Source Credibility Scale — Celebrity Endorsers (SCS-CE)

Abstract

The Source Credibility Scale — Celebrity Endorsers (SCS-CE), developed by Roobina Ohanian in 1990, is the preeminent psychometric instrument designed to evaluate consumer perceptions of endorser credibility within marketing, consumer behavior, and advertising psychology. While classical communication paradigms conceptualized source credibility primarily as a two-dimensional construct consisting of expertise and trustworthiness, Ohanian operationalized and validated a comprehensive tripartite framework specifically calibrated for commercial endorsers by incorporating physical attractiveness as an autonomous, co-equal structural dimension. The SCS-CE comprises 15 semantic differential items structured into three orthogonal subscales containing five items each: Attractiveness, Trustworthiness, and Expertise. Each item is scored on a 7-point semantic differential continuum anchored by bipolar adjectives. Across extensive psychometric investigations employing both exploratory and confirmatory factor analyses, the scale has demonstrated exceptional internal consistency (Cronbach’s alpha coefficients systematically exceeding .89 across all dimensions), high convergent and discriminant validity, and robust predictive efficacy regarding consumer attitudes toward advertisements, brand evaluations, and behavioral purchase intentions. The scale remains the global gold standard for academic research and commercial pre-testing of celebrity endorsements, social media influencer evaluations, and public communications.

Keywords

Source Credibility Scale, celebrity endorsers, Roobina Ohanian, advertising psychology, endorser credibility, physical attractiveness, perceived expertise, perceived trustworthiness, semantic differential scale, consumer behavior, brand attitude, purchase intention, source attractiveness model

Authors

The Source Credibility Scale for Celebrity Endorsers was formulated, constructed, and psychometrically validated by Dr. Roobina Ohanian. At the time of the scale’s inception and publication, Dr. Ohanian was affiliated with the Department of Marketing in the College of Business Administration at Georgia State University (Atlanta, Georgia, USA), and later served as a Professor of Marketing at Kennesaw State University. Dr. Ohanian’s scholarly inquiries focus on advertising effectiveness, source credibility dynamics, consumer information processing, and retail strategy. Her seminal 1990 methodological publication in the Journal of Advertising established a rigorous psychometric benchmark that reconciled decades of disparate sociological, rhetorical, and social psychological research into a unified, validated measurement system for marketing practitioners and behavioral scientists.

Purpose

Celebrity endorsement represents one of the most resource-intensive marketing strategies deployed globally, premised on the assumption that the positive characteristics of a recognizable public figure can be transferred to an endorsed brand or product. Prior to Ohanian’s (1990) contribution, empirical investigations into celebrity endorsements relied on ad hoc, unstandardized, or non-validated measurement devices borrowed haphazardly from speech communication and social psychology literatures—such as the scales developed by Hovland, Janis, and Kelley (1953) or Berlo, Lemert, and Mertz (1969). These early instruments were designed to measure political or rhetorical communicators and consistently failed to capture the commercial and aesthetic realities of celebrity advertising.

The primary purpose of the SCS-CE is to provide an empirically validated, theoretically grounded, and psychometrically robust measurement tool specifically tailored to evaluate how consumers process and judge the credibility of commercial spokespersons. The instrument fulfills several crucial clinical, academic, and industrial purposes:

• Diagnostic Pre-Testing in Marketing Campaigns: The scale enables marketing researchers, advertising agencies, and brand strategists to evaluate candidate endorsers across distinct perceptual facets before executing multi-million-dollar endorsement contracts, thereby minimizing financial and reputational exposure.
• Theoretical Hypothesis Testing: In academic consumer psychology, the scale provides standardized dimensional scores necessary to test advanced persuasion theories, including the Elaboration Likelihood Model (ELM), the Meaning Transfer Model, and source congruence/match-up hypotheses.
• Multi-Dimensional Disentanglement: By separating source credibility into three psychometrically distinct factors, the scale allows researchers to observe differential mediating mechanisms. For example, it helps delineate how an endorser’s technical expertise influences utilitarian product evaluations, whereas their physical attractiveness or perceived trustworthiness may independently govern hedonic evaluations and brand trust.
• Cross-Contextual and Digital Evolution: Although conceived for traditional mass media (television and print), the SCS-CE serves as the primary psychometric foundation for contemporary investigations into social media influencers, virtual avatars, and peer endorsers on platforms such as Instagram, YouTube, and TikTok.

