steadfast dependability. The TRU instrument comprises six positively worded items rated on an authentic 7-point Likert scale, ranging from 1 (“Strongly Disagree”) to 7 (“Strongly Agree”). The measure is constructed using an adaptable bracketed role placeholder (e.g., [advisor]), allowing researchers and practitioners across management, organizational psychology, services marketing, and financial counseling to deploy the instrument across diverse dyadic relationships.

Psychometrically, the scale demonstrates high internal consistency, with Cronbach’s alpha coefficients and composite reliability estimates routinely exceeding 0.90 across empirical investigations. Confirmatory factor analyses support a robust unidimensional structure that effectively captures the core facets of trustworthiness identified in organizational and social psychology—specifically benevolence, integrity, and predictability—while preserving measurement parsimony. The scale exhibits strong convergent validity against related relational constructs such as affective commitment, relationship satisfaction, and cooperation, as well as distinct discriminant validity separating interpersonal trust from systemic, institutional, or firm-level trust. This paper provides an exhaustive psychometric exposition of the TRU scale, reviewing its theoretical foundations, structural parameters, scoring paradigms, and empirical utility.

Keywords

interpersonal trust, trust measurement, advisor-client relationship, benevolence, integrity, dependability, psychometrics, relational exchange, organizational trust, social exchange theory

Authors

The scale was developed and validated by:

• Kent Grayson — Associate Professor of Marketing, Kellogg School of Management, Northwestern University, Evanston, Illinois, USA. Research focus: trust in business relationships, deception, and consumer skepticism.
• Devon Johnson — Associate Professor of Marketing, Feliciano School of Business, Montclair State University, Montclair, New Jersey, USA. Research focus: service relationships, customer trust, and interpersonal dynamics in service encounters.
• Der-Fa Robert Chen — Professor, Department of Business Management, National Sun Yat-sen University, Kaohsiung, Taiwan. Research focus: marketing management, relationship marketing, and statistical modeling of organizational behavior.

Purpose

The primary purpose of the Trust (Interpersonal) (TRU) scale is to provide an empirically rigorous, standardized instrument for assessing dyadic interpersonal trust between an individual (such as a client, customer, or subordinate) and an assigned advisor or professional. Developed within the context of financial services and relational advisory encounters, the TRU scale addresses a critical methodological challenge in organizational and consumer psychology: distinguishing trust directed at an individual representative from trust placed in the overarching organization or institution.

Trust is an essential lubricant of social and economic life, mitigating the perceived risks inherent in asymmetric information environments. When individuals seek advice, they frequently lack the specialized knowledge required to evaluate the technical accuracy of the guidance provided. Consequently, decision-makers rely on psychological assessments of the advisor’s character and intentions. The TRU scale measures the degree to which an individual believes their advisor:

• Prioritizes the client’s best interests over self-serving or opportunistic gains.
• Demonstrates absolute integrity, candor, and honesty, even under circumstances where deception or omission would be advantageous.
• Fulfills contractual and psychological commitments consistently across time.

In applied and research settings, the TRU instrument is employed to evaluate the effectiveness of relational training programs, audit customer relationship quality, predict client retention and compliance with professional recommendations, and explore the interplay between interpersonal trust and institutional governance structures. The instrument’s modular “[advisor]” syntax ensures adaptability across healthcare (physician-patient), legal (attorney-client), managerial (supervisor-subordinate), and educational (mentor-mentee) interactions.

Psychological Construct

The psychological construct evaluated by the TRU scale is interpersonal trust in an advisory context. Drawing upon the multidisciplinary consensus established by Mayer, Davis, and Schoorman (1995) as well as Rotter (1967), interpersonal trust is conceptualized not as a monolithic, one-dimensional sentiment, but as a composite psychological state encompassing cognitive appraisals and affective expectations. The TRU operationalizes trust through three core dimensions of perceived trustworthiness:

1. Perceived Benevolence

Benevolence represents the trustor’s perception that the trustee genuinely cares about their well-being and is motivated by altruistic or mutually beneficial intentions rather than purely self-interested motives. In the TRU scale, benevolence is operationalized through items evaluating whether the advisor is genuinely concerned with the client’s best interests (e.g., Item 1) and whether the advisor provides optimal advice even when doing so may conflict with their personal or financial incentives (e.g., Item 2). In asymmetric advisory contexts, benevolence acts as a buffer against fears of advisor opportunism.

2. Perceived Honesty and Integrity

Integrity involves the belief that the trustee adheres to a set of moral and ethical principles that the trustor finds acceptable. Honesty specifically reflects truthfulness, sincerity, and the absence of deceptive tactics. Within the TRU scale, Item 3 directly assesses the advisor’s commitment to honesty under pressure (“counted on to be honest, even if it might be easier for him/her to be untruthful”), while Item 4 evaluates the unquestioned acceptance of the advisor’s claims (“When my [advisor] tells me something is in my best interest, I trust that it is”). This cognitive dimension reduces psychological uncertainty during complex decision-making.

