Consumer Susceptibility to Interpersonal Influence (CSII)

Abstract

The Consumer Susceptibility to Interpersonal Influence (CSII) scale, developed by William O. Bearden, Richard G. Netemeyer, and Jesse E. Teel in 1989, is an empirically validated psychometric instrument designed to measure individual differences in consumers’ tendencies to conform to reference group norms and assimilate social information during purchase decisions. Rooted in social psychology and classical consumer behavior literature, the CSII conceptualizes interpersonal influence as a general trait comprising two distinct dimensions: normative influence and informational influence. Normative influence encompasses both value-expressive needs (the desire to enhance self-image through psychological association with a reference group) and utilitarian compliance (the willingness to conform to group expectations to gain rewards or avoid sanctions). Informational influence captures an individual’s tendency to accept product evaluations and behavioral observations from credible others as evidence of reality.

The CSII consists of 12 self-report items evaluated on a 7-point Likert scale ranging from 1 (“strongly disagree”) to 7 (“strongly agree”). Developed from an initial pool of 166 candidate items and refined through successive stages of exploratory and confirmatory factor analyses, the instrument exhibits strong psychometric properties. Internal consistency reliability estimates across multiple validation samples typically range from Cronbach’s alpha values of .82 to .89 for the overall scale, with subscale reliabilities consistently exceeding recommended academic benchmarks (.75 to .90). Confirmatory factor analyses demonstrate that the two-factor oblique model provides superior fit relative to unidimensional formulations. The CSII has demonstrated robust convergent, discriminant, and predictive validity across diverse market environments, consumer demographics, and international cultural contexts, establishing itself as a foundational metric in advertising research, brand management, and social influence research.

Keywords

consumer susceptibility to interpersonal influence, CSII, normative influence, informational influence, reference groups, consumer conformity, social influence, consumer psychometrics, brand choice, social proof

Authors

The Consumer Susceptibility to Interpersonal Influence scale was formulated, validated, and published by a distinguished team of academic researchers in marketing and consumer psychology:

• William O. Bearden, Ph.D. — Professor Emeritus of Marketing at the Darla Moore School of Business, University of South Carolina. Dr. Bearden has published extensively on consumer behavior, scale development, and psychometric measurement methodologies in top-tier marketing journals, serving on multiple editorial review boards including the Journal of Consumer Research.
• Richard G. Netemeyer, Ph.D. — Ralph A. Beeton Professor of Free Enterprise at the McIntire School of Commerce, University of Virginia. Dr. Netemeyer is widely recognized for his methodological expertise in structural equation modeling, psychometric measurement validation, and consumer psychology.
• Jesse E. Teel, Ph.D. — Professor Emeritus of Marketing at the Darla Moore School of Business, University of South Carolina. His scholarship spans consumer response modeling, retailing strategies, and behavioral decision-making.

Purpose

The primary purpose of the CSII is to provide an empirically rigorous, generalizable instrument to capture interpersonal social influence tendencies in marketplace transactions. While social psychologists and market researchers have long acknowledged that consumer preferences do not develop in a social vacuum, early empirical efforts were hindered by the absence of a standardized, psychometrically sound measurement tool tailored specifically to consumer contexts. Traditional measures often relied on ad hoc operationalizations or adapted general social conformity scales that failed to address the nuances of brand selection, conspicuous consumption, and market navigation.

The CSII addresses this gap by formalizing consumer susceptibility to interpersonal influence as a continuous individual difference variable (trait). In consumer research, the scale allows investigators to explain why specific consumer segments respond vigorously to peer endorsements, influencer marketing, and social proof, whereas others rely primarily on personal utility assessments or technical specifications. It serves as an essential explanatory variable in structural equation models examining brand loyalty, luxury consumption, adoption of innovations, ethical consumerism, and viral marketing dynamics.

