Further Validation of the Consumer Susceptibility to Interpersonal Influence Scale

William O. Bearden, University of South Carolina
Richard G. Netemeyer, Louisiana State University
Jesse E. Teel, University of South Carolina
ABSTRACT - Recently, a two-factor (normative and informational), 12-item measure of consumer susceptibility to interpersonal influence (SUSCEP) has been developed (Bearden, Netemeyer, and Teel 1989). The present paper summarizes a series of additional analyses designed to further examine the dimensionality and validity of this scale. These efforts include first, the results of correlating the SUSCEP measures with a number of consumer specific and general personality traits. Second, previously-reported tests of the SUSCEP scale employing measures of attention-to-social-comparison-information and self-esteem are expanded to include comparison tests with interpersonal influence measures similar to those used by Park and Lessig (1977). The results of these efforts provide additional support for the validity of the two dimensional-SUSCEP scale.
[ to cite ]:
William O. Bearden, Richard G. Netemeyer, and Jesse E. Teel (1990) ,"Further Validation of the Consumer Susceptibility to Interpersonal Influence Scale", in NA - Advances in Consumer Research Volume 17, eds. Marvin E. Goldberg, Gerald Gorn, and Richard W. Pollay, Provo, UT : Association for Consumer Research, Pages: 770-776.

Advances in Consumer Research Volume 17, 1990      Pages 770-776

FURTHER VALIDATION OF THE CONSUMER SUSCEPTIBILITY TO INTERPERSONAL INFLUENCE SCALE

William O. Bearden, University of South Carolina

Richard G. Netemeyer, Louisiana State University

Jesse E. Teel, University of South Carolina

ABSTRACT -

Recently, a two-factor (normative and informational), 12-item measure of consumer susceptibility to interpersonal influence (SUSCEP) has been developed (Bearden, Netemeyer, and Teel 1989). The present paper summarizes a series of additional analyses designed to further examine the dimensionality and validity of this scale. These efforts include first, the results of correlating the SUSCEP measures with a number of consumer specific and general personality traits. Second, previously-reported tests of the SUSCEP scale employing measures of attention-to-social-comparison-information and self-esteem are expanded to include comparison tests with interpersonal influence measures similar to those used by Park and Lessig (1977). The results of these efforts provide additional support for the validity of the two dimensional-SUSCEP scale.

INTRODUCTION

Interpersonal influence is viewed as an important factor in consumer decision-making (e.g., Ajzen and Fishbein 1980; Gatignon and Robertson 1985; Kiel and Layton 1981; Stafford and Cocanougher 1977). Only recently, though, have efforts been made to strengthen measurement in this area of consumer research. The objective of this paper is to present the results of additional validation research for the recently developed consumer susceptibility to interpersonal influence scale (SUSCEP) (Bearden et. al. 1989). First, a brief review pertaining to the interpersonal influence literature and the SUSCEP scale is offered. Second, the hypotheses, methods and results of research relating the SUSCEP scale to a number of personality characteristics are presented. Next, the hypotheses, methods and results of a follow-up effort which compares the SUSCEP measures to alternative self-report measures of interpersonal influence (cf. Park and Lessig 1977) are presented. [With a few exceptions, the results summarized in this paper represent additional validation tests not presented in the original manuscript describing the initial construction and validation of the SUSCEP scale. These exceptions include: the confirmatory factor analysis and reliability tests of the original scale briefly used to introduce the follow-up correlational validity tests; the correlations between ATSCI and the informational and normative dimensions for the student sample; and the two correlations between the SUSCEP factors and the behavioral indices reported as comparison to the Park and Lessig results.] Lastly, a brief discussion and suggestions for future research in interpersonal influence are offered.

Consumer Susceptibility to Interpersonal Influence

Consumer susceptibility to interpersonal influence is assumed to be a general trait that exists to varying degrees in different individuals. This construct is derived from McGuire's (1968) concept of influenceability and is consistent with early research demonstrating that individuals differ in their response to social influence (Allen 1965, Asch 1958; Cox and Bauer 1964; Janis 1954; Kelman 1961). Interpersonal influence has been conceptualized as being either informational or normative where informational influence is defined as the tendency to accept information from others as evidence about reality (Deutsch and Gerard 1955). Based on the work of Kelman (1961), normative influence has been viewed as either value expressive or utilitarian (Bearden and Etzel 1982; Burnkrant and Cousineau 1975; Park and Lessig 1977; Price, Feick, and Higie 1987). Value expressiveness reflects the individual's desire to enhance his or her self-image and is characterized by the need for association in terms of being similar to a reference group and feeling for another referent. Utilitarian influence is reflected in attempts to comply with the expectations of others in order to gain rewards or to avoid punishments mediated by others (Burnkrant and Cousineau (1975, p. 207).