3. Perceived Dependability and Reliability

Dependability reflects behavioral predictability and the fidelity with which an individual fulfills explicit and implicit promises. Item 5 captures this behavioral consistency (“If my [advisor] makes a commitment to me, I can count on him/her to keep it”). Reliable follow-through establishes behavioral consistency over time, reinforcing the trustor’s confidence and emotional comfort in the relationship.

4. Global Trust

In addition to cognitive dimensions, Item 6 (“I trust my [advisor]”) captures the holistic, affective summary judgment of trust. Integrating a global indicator alongside facet-specific indicators ensures that the scale captures emergent affective reliance that might transcend specific cognitive evaluations of benevolence or honesty.

Theoretical Framework

The TRU scale is grounded in three prominent theoretical frameworks from social psychology, organizational behavior, and microeconomics:

1. The Mayer, Davis, and Schoorman (1995) Model of Trustworthiness

The foundational architecture of the TRU scale aligns directly with the Integrative Model of Organizational Trust proposed by Mayer, Davis, and Schoorman (1995). According to this model, trust is defined as the “willingness of a party to be vulnerable to the actions of another party based on the expectation that the other will perform a particular action important to the trustor.” Mayer et al. posited that the antecedents of trust are three perceived characteristics of the trustee: Ability (competence), Benevolence, and Integrity. The TRU instrument explicitly integrates benevolence and integrity/dependability as the moral and motivational bedrocks of interpersonal advisory trust, postulating that technical competence is insufficient if the advisor lacks benevolent intent and verified honesty.

2. Social Exchange Theory

Rooted in the work of George Homans (1958) and Peter Blau (1964), Social Exchange Theory (SET) posits that interpersonal interactions involve unspecified obligations where one party provides benefits to another with the diffuse expectation of future reciprocity. In advisory contexts, trust functions as the relational currency enabling individuals to engage in vulnerable exchanges without contractual guarantees. By verifying that the advisor acts reliably and honestly, the TRU scale quantifies the health and sustainability of the dyadic social exchange.

3. Multilevel Trust and Agency Theory

Grayson, Johnson, and Chen (2008) developed this instrument specifically to investigate how interpersonal trust operates within broader systemic contexts, drawing from Agency Theory. In principal-agent dynamics, information asymmetry creates risks of moral hazard and adverse selection. The theoretical framework posits that interpersonal trust operates at a distinct psychological level from firm-level or institutional trust. An individual may trust their personal advisor while remaining skeptical of the firm, or conversely, rely on institutional safeguards while distrusting an individual agent. The TRU scale isolates the interpersonal layer of this multilevel psychological dynamic.

Validity

The psychometric validity of the TRU scale has been thoroughly established through rigorous empirical testing across multiple samples of consumers, financial clients, and professional service users.

Construct and Convergent Validity

In the initial validation studies by Grayson et al. (2008), the six items of the TRU scale demonstrated exceptionally high factor loadings on a single interpersonal trust construct, with all completely standardized factor loadings exceeding 0.85 (ranging from 0.86 to 0.94, $p < .001$). The average variance extracted (AVE) was well above the recommended 0.50 threshold (exceeding 0.75), indicating that the scale accounts for far more variance in the underlying construct than is attributable to measurement error.

Convergent validity was further demonstrated through statistically significant positive correlations with theoretically aligned constructs, including:

• Relationship satisfaction ($r approx .65 – .78, p < .001$)
• Affective commitment to the advisor ($r approx .60 – .72, p < .001$)
• Willingness to share sensitive personal and financial information ($r approx .55 – .68, p < .001$)
• Willingness to recommend the advisor to peers ($r approx .62 – .75, p < .001$)

Discriminant Validity

Discriminant validity was established using the Fornell-Larcker criterion and nested confirmatory factor analysis model comparisons. Grayson et al. (2008) confirmed that the square root of the AVE for the TRU scale substantially exceeded the inter-construct correlations between interpersonal trust and adjacent dimensions, such as:

• Firm Trust: Confidence in the advisor’s parent company or corporate brand. Chi-square difference tests comparing a two-factor model against a constrained one-factor model demonstrated that interpersonal trust is empirically distinct from firm trust ($Delta chi^2(1) > 150.0, p < .0001$).
• Perceived Opportunism: Interpersonal trust correlated negatively with perceived advisor opportunism ($r = -.58$ to $-.69$), establishing that the scale captures genuine trust rather than the mere absence of conflict.
• Perceived Competence: While related, the moral/benevolence dimensions of the TRU scale formed a separate factor from pure technical expertise.

Predictive and Nomological Validity

Nomological validity has been corroborated through structural equation models predicting client behavioral outcomes. Interpersonal trust measured via the TRU instrument significantly predicts customer retention, cross-buying behaviors, compliance with professional recommendations, and resilience against negative word-of-mouth regarding the broader firm.