In strategic brand management and commercial market research, understanding a target segment’s CSII profile enables practitioners to design effective marketing communications. For consumer segments scoring high on normative susceptibility, promotional messaging emphasizing social approval, peer prestige, and group belonging is maximally effective. Conversely, for segments displaying elevated informational susceptibility, marketing communications must prioritize expert evaluations, transparent performance metrics, product demonstration trials, and verifiable customer reviews. Furthermore, the scale plays a critical role in public policy and health communication campaigns, assisting researchers in determining how anti-smoking, sober driving, and pro-environmental behaviors can be accelerated through peer norms.

Psychological Construct

The psychological construct assessed by the CSII is defined as the need to identify with or enhance one’s image in the opinion of significant others through the acquisition and use of products and brands, the willingness to conform to the expectations of others regarding purchase decisions, and the tendency to learn about products and services by observing others or seeking information from them (Bearden et al., 1989). The construct is bifurcated into two primary operational dimensions:

1. Normative Influence

Normative influence reflects an individual’s inclination to conform to the positive expectations of another person or group. Within classical social psychology, this dimension incorporates two distinct conceptual facets: utilitarian influence and value-expressive influence. In consumer contexts, however, empirical data demonstrate that these two sub-dimensions load onto a single higher-order normative factor.

• Utilitarian Influence: Occurs when an individual complies with group expectations in order to achieve rewards or avoid punishments administered by the group. In a purchase setting, this manifests as buying the brands that friends, colleagues, or family members expect, specifically to prevent social friction, disapproval, or alienation. For example, a young professional may purchase business-formal attire compliant with an office dress code to avoid subtle social censure.
• Value-Expressive Influence: Operates through an individual’s psychological drive to enhance their self-concept through identification with a reference group. The consumer internalizes group values or adopts the consumption patterns of admired reference groups to project a desired social identity. For instance, an individual might purchase a high-end electric vehicle or athletic apparel brand not out of functional necessity, but because owning that brand symbolizes membership in an environmentally conscious or health-oriented peer group.

2. Informational Influence

Informational influence refers to the tendency to accept information obtained from others as credible evidence about reality. Consumers characterized by elevated informational susceptibility actively search for guidance from knowledgeable acquaintances, family members, or independent experts, particularly under conditions of high perceived risk, ambiguous product evaluations, or limited personal expertise.

Informational influence operates through two behavioral mechanisms: actively seeking direct verbal advice from peers and family, and passively observing the consumption choices of others to infer brand quality. For example, a consumer looking to purchase complex computer hardware or personal financial services may seek recommendations from knowledgeable colleagues or observe which equipment industry veterans choose, interpreting those choices as signals of superior reliability.

Theoretical Framework

The CSII is grounded in foundational social psychological theories of conformity, interpersonal communication, and reference group behavior developed during the mid-twentieth century. Its primary theoretical scaffold is derived from the pioneering work of Morton Deutsch and Harold B. Gerard (1955), who distinguished between normative and informational social influences in psychological experimentation.

Deutsch and Gerard challenged Solomon Asch’s classical conformity paradigms by positing that conformity is not a monolithic behavioral phenomenon. They defined normative social influence as an influence to conform with the positive expectations of another, whereas informational social influence was defined as an influence to accept information obtained from another as evidence about reality. In consumer environments, this dichotomy was expanded by C. Whan Park and V. Parker Lessig (1977), who operationalized Deutsch and Gerard’s framework into reference group influence paradigms across three distinct behavioral motivations: informational, utilitarian, and value-expressive.

The CSII also interfaces directly with Herbert Kelman’s (1958, 1961) classic tripartite model of opinion change:

• Compliance: An individual adopts a behavior not because of private belief, but to achieve a favorable reaction or avoid punishment from another person or group (aligning with utilitarian normative influence).
• Identification: An individual adopts behavior derived from another person or group because this behavior is associated with the satisfying, self-defining relationship to that group (aligning with value-expressive normative influence).
• Internalization: An individual adopts behavior because the content of the induced behavior is intrinsically rewarding and congruent with the person’s existing value system, often stimulated by credible expert testimony (aligning with informational influence).

Bearden, Netemeyer, and Teel synthesized these theoretical models, demonstrating that while Kelman and Park & Lessig separated utilitarian and value-expressive mechanisms on theoretical grounds, consumers rarely separate these internal drives in naturalistic market settings. Consequently, the CSII model models utilitarian and value-expressive dynamics under a consolidated normative construct, positioned alongside informational influence as complementary pillars of consumer susceptibility.