Several consumer behavior studies support the existence of the three manifestations of interpersonal influence (i.e., informational, value expressive and utilitarian) (e.g., Bearden and Etzel 1982; Ford and Ellis 1980; Park and Lessig 1977; Pincus and Waters 1977; Price, Feick, and Higie 1987; Stafford 1966; Witt and Bruce 1972). Based on these manifestations, the consumer susceptibility to interpersonal influence scale (SUSCEP) was developed. However, the scale development procedures revealed that the value expressive and utilitarian factors were not distinct and hence, they were combined into one normative factor (Bearden, et. al. 1989). SUSCEP currently consists of 12 items--eight comprising a normative interpersonal influence factor and four comprising an informational influence factor. Though a number of validation procedures were performed, additional research is warranted to further establish SUSCEP's validity.

CORRELATIONS WITH RELATED CONSTRUCTS

Hypotheses

A number of measures assessing both consumer specific constructs and general personality traits were used to further evaluate the validity of the SUSCEP scale. First, two consumer-specific variables are hypothesized to be related to susceptibility to interpersonal influence, i.e., consumer confidence and consumer interpersonal orientation. Consumer confidence is defined as the individual's perceived ability to choose the best buy from available brands; consumer interpersonal orientation is defined as the willingness to interact with others regarding consumer related topics. These two variables represent likely antecedents of individual susceptibility to interpersonal influence. It is predicted that general consumer interpersonal orientation will be positively related to measures of susceptibility to interpersonal influence. In contrast, it is felt that confidence and susceptibility to interpersonal influence will be inversely related. These predictions are consistent with earlier findings that individuals high in consumer confidence should perceive less need for information from others and demonstrate less concern for the opinions of others (Locander and Hermann 1979). Formally stated, the first two hypotheses read:

H1: Both dimensions of SUSCEP (i.e., the normative and informational dimensions) will be positively correlated with consumer Interpersonal Orientation.

H2: Both dimensions of SUSCEP will be negatively correlated with consumer confidence.

A number of constructs in social psychology assess interpersonal relations among individuals. Three of these constructs, i.e., attention-to-social-comparison-information (Lennox and Wolfe 1984), inner-other directedness (Kassarjian 1962), and self-monitoring (Lennox and Wolfe 1984) are included here for further validation tests of the SUSCEP scale. Strong positive correlations are predicted for attention-to-social-comparison-information (ATSCI). ATSCI addresses the general tendency to conform and has been found related to the concern for reactions of others (Lennox and Wolfe 1984). Consequently, the measure should be strongly correlated with the normative factor and, although less so, positively correlated with the informational factor. Thus. the following hypothesis is offered:

H3: Both dimensions of SUSCEP will have a positive correlation with ATSCI. However, the normative factor of the SUSCEP scale will be more highly correlated with ATSCI than will the informational factor.

Inner-other directedness and self-monitoring represent generalized traits that deal with the individual's interest in and responsiveness to others. For example, the frames of reference for other directed individuals are the values and attitudes of others around them (Kassarjian 1962). Similarly, effective social integration and adjusting to what is situationally appropriate are the hall marks of the high self-monitor (Lennox and Wolfe 1984). These measures reflect operationalizations of generalized constructs that have some overlap with consumer susceptibility to interpersonal influence and, hence, modest positive correlations are predicted:

H4: Both dimensions of SUSCEP will exhibit modest positive correlations with measures of inner-other directedness and self-monitoring.