Psychological Construct

The SCS-CE operationalizes source credibility as a multi-dimensional psychological construct reflecting the degree to which an information recipient perceives a communicator to possess relevant knowledge, honesty, and appealing personal characteristics that render their persuasive claims acceptable. Rather than conceptualizing credibility as an immutable personal attribute of the celebrity, the construct is situated within social perception theory as a subjective, receiver-based cognitive attribution. Ohanian delineated three core dimensions:

1. Perceived Attractiveness

The Attractiveness dimension captures the endorser’s perceived aesthetic appeal, elegance, personal style, and physical desirability. In classical social psychology, physical attractiveness was frequently relegated to an external peripheral cue rather than a core credibility component. However, in the context of celebrity endorsements, visual appearance operates as a primary communicative currency. Grounded in the halo effect, individuals perceived as physically attractive are frequently attributed socially desirable traits such as sociability, charisma, competence, and success. The SCS-CE operationalizes attractiveness through five bipolar semantic indicators: Attractive—Unattractive, Classy—Not classy, Beautiful—Ugly, Elegant—Plain, and Sexy—Not sexy. This subscale measures not merely superficial facial symmetry, but a broader construct of visual sophistication, aesthetic valence, and aspirational appeal.

2. Perceived Trustworthiness

Trustworthiness reflects the consumer’s confidence in the endorser’s objective intention to communicate honest, sincere, and unbiased assertions regarding the product. Consumers routinely recognize that celebrity spokespersons receive financial compensation, which introduces inherent cognitive skepticism regarding their motives. Perceived trustworthiness serves as a psychological buffer against source derogation; when an endorser is viewed as dependable and principled, consumers attribute the endorsement to genuine personal product conviction rather than solely commercial opportunism. The five semantic indicators constituting this dimension are: Dependable—Undependable, Honest—Dishonest, Reliable—Unreliable, Sincere—Insincere, and Trustworthy—Untrustworthy. This dimension governs consumer risk reduction and psychological safety during persuasive processing.

3. Perceived Expertise

Expertise denotes the extent to which the communicator is perceived as possessing the technical knowledge, specialized training, authoritative experience, or operational skill relevant to the product category or topic under consideration. Within cognitive processing paradigms, source expertise provides authoritative evidence supporting the validity of commercial claims. Notably, expertise is domain-contingent; a professional athlete may possess high perceived expertise when endorsing athletic footwear, yet register low expertise when endorsing enterprise computing software. The five semantic indicators comprising this dimension are: Expert—Not an expert, Experienced—Inexperienced, Knowledgeable—Unknowledgeable, Qualified—Unqualified, and Skilled—Unskilled. Expertise directly influences argument strength processing and central-route cognitive elaboration.

Theoretical Framework

The theoretical architecture of the SCS-CE synthesizes several foundational models from social psychology, communication theory, and consumer behavior:

The Classical Source Credibility Model

The theoretical roots of the construct originate in the pioneering wartime and post-war research conducted by Carl Hovland and his associates at Yale University (Hovland, Janis, & Kelley, 1953; Hovland & Weiss, 1951). The Yale Communication Research Program established that message acceptance is profoundly moderated by source characteristics, isolating two primary components: expertise (the extent to which a speaker is capable of knowing the truth) and trustworthiness (the extent to which a speaker is inclined to tell the truth). According to Hovland’s framework, high-credibility sources facilitate immediate attitude change by reducing cognitive counter-arguing.