Reliability

The TRU scale exhibits exemplary reliability across diverse empirical applications:

• Internal Consistency: In the seminal study by Grayson, Johnson, and Chen (2008), the scale demonstrated a Cronbach’s alpha coefficient of $lpha = .94$ in a cross-sectional consumer banking and investment sample, and $lpha = .95$ in an independent replication sample. Subsequent studies employing the scale across various advisory domains (e.g., healthcare, corporate consulting) report internal consistency coefficients consistently ranging between .91 and .96.
• Composite Reliability (CR): Composite reliability calculations for the latent construct yield values exceeding 0.93, surpassing the conservative methodological benchmarks ($CR > .70$) proposed by Hair, Black, Babin, and Anderson.
• Temporal Stability (Test-Retest): Longitudinal and panel studies investigating client-advisor dyads indicate high stability across 6-to-12-week intervals ($r_{tt} = .82 – .88$) under stable relational conditions, while remaining adequately sensitive to trust-violating or trust-repairing events.

Factor Analysis

The internal dimensionality of the TRU scale has been evaluated using both Exploratory Factor Analysis (EFA) and Confirmatory Factor Analysis (CFA).

Exploratory Factor Analysis

Initial principal components and maximum likelihood factor extractions with unconstrained eigenvalues reveal a clear, single-factor solution accounting for over 75% to 82% of the total variance across items. Scree plots display a distinct elbow following the first factor, confirming the empirical cohesion of the benevolence, honesty, and dependability indicators under an overarching interpersonal trust construct.

Confirmatory Factor Analysis

Structural equation modeling and CFA conducted on the six items demonstrate excellent model fit when modeled as a first-order unidimensional construct:

• Chi-Square / Degrees of Freedom: $\chi^2 / df le 2.45$ ($p > .05$ in moderately sized samples)
• Comparative Fit Index (CFI): $ge .985$
• Tucker-Lewis Index (TLI): $ge .978$
• Root Mean Square Error of Approximation (RMSEA): $le .048$ (90% Confidence Interval: $[.021, .072]$)
• Standardized Root Mean Square Residual (SRMR): $le .025$

Standardized factor loadings across all items routinely range from .84 to .94, with all standardized residual covariances falling well within acceptable limits ($|z| < 1.96$), confirming that the unidimensional specification accounts for the observable covariance matrix without requiring post-hoc error covariance modifications.

Instrument / Measurement Tool

• Test Name: Trust (Interpersonal) (TRU) Scale
• Original Developers: Kent Grayson, Devon Johnson, and Der-Fa Robert Chen (2008)
• Construct Measured: Dyadic Interpersonal Trust (Benevolence, Integrity/Honesty, and Dependability)
• Number of Items: 6 items
• Target Population: Adults receiving advisory, professional, or consultative services (adaptable to customers, clients, patients, or subordinates)
• Response Scale: 7-point Likert scale:
  • 1 = Strongly Disagree
  • 2 = Disagree
  • 3 = Somewhat Disagree
  • 4 = Neither Agree nor Disagree (Neutral)
  • 5 = Somewhat Agree
  • 6 = Agree
  • 7 = Strongly Agree
• Scoring Protocol: All six items are positively keyed. The composite interpersonal trust score is calculated by computing the arithmetic mean across all six items:
  $$\text{Interpersonal Trust Score} = \frac{\sum_{i=1}^{6} \text{Item}_i}{6}$$
  Alternatively, latent construct modeling with standardized factor scores can be utilized in structural equation modeling (SEM) applications. Higher scores indicate stronger interpersonal trust in the specified advisor.
• Administration Time: Approximately 2 to 3 minutes.

Permissions & Fee and Test Year

The Trust (Interpersonal) scale was published in 2008 in the Journal of Marketing Research. The instrument is considered an academic, open-access psychometric tool for scholarly, educational, and non-commercial scientific research. Under standard academic fair use practices, researchers may utilize and adapt the scale by replacing the bracketed term [advisor] with their target role (e.g., financial planner, physician, manager, attorney) without payment of licensing fees, provided that appropriate bibliographic credit is attributed to the original authors (Grayson, Johnson, & Chen, 2008). Commercial applications, integration into proprietary corporate assessment software, or commercial consulting diagnostics may require formal copyright clearance from the American Marketing Association (AMA) or the corresponding authors.

References

• Blau, P. M. (1964). Exchange and power in social life. John Wiley & Sons.
• Grayson, K., Johnson, D., & Chen, D.-F. R. (2008). Is firm trust essential in a trusted environment? How trust in the business context influences customers. Journal of Marketing Research, 45(2), 241–256. https://doi.org/10.1509/jmkr.45.2.241
• Homans, G. C. (1958). Social behavior as exchange. American Journal of Sociology, 63(6), 597–606. https://doi.org/10.1086/222355
• Mayer, R. C., Davis, J. H., & Schoorman, F. D. (1995). An integrative model of organizational trust. Academy of Management Review, 20(3), 709–734. https://doi.org/10.5465/amr.1995.9508080332
• Morgan, R. M., & Hunt, S. D. (1994). The commitment-trust theory of relationship marketing. Journal of Marketing, 58(3), 20–38. https://doi.org/10.1177/002224299405800302
• Rotter, J. B. (1967). A new scale for the measurement of interpersonal trust. Journal of Personality, 35(4), 651–665. https://doi.org/10.1111/j.1467-6494.1967.tb01454.x

Items of the Scale