Method

Subjects and Measures. Two samples were utilized in the correlational tests. In the first, 220 adult consumers responded to the 12-item SUSCEP scale along with measures of consumer confidence and consumer orientation. The developmental procedures for the confidence and orientation measures began with an initial pool of 39 items. Similar judgmental procedures to those employed in the scale development literature (cf. Bearden, et. al. 1989) resulted in deletion of 15 of these items. Examination of corrected item-to-total correlations and an initial confirmatory factor analysis for the confidence and interpersonal orientation items resulted in deleting 5 confidence and 9 consumer IO statements. The remaining items were then examined in a subsequent two- construct confirmatory factor analysis. Although the chi2 value was significant (chi2 = 87.97, df = 37), all items loaded as hypothesized and each t-value exceeded 7.27. In sum, these analyses resulted in 5 remaining items for the measures of consumer confidence (e.g., "As a rule, I have a great deal of confidence in my ability to evaluate products and brands.") and consumer IO (e.g., "I enjoy discussing products and brands with friends.") Internal consistency reliability estimates (coefficient alpha) were .81 and .79 for consumer confidence and interpersonal orientation, respectively.

In the second sample, 141 undergraduate students responded to the SUSCEP scale along with the three general personality measures. The scales developed by Lennox and Wolfe (19843 were used to measure attention-to-social-comparison-information and self-monitoring. Inner-other directedness was assessed via Kassarjian's (1962) scale. The top portion of Table 1 presents the summary statistics and reliability estimates for these measures.

Results

The factor structure and internal consistency of the SUSCEP scale was examined first (Bearden, et. al. 1989). (Only a brief summary of the factor structure tests is reported here.) [The SUSCEP statements, the item-to-total correlations and factor loadings are presented in the original manuscript (Bearden, et. al. 1989, p. 477). Due to space limitations, they have not been reported in this paper.] For the adult sample, the hypothesized 2-factor structure (8 normative and 4 informational items) yielded a chi2 = 79.83 (df = 53) with a correlation between factors of phi = .37. In comparison, the null model had a chi2 = 845.58 (df = 66) while the unidimensional model had a chi2 = 167.84 (df = 54). Thus, the two factor structure had a significantly better fit to the data than either the null or unidimensional model. The variance extracted estimates for the normative and informational factors were .53 and .55 and the square of the phi correlation between factors (.14) wac less than the variance extracted estimates for both factors. Thus, evidence for the convergent validity-among items and discriminant validity between factors was provided (cf. Fornell and Larcker 1981). In addition, internal consistency reliability estimates for the normative and informational scales were .87 and .83. In the student sample, the two factor model had a chi2 = 107.41 (df = 53) with phi = .44. The competing one-factor structure had a chi2 = 255.60 (df = 54) and the null model yielded a chi2 = 820.10 (df = 66). The differences in fit, again, were significant. The variance extracted estimates for the normative factor and informational factors were .54 and .50 and were greater than the square of the correlation between them (phi2 = .19). The internal consistency estimates were .88 and .82 for the normative and informational factors, respectively. In sum, the dimensionality and reliability of the SUSCEP scale were largely supported.

TABLE 1

SUMMARY STATISTICS AND RELIABILITY ESTIMATES FOR MEASURES AND CORRELATIONAL RESULTS

The correlations between consumer self-confidence and consumer IO and the two dimensions of SUSCEP are shown in the bottom portion of Table 1. Confidence was inversely related to the two sub-dimensions and consumer IO was positively related to the sub-dimensions, as hypothesized. It is interesting to note that consumer IO was most strongly correlated (.50, p < .01) with the informational dimension, i.e., the factor most closely reflecting verbal communications with others. Similarly, consumer confidence was most strongly correlated (-.53, p < .01) with the normative factor, i.e., the dimension reflective of the expectations of others. In sum, H1 and H2 were supported.

Table 1 also presents correlational findings from the student sample. As predicted, ATSCI did correlate positively with the two sub-dimensions of the SUSCEP scale and was more strongly correlated with the normative factor than with the informational factor (t = 6.02, p < .01, for a test between dependent correlations (Cohen and Cohen 1975)) offering support for H3. Although not overwhelming, the correlations pertaining to H4 generally adhere to the anticipated pattern.