The Source Attractiveness and Social Influence Model

Herbert Kelman’s (1958, 1961) classic tripartite model of social influence posited three distinct processes: compliance, identification, and internalization. While credibility (expertise/trustworthiness) primarily operates through internalization (where consumers adopt a stance because it is intrinsically congruent with their value structure), attractiveness operates primarily via identification (where an individual adopts an attitude or behavior to establish or maintain a satisfying self-defining relationship with the source). William McGuire (1968, 1985) expanded this into the Source Attractiveness Model, arguing that persuasive effectiveness depends on familiarity, likeability, and physical similarity or attractiveness. Ohanian reconciled Hovland’s cognitive credibility paradigm with McGuire’s attractiveness framework by establishing that, for celebrity communicators, attractiveness does not operate as an isolated peripheral variable but functions as an integral, structural dimension of credibility itself.

Dual-Process Information Processing Paradigms

The functioning of the SCS-CE is heavily informed by dual-process theories of cognitive persuasion, particularly Petty and Cacioppo’s (1986) Elaboration Likelihood Model (ELM) and Chaiken’s (1980) Heuristic-Systematic Model (HSM). Under low consumer involvement or minimal cognitive processing capacity (peripheral or heuristic route), source characteristics such as celebrity attractiveness or broad likeability serve as simple decision heuristics (“If this attractive/admired celebrity uses this cosmetic, it must be effective”). Conversely, under high involvement or high relevance (central or systematic route), perceived expertise and trustworthiness serve as persuasive arguments or determine the cognitive weighting assigned to detailed product claims.

McCracken’s Meaning Transfer Model

Grant McCracken (1989) critiqued classical source credibility models for treating celebrities merely as bundles of expert or trustworthy attributes, proposing instead the Meaning Transfer Model. McCracken argued that celebrities encode complex cultural meanings, archetypes, lifestyles, and aesthetic values. Ohanian’s inclusion of items such as “Classy” and “Elegant” within the attractiveness subscale bridges psychometrics with meaning transfer theory, capturing qualitative, cultural, and aspirational dimensions beyond simple physical morphology.

Validity

The SCS-CE has undergone exhaustive empirical validation across multiple consumer cohorts, product categories, and cultural environments, establishing exceptional psychometric validity:

Content and Face Validity

During scale construction, Ohanian (1990) conducted an extensive literature search across psychology, communication, sociology, and marketing, generating an initial item pool of dozens of candidate descriptors. A panel of expert judges subjected these items to content evaluation, eliminating ambiguous, redundant, or colloquial terms. Face validity was confirmed via cognitive pre-testing with consumer panels to ensure that the bipolar adjectives intuitively and accurately captured the target constructs without semantic confusion.

Construct and Convergent Validity

Construct validity was formally established through structural equation modeling and confirmatory factor analysis (CFA) across diverse celebrity endorsers representing varying degrees of fame, product alignment, and public perception (including figures such as Linda Evans, Madonna, John Newcombe, and Tom Selleck). Convergent validity is evidenced by high, statistically significant completely standardized factor loadings ($> .70$, with the majority exceeding $.80$ to $.90$, $p < .001$) on their designated theoretical constructs. Furthermore, average variance extracted (AVE) values across subsequent validation studies consistently surpass the recommended $.50$ threshold, demonstrating that the latent constructs account for more variance in their observed indicators than measurement error.

Discriminant Validity

Discriminant validity among the three dimensions was confirmed through competitive model testing. Ohanian evaluated one-factor, two-factor, and three-factor structural specifications; the three-factor model consistently produced a statistically superior fit to the empirical data. Factor intercorrelations, while positive and statistically significant, remained within moderate boundaries (typically ranging between $.30$ and $.60$), confirming that while the dimensions share common variance under the overarching umbrella of source credibility, they remain conceptually and statistically distinct. The square root of the AVE for each dimension exceeds the inter-construct correlation estimates, fulfilling the rigorous Fornell-Larcker criterion.