Validity

The construct validity of the CSII has been confirmed through rigorous multi-stage psychometric evaluations involving varied empirical samples, including undergraduate student cohorts, non-student adult consumers, and national survey respondents:

Convergent and Discriminant Validity

During scale validation, Bearden et al. (1989) examined correlations between the CSII dimensions and related psychological constructs. The CSII displayed substantial positive correlations with variables conceptually tied to interpersonal sensitivity and conformity:

• Self-Monitoring: The normative subscale correlates positively with Lennox and Wolfe’s (1984) Revised Self-Monitoring Scale, particularly the “Sensitivity to Expressive Behavior of Others” dimension ($r \approx .35$ to $.45$), demonstrating that high-normative consumers are acutely attuned to external social cues.
• Attention to Social Comparison Information (ATSCI): Normative CSII scores correlate strongly with ATSCI ($r > .50$), confirming that the construct captures an individual’s vigilance regarding what peers wear, use, and approve.
• Self-Esteem: Correlates negatively with the normative subscale ($r \approx -.20$ to $-.30$), supporting the theoretical expectation that individuals with lower self-esteem rely more heavily on external social approval to validate consumer selections.
• Social Desirability: Discriminant validity was supported by demonstrating weak, statistically non-significant correlations ($r < .15$) with Marlowe-Crowne Social Desirability scores, confirming that CSII items do not simply reflect a response bias toward social approval.

Predictive and Nomological Validity

Predictive validity was substantiated by examining actual brand selection tasks across public versus private consumption goods. High-normative individuals demonstrated significantly greater brand conformity when purchasing publicly consumed goods (such as athletic shoes, automobiles, and wristwatches) compared to privately consumed goods (such as mattresses or household cleaners). Furthermore, the informational subscale effectively predicts information search behavior, including the number of peer consultations, online review reading duration, and reliance on word-of-mouth (WOM) communications before high-involvement purchases.

Reliability

The CSII exhibits stable internal consistency and temporal reliability across numerous empirical studies and cultural settings:

• Internal Consistency (Cronbach’s Alpha): In the original validation studies by Bearden, Netemeyer, and Teel (1989), internal consistency estimates were consistently high across developmental and cross-validation samples. The overall 12-item scale achieved Cronbach’s alpha coefficients ranging from $.88$ to $.89$. For the subscales, the normative subscale achieved alpha coefficients ranging between $.85$ and $.88$, while the informational subscale demonstrated alpha values between $.78$ and $.83$. Subsequent studies (e.g., Netemeyer et al., 1992; Kropp et al., 2005) have supported these figures, reporting composite reliabilities regularly above $.80$.
• Test-Retest Reliability: Temporal stability was evaluated across a four-week test-retest interval. The test-retest correlation coefficients were $.79$ for the normative subscale, $.75$ for the informational subscale, and $.81$ for the composite instrument, demonstrating that the CSII measures a relatively stable behavioral trait rather than a transient emotional state.
• Average Variance Extracted (AVE): Confirmatory factor evaluations demonstrate that the AVE for both dimensions regularly exceeds the recommended threshold of $.50$, establishing that the variance captured by the latent construct is greater than the variance attributable to measurement error.

Factor Analysis

The factor structure of the CSII was established through exploratory factor analysis (EFA) and validated via confirmatory factor analysis (CFA) utilizing maximum likelihood estimation:

Initial Extraction and Dimensionality

Starting with a 166-item initial pool, iterative rounds of content analysis, item-to-total correlations, and exploratory principal axis factoring with oblique rotations were executed. Although early theoretical paradigms proposed three factors (informational, utilitarian, and value-expressive), exploratory scree tests and eigenvalues consistently revealed a two-factor structure. The utilitarian and value-expressive items collapsed cleanly into a unified factor (normative influence), while the informational items formed a distinct second factor.