COMPARISON WITH PARK AND LESSIG ITEMS

One of the purposes of developing the SUSCEP scale was to provide consumer researchers with a general measure of consumer susceptibility to interpersonal influence (Bearden, et. al. 1989). Though other measures of consumer susceptibility to interpersonal influence exist, they are primarily product/situation specific (cf. Brinberg and Plimpton 1986; Park and Lessig 1977). Thus, it was predicted that SUSCEP should have stronger correlations with personality traits and other generalized indices of interpersonal influence than product/situation specific measures. To examine this premise, the SUSCEP scale was compared with the Park and Lessig (1977) measures of interpersonal influence in two separate studies. The first study examined the relationships between SUSCEP, the items of Park and Lessig and the ATSCI (Lennox and Wolfe 1984) and self-esteem (Eagly 1967) measures. The second study investigated the relationships between the Park and Lessig (1977) measures of susceptibility to interpersonal influence along with the SUSCEP scale and a series of aggregate indices of behaviors performed over multiple time periods (cf. Epstein 1979, 1980; Lastovicka and Joachimsthaler 1988). The following hypotheses are offered:

H5: The SUSCEP measures will exhibit stronger correlations with ATSCI and self-esteem than will the Park and Lessig measures.

H6: The SUSCEP measures will exhibit stronger correlations with an aggregate indices of consumer behaviors than will the Park and Lessig measures.

Method

In the original research of Park and Lessig (1977), 20 products were evaluated for each of their 14 items. For comparison purposes, five of these same 20 products were randomly selected for this study. Similar to their original procedures, the relevance of each item for each product was evaluated on a four-place scale ranging from "not relevant" (1) to "highly relevant" (4). Responses to their informational and normative items were averaged over products and then summed to form informational and normative interpersonal influence scales. The average internal consistency estimates were 0.55 and 0.86, respectively.

Park and Lessig (1977) computed scores for each product by assigning the highest score obtained on any one of the items representing a given dimension of susceptibility to interpersonal influence to that product. These high scores were then averaged across products to produce one score for each component of interpersonal influence. To enhance the comparisons between SUSCEP and the Park and Lessig measures, we summed their items and used this composite in a series of comparison tests. Since this approach differed from Park and Lessig's original scoring procedures, additional comparison tests were conducted using their original scoring procedures. The results of these analyses were similar to those found using the summed comparison measures.

ATSCI and Self-Esteem. A convenience sample of 47 undergraduate business students responded to a questionnaire containing the 14 Park and Lessig items for five products, the ATSCI scale, the twenty-item self-esteem scale described by Eagly (1967), and the SUSCEP scale. The internal consistency estimates for the ATSCI and the self esteem measures were 0.82 and 0.88. Again, ATSCI was expected to be more strongly correlated with the normative factor than with the informational factor. However, it was predicted that the correlations between ATSCI and the Park and Lessig items should be lower than the ATSCI-SUSCEP correlations. It was also predicted that both dimensions of the SUSCEP scale would be inversely related to self esteem (McGuire 1968).

Relationships With Behavioral Indices. Similar to the procedures of Epstein (1979, 1980), the alternative measures of susceptibility to interpersonal influence (i.e., the Park and Lessig measures and the SUSCEP scale) were correlated in a second study with an aggregate index of consumer behaviors. First, a convenience sample of 35 undergraduate business students was used to elicit 21 and 17 behaviors reflecting the definitions of the normative and informational dimensions of susceptibility to interpersonal influence. Example normative behaviors included worrying about what others thought of the respondent's selection of clothing to wear and copying the purchase behavior of someone the respondent admired. Example informational behaviors included discussing products with friends or relatives and/or seeking expert advice of others prior to making a purchase.

TABLE 2

COMPARISON WITH PARK AND LESSIG ITEMS AND CORRELATIONS WITH OTHER CONSTRUCTS

Following elicitation of these behaviors, a questionnaire containing the Park and Lessig items for 5 products along with the SUSCEP items was administered to a new sample of 43 subjects. Next, at four separate intervals, these same 43 subjects reported their performance regarding the 21 normative and 17 informational behaviors during the preceding 48 hour period. Similar to the methods used by Epstein (1979), the behavioral measures were averaged over administrations to form behavioral indices.

Results

The reliability and dimensionality of the SUSCEP scale were examined first. The results again show support for validity of the scale. For the sample examining the relationships between the two measures of susceptibility to interpersonal influence and ATSCI and self-esteem, the hypothesized two-factor structure for SUSCEP was again supported (chi2 = 97.96, df = 53). The differences between the two-factor structure and a null model (chi2 = 348.28, df = 66) and a one-factor model (chi2 = 119.38, df = 54) were significant. The variance extracted estimates were .41 and .55 for the informational and normative factors while the correlation among the two factors was .36 (phi2 = .13). In addition, the internal consistency reliability estimates were .72 and .91 for the informational and normative factors. Overall, these results are supportive of the dimensionality and internal consistency of the scale.