Predictive and Nomological Validity

Nomological validity has been demonstrated by embedding the scale within broader structural models predicting consumer attitudes and behavioral intentions. In a subsequent predictive validation study, Ohanian (1991) demonstrated that while all three dimensions correlated with consumer responses, perceived expertise was the singular direct and statistically significant determinant of consumers’ purchase intentions for specialized products. Further research (e.g., Amos, Holmes, & Strutton, 2008; Goldsmith, Lafferty, & Newell, 2000) confirmed that the three subscales differentially predict attitude toward the advertisement ($A_{ad}$), attitude toward the brand ($A_b$), and subjective brand credibility, verifying the instrument’s exceptional criterion-related predictive validity.

Reliability

The SCS-CE demonstrates outstanding reliability across independent samples, varying consumer demographics, and distinct media environments. In Ohanian’s (1990) foundational development study, the internal consistency of each subscale was evaluated across multiple endorser-stimuli conditions, yielding the following reliability parameters:

• Attractiveness Subscale: Cronbach’s alpha ($lpha$) coefficients ranged between .89 and .90 across experimental groups.
• Trustworthiness Subscale: Cronbach’s alpha ($lpha$) coefficients ranged between .89 and .92.
• Expertise Subscale: Cronbach’s alpha ($lpha$) coefficients demonstrated the highest consistency, ranging between .94 and .95.

Subsequent psychometric replications have repeatedly substantiated these metrics. Across meta-analytic syntheses and independent validation studies (e.g., Pornpitakpan, 2003, 2004), composite reliability (CR) values regularly surpass $.90$ for each latent dimension. Item-to-total correlations consistently exceed $.70$, well above the conventional psychometric threshold of $.35$ or $.50$. Test-retest reliability assessments conducted across stable time intervals (two- to four-week intervals) exhibit correlation coefficients ($r_{tt}$) exceeding $.80$, indicating strong temporal stability of the instrument when endorser public standing remains constant.

Factor Analysis

The psychometric structure of the SCS-CE was derived and validated through a rigorous two-stage analytical procedure utilizing both Exploratory Factor Analysis (EFA) and Confirmatory Factor Analysis (CFA):

Exploratory Factor Analysis (EFA)

In the scale development phase, an initial pool of semantic differential items was administered to an exploratory sample ($N = 250$). Principal Component Analysis (PCA) accompanied by orthogonal (Varimax) and oblique (Promax) rotations was conducted. Latent root criteria (eigenvalues $> 1.0$) and scree plot inspections decisively revealed a three-factor solution accounting for over 70% of the total variance. Items loaded cleanly onto their intended theoretical dimensions with strong primary factor loadings ($> .75$) and negligible cross-loadings ($< .30$), enabling the retention of exactly five pristine indicators per latent construct.

Confirmatory Factor Analysis (CFA)

To confirm factorial invariance and model stability, the refined 15-item scale was tested on an independent validation sample ($N = 516$) using structural equation modeling software (LISREL VI/VII). The hypothesized three-factor measurement model exhibited exceptional goodness-of-fit across multiple product-endorser scenarios:

• Goodness of Fit Index (GFI): Exceeded $.90$ to $.95$ across test conditions.
• Adjusted Goodness of Fit Index (AGFI): Consistently exceeded $.88$ to $.92$.
• Root Mean Square Residual (RMSR): Ranged between $.030$ and $.050$, indicating minimal residual covariance.
• Comparative Fit Indices: Later re-examinations using modern fit metrics report Comparative Fit Index (CFI) and Tucker-Lewis Index (TLI) values exceeding $.95$, alongside Root Mean Square Error of Approximation (RMSEA) values below $.06$ (90% CI [.045, .068]).

Parameter estimates indicated that all 15 observed variables loaded robustly onto their specified latent factors ($t$-values all statistically significant at $p < .001$), confirming the invariant, tripartite factor structure of perceived celebrity source credibility.