Confirmatory Factor Analytic Results

CFA conducted on independent adult samples confirmed that the two-factor correlated (oblique) model fit the data substantially better than a single-factor unidimensional model. Standardized factor loadings across validation studies consistently exceed $.60$, with most items loading between $.65$ and $.85$ on their designated latent factors. Cross-loadings between normative and informational dimensions are minimal and non-significant.

Goodness-of-fit metrics from Bearden et al. (1989) and subsequent structural replications illustrate strong model fit:

• Comparative Fit Index (CFI): $ge .93$ to $.96$
• Tucker-Lewis Index (TLI / NNFI): $ge .92$ to $.95$
• Root Mean Square Error of Approximation (RMSEA): $le .055$ to $.068$
• Standardized Root Mean Square Residual (SRMR): $le .050$

The correlation between the two latent factors is typically moderate ($r \approx .35$ to $.55$), indicating that while normative and informational influences share common ground as social influence mechanisms, they remain distinct constructs.

Instrument / Measurement Tool

• Test Type: Psychometric self-report survey scale / Individual difference measure
• Construct Measured: Consumer susceptibility to interpersonal social influence in commercial decision-making
• Number of Items: 12 items
• Factor Structure: Two correlated dimensions
  • Normative Influence: 8 items assessing conformity, peer approval, social belonging, and image enhancement
  • Informational Influence: 4 items assessing reliance on peer consultation, expert advice, and behavioral observation
• Response Format: 7-point Likert scale (1 = strongly disagree to 7 = strongly agree)
• Administration Time: Approximately 3 to 5 minutes
• Scoring Rules:
  • No items are reverse scored.
  • Subscale scores can be computed as a sum or mean across assigned items.
  • A global CSII index can be calculated by averaging or summing all 12 items when an overall measure of social susceptibility is required.

Permissions & Fee and Test Year

The Consumer Susceptibility to Interpersonal Influence scale was published in 1989 in the Journal of Consumer Research (Volume 15, Issue 4). Under academic fair-use guidelines, the scale is widely accessible and free of charge for non-commercial academic research, university teaching, and scholarly scientific investigations.

Researchers wishing to utilize the instrument in proprietary, non-academic corporate consulting or commercial market testing should consult the copyright policies of Oxford University Press (the current publisher of the Journal of Consumer Research) or request explicit permission from the original lead author, Dr. William O. Bearden. When using the scale in published literature, appropriate scholarly attribution following APA formatting guidelines is required.

References

• Bearden, W. O., Netemeyer, R. G., & Teel, J. E. (1989). Measurement of consumer susceptibility to interpersonal influence. Journal of Consumer Research, 15(4), 473–481. https://doi.org/10.1086/209186
• Deutsch, M., & Gerard, H. B. (1955). A study of normative and informational social influences upon individual judgment. The Journal of Abnormal and Social Psychology, 51(3), 629–636. https://doi.org/10.1037/h0046408
• Kelman, H. C. (1958). Compliance, identification, and internalization: Three processes of attitude change. Journal of Conflict Resolution, 2(1), 51–60. https://doi.org/10.1177/002200275800200106
• Kelman, H. C. (1961). Processes of opinion change. Public Opinion Quarterly, 25(1), 57–78. https://doi.org/10.1086/266996
• Kropp, F., Lavack, A. M., & Silver, Z. S. (2005). Values and conformity: A cross-cultural investigation. International Marketing Review, 22(1), 7–28. https://doi.org/10.1108/02651330510581154
• Lennox, R. D., & Wolfe, R. N. (1984). Revision of the Self-Monitoring Scale. Journal of Personality and Social Psychology, 46(6), 1349–1364. https://doi.org/10.1037/0022-3514.46.6.1349
• Netemeyer, R. G., Bearden, W. O., & Teel, J. E. (1992). Consumer susceptibility to interpersonal influence and need for uniqueness: A comparison of two scales. Advances in Consumer Research, 19(1), 404–407.
• Park, C. W., & Lessig, V. P. (1977). Students and housewives: Differences in susceptibility to reference group influence. Journal of Consumer Research, 4(2), 102–110. https://doi.org/10.1086/208685

Items of the Scale