For the sample examining the relations between the behavioral indices, the hypothesized two-factor SUSCEP scale (chi2 = 133.99, df = 53) again had a better fit to the data than did the null model (chi2 = 355.27, 1 If = 66) or a unidimensional model (chi2 = 138.91, I If = 54). The internal consistency estimates were .91 and .72 for the informational and normative factors.

Table 2 presents the correlational results for the comparisons between SUSCEP and the Park and Lessig measures. As reported in the original scale development, ATSCI was again more strongly correlated (for a test of differences between correlations) with the normative dimension of SUSCEP than with the informational dimension (t 4.37, p < .01). Importantly, the normative factor of SUSCEP was more highly correlated with the ATSCI scale than was the Park and Lessig measure of normative influence (t = 3.43, p c .01). Furthermore, the correlation between the informational dimension of SUSCEP and self-esteem was greater than the correlation between the Park and Lessig informational measure and self-esteem (t = 1.67, p < .05). Though the correlation between the normative dimension of SUSCEP and self-esteem was stronger than the correlation between the normative measure of Park and Lessig and self-esteem, this difference was not statistically significant.

The correlation between the even and odd summary averages for the normative and informational behavioral indices were 0.72 and 0.80. As Table 2 indicates, neither correlation between the normative and informational behavioral indices and the Park and Lessig measures was significant. In contrast, the normative factor of the SUSCEP scale was significantly correlated with the normative behavioral index (r = .37, p c .05) and, although the magnitude of this correlation is modest, it compares favorably with the trait-behavior correlations reported by Epstein (1979, p. 1118). In addition, the correlation between the normative factor of SUSCEP and the normative behavioral index was significantly greater than the correlation between the normative factor of the Park and Lessig measure and the normative behavioral index (t = 1.89, p < .05). Although the correlation between the SUSCEP informational factor and the informational behavioral index was stronger than the correlation between the Park and Lessig informational measure and the behavioral informational index, the difference was not statistically significant. Overall then, H5 and H6 were largely supported.

DISCUSSION

This research sought to provide additional evidence regarding the validity of the recently developed consumer susceptibility to interpersonal influence scale (Bearden, et. al. 1989). The first series of tests examined the relationships between the two dimensions of the SUSCEP scale and a number of consumer specific and psychological traits. Overall, the results supported the convergent and discriminant validity of SUSCEP. Subsequently, SUSCEP was compared to previously used measures of interpersonal influence (i.e., Park and Lessig 1977). The general pattern of correlations demonstrated that the SUSCEP scale was more strongly related to behavioral indices reflecting both normative and informational influence than the Park and Lessig measures. Again, since the Park and Lessig items were product specific and the SUSCEP items more applicable to a wider range of consumer behaviors, the higher correlations between SUSCEP and the behavioral indices were expected.

The SUSCEP scale should prove to be useful for a number of consumer behavior applications. First, studies examining the differences in susceptibility to interpersonal influences based on gender and age could be performed. Earlier research posited that females have a stronger interpersonal orientation toward others than males (e.g., Solomon 1963). It has also been suggested that females interact more frequently with their peers about consumption matters and are more susceptible to social influence (i.e., possess stronger social motivations for consumption) than males (Churchill and Moschis 1979). Overall, age might exhibit a curvilinear relationship with the highest levels of susceptibility to interpersonal influence occurring during the teen and early adult years. However, for informational influence alone, research indicates that the influence of others (largely the extended family) as sources of information increases with advancing age (cf. Phillips and Sternthal 1977). Lastly, the SUSCEP scale should be useful in experimental research. Studies that examine normative vs. informational influence in terms of referent similarity and expertise could be undertaken (Burnkrant and Cousineau 1975; Price, Feick, and Higie 1987). Also, experiments could be designed where subjects are exposed to either informational or normative influence, and then the extent of the influence observed and measured. This observed level of susceptibility could then be compared with self-report levels via the SUSCEP scale, offering a stronger validation test for SUSCEP.

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