Instrument / Measurement Tool

• Construct Measured: Multi-dimensional perceived source credibility of celebrity endorsers (comprising Attractiveness, Trustworthiness, and Expertise).
• Format: 15-item semantic differential rating scale anchored by opposite bipolar adjectives.
• Administration Time: Approximately 3 to 5 minutes.
• Target Population: Adult consumers, general public, market research panels, and academic experimental cohorts.
• Response Scale: 7-point semantic differential scale (scored 1 to 7, where 7 indicates maximum endorsement of the positive credibility attribute, or reversed depending on presentation order).
• Subscale Structure:
  • Attractiveness: Items 1 through 5 (measuring visual, aesthetic, and stylistic appeal).
  • Trustworthiness: Items 6 through 10 (measuring perceived integrity, honesty, and dependability).
  • Expertise: Items 11 through 15 (measuring technical qualification, knowledge, and operational skill).
• Scoring and Interpretation Procedures:
  • Subscale Mean Scores: Calculate the arithmetic mean of the five items within each dimension (sum of item scores divided by 5). This yields a continuous score ranging from 1.00 to 7.00 for Attractiveness, Trustworthiness, and Expertise independently.
  • Subscale Sum Scores: Alternatively, calculate the sum of the five items for each dimension, yielding dimensional composite scores ranging from 5 to 35.
  • Dimensional Profiling: Ohanian strongly advises against combining all 15 items into a single aggregate omnibus credibility score, as the three dimensions operate via distinct psychological mechanisms. Instead, researchers should evaluate endorsers via a multi-dimensional profile (e.g., High Attractiveness / High Trustworthiness / Low Expertise).

Permissions & Fee and Test Year

The Source Credibility Scale — Celebrity Endorsers was originally published in 1990 by Dr. Roobina Ohanian in the Journal of Advertising (Volume 19, Issue 3, pages 39–52), published by the American Academy of Advertising (now distributed by Taylor & Francis). The instrument is widely considered to be in the public domain for non-commercial academic research and scholarly educational purposes, provided that appropriate formal attribution is granted to the original author and journal. Commercial organizations, market research firms, and corporate entities intending to incorporate the scale into proprietary commercial testing software or commercial ad evaluation systems should verify licensing requirements with the copyright holder or publisher (Taylor & Francis / American Academy of Advertising). No separate per-administration testing fee is mandated for academic usage.

References

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McGuire, W. J. (1968). Personality and attitude change: An information-processing approach. In A. G. Greenwald, T. C. Brock, & T. M. Ostrom (Eds.), Psychological foundations of attitudes (pp. 171–196). Academic Press. https://doi.org/10.1016/B978-1-4832-3071-9.50013-1

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Ohanian, R. (1990). Construction and validation of a scale to measure celebrity endorsers’ perceived expertise, trustworthiness, and attractiveness. Journal of Advertising, 19(3), 39–52. https://doi.org/10.1080/00913367.1990.10673191

Ohanian, R. (1991). The impact of celebrity spokespersons’ perceived image on consumers’ intention to purchase. Journal of Advertising Research, 31(1), 46–54.

Petty, R. E., & Cacioppo, J. T. (1986). The Elaboration Likelihood Model of persuasion. Advances in Experimental Social Psychology, 19, 123–205. https://doi.org/10.1016/S0065-2601(08)60214-2

Pornpitakpan, C. (2003). Validation of the celebrity endorsers’ credibility scale: Evidence from Asians. Journal of Marketing Management, 19(1-2), 179–195. https://doi.org/10.1080/0267257X.2003.9728206

Pornpitakpan, C. (2004). The persuasiveness of source credibility: A critical review of five decades’ evidence. Journal of Applied Social Psychology, 34(2), 243–281. https://doi.org/10.1111/j.1559-1816.2004.tb02547.x

Items of the Scale